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PREVEX® FLAMMABILITY ANALYZER
MODEL 670 SERIES
INSTRUCTION MANUAL
Control Instruments® Corporation
25 Law Drive, Fairfield, New Jersey 07004, USA
www.controlinstruments.com
Telephone: (973) 575-9114
Fax (973) 575-0013
WARNING!
THIS ANALYZER IS USED FOR THE SAFE OPERATION OF MACHINERY AND
PROCESSES, AND TO PREVENT FIRES AND EXPLOSIONS.
YOU MUST READ AND UNDERSTAND THE ENTIRE INSTRUCTION MANUAL
BEFORE INSTALLATION, OPERATION, CALIBRATION, OR SERVICING OF THIS
ANALYZER.
OBSERVE, UNDERSTAND, AND OBEY ALL WARNINGS IN THIS MANUAL.
FAILURE TO PROPERLY INSTALL, OPERATE, CALIBRATE OR SERVICE THIS
ANALYZER MAY RESULT IN A FIRE OR EXPLOSION THAT CAN CAUSE
DESTRUCTION OF PROPERTY OR SERIOUS BODILY INJURY.
PREVEX® Flammability Analyzer
Model 670 series FTA Instruction Manual
For All Model Numbers
SNR671, SNR672, SNR674 and SNR675
Software Version 5.12 and above
Publication number: H7FTA118 rev Q
Published by:
Control Instruments Corporation
25 Law Drive
Fairfield, New Jersey, 07004 USA
Printed and bound in the United States of America
Copyright ©1999-2006 Control Instruments Corporation. All rights reserved. No part of the contents of this book may
be reproduced or transmitted in any form or by any means without the express written permission of the publisher.
Control Instruments®, PrevEx®, Sentron®, Varigraph®, DataMax®, SmartMax®, ViewPort® and the Control
Instruments logo are U.S. registered trademarks of Control Instruments Corporation. PrevEx is a registered trademark
in Europe. Kalrez is a registered trademark of E I Dupont. All trademarks are the property of their respective owners.
The PrevEx analyzer has patents pending in the USA and Europe.
The contents of this manual are subject to change without notice. While precautions have been taken in the preparation
of this manual, the publisher assumes no responsibility for errors or omissions. Control Instruments Corporation
assumes no liability for damages resulting from the use of information contained in this manual.
Revision History:
First publication: July 1999
Rev Q: February 2014
WARRANTY INFORMATION
If within one year from the date of shipment, the equipment purchased from Control
Instruments Corporation, or any part of that equipment, fails because of a manufacturing
defect, Control Instruments Corporation will supply a replacement part F.O.B. Fairfield,
New Jersey. The furnishing of a replacement part under the terms of this warranty will
apply to the original warranty period, and will not serve to extend the warranty period
beyond the original one year. This warranty does not cover the cost of labor involved in
diagnostic calls or in servicing or replacing parts.
This warranty shall not apply if the equipment has been subjected to misuse, negligence,
accident in transit or has been hampered or altered in any way, or if the equipment
components have been subjected to forces or stresses beyond those recommended or
specified by the manufacturer.
THE FOREGOING CONSTITUTES OUR SOLE WARRANTY WITH RESPECT
TO THE EQUIPMENT COVERED HEREBY, AND ALL OTHER WARRANTIES
EXPRESS
OR
IMPLIED,
INCLUDING
WARRANTIES
OF
MERCHANTABILITY AS WELL AS WARRANTIES OF FITNESS FOR A
PARTICULAR PURPOSE ARE HEREBY EXCLUDED. IN NO EVENT SHALL
CONTROL INSTRUMENTS CORPORATION BE LIABLE FOR SPECIAL OR
CONSEQUENTIAL DAMAGES.
TABLE OF CONTENTS
1.
Introduction .................................................................................................................................... 1
1.1.
Warnings ......................................................................................................................... 1
1.2.
Qualified Personnel ........................................................................................................ 1
1.3.
Software Versions............................................................................................................ 2
1.4.
Special Notices ................................................................................................................ 2
1.5.
Models ............................................................................................................................. 5
2.
Theory of Operation ....................................................................................................................... 7
2.1.
Hazards of Flammable Gases and Vapors ...................................................................... 7
2.2.
Measuring Principle........................................................................................................ 8
2.3.
Flame Cell and Sensing Flame ....................................................................................... 9
2.4.
Flow Diagram ............................................................................................................... 10
2.5.
Electrical Diagram........................................................................................................ 11
2.6.
The Controller ............................................................................................................... 12
2.7.
Air Dilution Option ....................................................................................................... 17
2.8.
Fail-safe Considerations ............................................................................................... 19
3.
4.
Specifications ................................................................................................................................. 22
Installation ..................................................................................................................................... 26
4.1.
Unpacking ..................................................................................................................... 26
4.2.
Equipment, materials, and utilities................................................................................ 26
4.3.
Location and Mounting ................................................................................................. 27
4.4.
Sample and Exhaust Tubing .......................................................................................... 27
4.5.
Utilities .......................................................................................................................... 32
4.6.
Compressed air supply .................................................................................................. 32
4.7.
Fuel supply cylinders .................................................................................................... 34
4.8.
Zero and Span Test Gases ............................................................................................. 35
4.9.
AC Power ...................................................................................................................... 35
4.10. RS-485 Serial Communications .................................................................................... 36
4.11. Relays and Outputs ....................................................................................................... 37
4.12. Wiring for EMC (Electromagnetic Compatibility) ........................................................ 38
4.13. Remote Control Inputs .................................................................................................. 39
4.14. Visual and Audible Alarms and Indicators ................................................................... 40
4.15. Security.......................................................................................................................... 40
5.
Display, Indicators, Controls ....................................................................................................... 41
5.1.
Indicators ...................................................................................................................... 41
5.2.
Menu and Select Pushbuttons ....................................................................................... 41
5.3.
Navigation: Menus and Registers ................................................................................. 42
5.4.
COMMANDS ................................................................................................................ 43
5.5.
GAUGES ....................................................................................................................... 44
5.6.
CAL MENU ................................................................................................................... 44
5.7.
ALARMS ........................................................................................................................ 45
5.8.
OUTPUTS ..................................................................................................................... 46
5.9.
COM PORT ................................................................................................................... 47
5.10. Flashlight-activated Commands ................................................................................... 47
6.
Startup Procedure ........................................................................................................................ 48
6.1.
Initial conditions ........................................................................................................... 48
6.2.
Air ................................................................................................................................. 48
6.3.
Fuel ............................................................................................................................... 48
6.4.
Power ............................................................................................................................ 48
6.5.
Ignition .......................................................................................................................... 49
6.6.
Preliminary Calibration ................................................................................................ 49
6.7.
Inputs and outputs ......................................................................................................... 50
6.8.
Records.......................................................................................................................... 50
Stability test ................................................................................................................... 50
6.9.
TABLE OF CONTENTS
7.
Calibration .................................................................................................................................... 51
7.1.
Initial calibration .......................................................................................................... 51
7.2.
Recalibration Procedure ............................................................................................... 58
8.
Operation....................................................................................................................................... 59
8.1.
Reading and status. ....................................................................................................... 59
8.2.
Acknowledge Command. ............................................................................................... 59
8.3.
Reset Command ............................................................................................................. 60
9.
Maintenance .................................................................................................................................. 61
9.1.
General information and precautions ........................................................................... 61
9.2.
Analyzer Maintenance Record ...................................................................................... 63
9.3.
“Service Needed” Messages ......................................................................................... 64
9.4.
Scheduled Maintenance................................................................................................. 67
9.5.
Readings ........................................................................................................................ 67
9.6.
Utilities .......................................................................................................................... 67
9.7.
Gauges .......................................................................................................................... 68
9.8.
Recalibration ................................................................................................................. 68
9.9.
Leak test ........................................................................................................................ 68
9.10. Alarm test ...................................................................................................................... 68
9.11. Semi-annual review ....................................................................................................... 68
9.12. Flow System Preventative Maintenance........................................................................ 70
9.13. Cleaning ........................................................................................................................ 71
9.14. Fuel Regulator Adjustment............................................................................................ 74
10.
Troubleshooting ............................................................................................................................ 75
10.1. AC Power ...................................................................................................................... 75
10.2. Flame Cell Temperature ............................................................................................... 75
10.3. Air Inlet Pressure .......................................................................................................... 75
10.4. Fuel Inlet Pressure ........................................................................................................ 75
10.5. Spark ............................................................................................................................. 76
10.6. Flame ............................................................................................................................ 76
10.7. Sample Flow .................................................................................................................. 76
10.8. Calibration Flow ........................................................................................................... 77
10.9. Troubleshooting by status message ............................................................................... 77
10.10. DATA LOST and COLD START ............................................................................................ 79
10.11. Drift ............................................................................................................................... 80
11.
Spare Parts .................................................................................................................................... 82
11.1. Parts for Preventative Maintenance.............................................................................. 82
11.2. Parts for Routine Maintenance ..................................................................................... 82
11.3. Parts for Maintenance and Repair ................................................................................ 82
11.4. Parts for Repair............................................................................................................. 82
11.5. Spare Part Photos ......................................................................................................... 83
12.
Serial Communications ................................................................................................................ 87
12.1. Serial Communications Specifications .......................................................................... 87
12.2. Serial Communications Notes ....................................................................................... 87
12.3. Register Conversion Factors ......................................................................................... 88
12.4. Registers ........................................................................................................................ 89
INTRODUCTION
1.
Introduction
Read and understand this instruction manual before installation, operation or maintenance of the
analyzer.
IMPORTANT: In this manual, the marking WARNING! indicates important
instructions. Failure to understand and follow these instructions can result in a fire or
explosion, destruction of property or serious bodily injury.
1.1.
Warnings
Observe the following warning notices and all additional warnings found within this manual:
WARNING! Read
and understand this instruction manual before installation, operation or servicing.
WARNING! This
analyzer measures the flammability of gases. It does not provide protection from
toxic gases, or from the toxic effects of flammable gases. Many flammable gases have toxic effects.
Some can pose an immediate danger to life at concentrations too low for this analyzer to measure.
WARNING! The analyzer contains electric circuits. Proper handling procedures for high voltage
circuits must be observed. Keep all covers tight when circuits are energized. Do not remove covers
unless circuits are de-energized, or the atmosphere is known to be well below the lower flammable
or explosive limit.
WARNING! The analyzer is purged. In hazardous areas, maintain the proper purge rate and
pressurization as required by code. If purge or pressurization is lost, restore it immediately or
disconnect electrical power. Purge for a minimum of 10 minutes at 24 liters per minute flow before
turning on electrical power.
WARNING! Do not operate unless the flame arrestors are installed. Operation without flame arrestors
may allow flame propagation that could ignite the process or atmosphere being measured.
WARNING! The analyzer uses hydrogen or propane fuel. Observe proper handling precautions. Turn
the fuel supply off whenever the air supply to the analyzer is off.
WARNING! During calibration the analyzer cannot make readings or activate alarms. Perform
calibration only when it will not interfere with safety of the process being monitored. During
calibration, the analyzer signals cannot be used for control or safety function.
WARNING! Do not bypass, disable, or tamper with this analyzer. Secure it from unauthorized access.
WARNING! Fuel pressure failure, low oxygen conditions or flammable concentrations above the
measurement range, can cause reading errors. Off-scale readings in either direction may indicate a
hazardous gas concentration.
1.2.
Qualified Personnel
Installation, operation and maintenance must be performed by qualified personnel only. This requires
understanding of: instrumentation, handling compressed gases, flammable fuels, electric circuits, the
behavior of the gases and vapors in the process being monitored, and the relevant codes, standards
and recommended practices for flammable gas detectors and the process being monitored.
WARNING! All personnel who install, operate, or maintain this device must read, and understand this
instruction manual. Short-form instructions and guides are not an acceptable substitute.
All personnel who monitor, use, or depend upon this device, must understand the hazards associated
with flammable gases and vapors, the meaning of the readings made by this analyzer, and the
meaning of all alarms and indicators.
PrevEx®InstructionManual
1
INTRODUCTION
Use this manual in conjunction with the codes and standards that apply to the hazards of the
flammable gases and vapors, and the intended use of the analyzer as a means of protection.
Specifications and requirements vary in different locations. The device must be reviewed for the
particular requirements of the local authority having jurisdiction1.
WARNING! The user must review and ensure compliance with all applicable safety codes.
1.3.
Software Versions
This manual covers software versions 5.12 and above. The software version installed in the analyzer
can be found in the VERSION register on the ALARMS menu.
1.4.
Special Notices
1.4.1.
Special Notice for Factory Mutual Research (FMR) approval:
FMR Approval of the 4-20mA output from the SNR670 Series sensor/controller does not include or
imply approval of the apparatus connected to the instrument. In order to maintain FMR Approval of
the system, all 4-20mA or current loop instruments connected must also be FMR Approved.
FMR Approval allows the presence and operation of serial communications software in the SNR670
Series sensor/controller (Modbus protocol). However, the communications functions provided are
not included in the FMR Approval.
In order to maintain FMR approval for Division 2 area it is important to occasionally inspect the
alarm relays within the electronics assembly for package integrity.
WARNING!
1.4.2.
In order to maintain FMR approval, the DANGER alarm must latch, either by the LATCHES
register, or through the use of an equivalent external latching relay or device.
Special notice for FMc approval.
ATTENTION: POUR DES RAISONS DE SECURITE, CET EQUIPEMENT DOIT ETRE UTILISE, ENTRETENU ET
REPARE UNIQUEMENT PAR UN PERSONNEL QUALIFIE. ETUDIEZ LE MANUEL D‘INSTRUCTIONS EN
ENTIER AVANT D‘UTILISER, ‗ENTRETENIR OU DE REPARER L‘EQUIPEMENT.
For instructions in French or other languages, please contact the manufacturer or its representative.
1.4.3.
Special notice for ATEX approval - using the analyzer for the safe functioning of
equipment
The PrevEx analyzer with software version 5.20 has been tested and approved by DEKRA EXAM
(PFG No. 41300302) according to the following standards:
EN 61779-1:2000 "Electrical apparatus for the detection and measurement of flammable gases Part 1: General requirements and test methods"
EN 61779-4:2001-07 "Electrical apparatus for the detection and measurement of flammable
gases - Part 4: Performance requirements for group II apparatus indicating a volume fraction up
to 100 % lower explosive limit"
1
In the USA, refer to the American National Standards Institute ANSI/ISA RP12.13 ―Recommended Practice
for the Installation, Operation and Maintenance of Combustible Gas Detectors.‖ Under ATEX and
CENELEC guidelines see EN 50073 ―Guide for the selection, installation, use and maintenance of apparatus
for the detection and measurement of combustible gases and oxygen.‖
2
Control Instruments Corp.
INTRODUCTION
EN 50271:2002-05 "Electrical apparatus for the detection and measurement of combustible
gases, toxic gases or oxygen - Requirements and tests for apparatus using software and/or digital
technologies"
To comply with the general requirements of EN 61779-1 the DANGER alarm of the analyzer must
always be configured as latching.
1.4.4.
Special notice for ATEX approval - installation in a non-hazardous zone
Models which are ATEX marked may be installed in a non-hazardous zone while the sample and
exhaust are connected with a Ex Zone 1 without the requirements of section 1.4.5, if instrument air
(dry, clean compressed air free of flammables) is supplied to the analyzer with an inlet pressure of 20
psig (1.4 bar) at the inlet ―F‖, supplying a constant stream of air through the instrument, and if the
purge outlet is equipped with the supplied venting outlet using a sintered metal filter to maintain
ingress protection. If necessary during installation, move the cap from ―F‖ to inlet ―C,‖ move nut and
ferrules from ―C‖ to ―F,‖ and attach vent fitting to position ―K‖ as indicated on the Purge Diagrams
in section 1.5.2.
1.4.5.
Special notices for ATEX approval - installation in Ex Zone 1
Model designations SNR671-T6, SNR672-T4, SNR672-T3, SNR674-T3 or SNR674-T2 and
SNR675-T2 can be installed and operated in, or connected to, Ex Zone 1 or Ex Zone 2 hazardous
locations, explosion group II C. The EC-type examination has been performed by DMT - Deutsche
Montan Technologie GmbH. The EC-type examination certificate is DMT03 ATEX G 001 X.
If the analyzer itself is installed in Ex Zone 1, then a certified EEx P purge and pressurization device
must be used to deliver protective gas to the analyzer, typically air taken from a non-hazardous zone,
or an inert gas, and to disconnect the power supply and other electrical connections when the purge
is not active or fails. The EEx p safety device must conform to all applicable codes, including EN
50016. It should also meet the requirements listed here:
1. The purge apparatus and analyzer instruction manuals must be read, understood, and followed.
2. All seals of the analyzer housing must be in place and in good condition. Suitable cable glands for
wiring must be installed and properly sealed. All seals must be inspected in regular intervals to
ensure proper operation. Seals showing signs of wear or leakage must be replaced.
3. The analyzer must be connected to earth ground using the connector on the exterior of the
enclosure.
4. The inlet for the protective gas at the analyzer is a ¼ inch compression fitting. The outlet is a 3/8
NPT thread. The tubing between the outlet at the analyzer and the purge system must provide a
suitable inner diameter that ensures that the pressure drop across that tubing is at most 5 hPa.
5. Before any electrical circuits in the analyzer enclosure, including input and output connections to
other devices, are energized, an initial purge must be made for a minimum of ten minutes, at a
flow of not less than 24 liters per minute. Thereafter a minimum purge flow rate of not less than
14 liters per minute shall be maintained. A minimum pressure of 0,5 hPa must be maintained
during the initial purge, and thereafter for as long as circuits remain energized. The maximum
pressure of 25 hPa must not be exceeded. These pressures are measured relative to the ambient
pressure exterior to the analyzer enclosure.
6. If either the continuous purging or pressurization of the analyzer enclosure fails, the purge
equipment shall give an alarm, and in the case of Ex Zone 1 installations, shall, via Ex-coupling
relays, automatically remove power from all circuits in the analyzer enclosure except those which
are intrinsically safe.
PrevEx®InstructionManual
3
INTRODUCTION
7. The analyzer has flame arrestors to prevent flashback through the sample and exhaust tubing.
They must be kept in place at all times. The flame arrestors must be replaced if they show any
sign of mechanical damage that might reduce their effectiveness. The flame arrestors must never
be cleaned with an abrasive.
8. The fuel pressure delivered to the analyzer must not exceed the maximum specified pressure as
given in the analyzer instruction manual. A relief valve should be provided at the fuel source to
prevent overpressure of the fuel supply to the analyzer.
9. The fuel inlet fitting, part number SNP374 supplied with the analyzer contains a restrictor element
that limits the maximum flow of fuel into the analyzer housing during failure of the fuel
containment system. This fitting must be kept in place at all times. It should never be cleaned
with an abrasive or mechanically damaged. If it becomes contaminated, or is otherwise damaged,
it must be replaced only by the same part number.
10. The internal fuel delivery system of the analyzer is assembled using stainless steel capillaries with
stainless steel compression fittings. Care must be taken to ensure that the fuel system is not
damaged and is free of leaks.
4
Control Instruments Corp.
INTRODUCTION
1.5.
Models
A permanent serial plate (nameplate) is mounted on the lower right side of the
analyzer. It contains the model number, serial number, ratings, and the approval
mark, if any. Models have differences based on requirements for performance and
hazardous locations from their respective approvals. Some models include an
overtemperature thermostat. In particular, purging and pressurizing the enclosure
for installation in hazardous areas varies between models. Installation in Ex Zone 1
or Division 1 areas requires an additional purge device.
Models suitable for hazardous locations may also be installed in non-hazardous or
general-purpose locations without an additional purge device.
1.5.1.
FMc and FM Models
Canadian Standards
Association
(FMc)
Factory Mutual Research
(FM)
Generic Label
Models with generic labels have options not
tested and approved by a third party.
FM and FMc approved models are suitable for installation in Class I Division 2 hazardous locations and for
sampling from Class I Division 1 hazardous locations. Installation in a Class I Division 1 hazardous location
requires the addition of an approved purge device. Generic types require case-by-case evaluation.
TYPE Y PURGE DEVICE
Indicator and alarm for loss
of purge or pressurization.
K
K
FM/FMc TYPES
Installed in non-hazardous
location, or in Class I
Division 2 hazardous
locations - no additional
purge device required.
A
B
C
D
E
PrevEx®InstructionManual
F
G
FM/FMc TYPES
Installed in Class I
Division 1 hazardous
locations
A
B
C
D
E
F
G
5
INTRODUCTION
ATEX (CENELEC) and CE Models
1.5.2.
II 2 G EEx p II Tx
-20°C < Tamb < 60°C
Control Instruments Corporation
Fairfield, New Jersey, USA
0344
Model
SNR67XXXX
Free volume
18 l
Freies Volumen
Year of manufacture
XXXX
XX-XXXX
Minimum overpressure
0,5 mbar
Mindest- Überdruck
Serial number
Maximum overpressure
25 mbar
Maximaler Überdruck
Certificate number
DMT 03 ATEX G 001 X
Voltage
Fuel type
□ 230 VAC
x Hydrogen
□
□
Minimum purge volume
240 l
Mindest-Vorspülmenge
120 VAC
Minimum initial purge flow
24 l/min
Mindest-Vorspül-Volumenstrom
Propane
Minimum continuous dilution flow
14 l/min
Mindest-Volumenstrom
Models SNR67x-Ty where x is 1,2,4 or 5 and Ty is the temperature rating carry the ATEX and CE marks. The
label includes the year of manufacture, the ratings, and purge information needed for installation in Ex Zone 1 or
Ex Zone 2 hazardous locations in conformance with CENELEC EN50014, -016, and -018 norms of the ATEX
directive 94/9/EC. A latching safety thermostat with manual reset is installed to prevent overtemperature. It
removes power from the heater so the temperature does not exceed the T rating of the analyzer.
ATEX Model Number designations and T ratings
Model
Number
Designation
Normal
Operating
Temperature
Overtemperature
Safety Thermostat
Setting
IEC 79-8
T Rating
SNR671-T6
SNR672-T4
SNR672-T3
SNR674-T3
SNR674-T2
SNR675-T2
60°C
100°C
120°C
180°C
200°C
250°C
82°C
118°C
200°C
200°C
300°C
300°C
T6
T4
T3
T3
T2
T2
ATEX Purge Configurations
K
K
VENT
VENT
ATEX TYPE IN NON-HAZARDOUS AREA
ATEX TYPE IN Ex-ZONE 1
A
B
C
D
E
F
G
A
B
C
D
E
F
G
PURGE INLET
PURGE AIR INLET 1.4 BAR
APPROVED EeX d
PURGE DEVICE
6
To convert between ATEX types, switch plug
and fitting between inlets C and F, and
install/uninstall vent fitting at K.
Control Instruments Corp.
THEORY OF OPERATION
2.
Theory of Operation
2.1.
Hazards of Flammable Gases and Vapors
The hazards of flammable gases and vapors are fire, explosion, and toxicity. The PrevEx analyzer
does not protect against short or long-term toxicity and toxic effects. It is designed to give early
warning of the possibility of fire and explosion.
2.1.1.
Lower Flammable Limit - LFL
The Lower Flammable Limit (LFL), is the leanest mixture of gas or vapor in air, that, when ignited,
will continue to burn even after the source of ignition is removed. This means that a combustion
wave, or ―flame front,‖ can travel through the mixture, releasing energy as it moves, and continuing
on its own. It is possible that the combustion wave can travel long distances through the mixture,
back to the source of the vapors, and cause a fire. At concentrations above the LFL, the mixture can
rapidly increase in speed and the amount of energy it releases as it burns, to the point where it can
cause very high pressures and an explosion. This is why the Lower Flammable Limit is sometimes
called the Lower Explosive Limit (LEL), an older term used interchangeably with LFL.
Each flammable gas has its own LFL value, the percent by volume concentration in air at which that
particular gas becomes flammable. At concentrations below the LFL, there is not enough flammable
gas to propagate a combustion wave. By keeping an atmosphere below the LFL, it is possible to
isolate sources of ignition from sources of combustion, preventing a flame front from traveling back
to the source of vapor or gas and creating a fire or explosion.
There is also an Upper Flammable Limit (UFL), which is the richest mixture of gas or vapor in air
such that the ignited mixture will continue to burn after the source of ignition is removed. At
concentrations above the UFL, there is not enough air in the mixture to propagate a combustion
wave. But once additional air is added to the mixture, it becomes flammable or explosive. The
monitoring of mixtures having high concentrations above the UFL requires special considerations
that are beyond the scope of the use of this device. In the use of this analyzer, all concentrations
above the LFL should be treated as if they were flammable and explosive.
2.1.2.
%LFL Readings
This device measures flammability in the range from ―zero‖ air that is free of flammable gas, up to
the LFL. The measuring scale is divided into percentages of the LFL, so that 0%LFL means that no
flammable gas is present, and 100% LFL means that the Lower Flammable Limit has been reached.
Laws for industrial processes typically forbid operation above 50% LFL, and require an immediate
response to protect life and property when the flammable gas concentration exceeds 50% LFL.
WARNING! Readings above 50% LFL indicate a potential hazard to life and property.
2.1.3.
Flash Point
The Flash Point is the temperature at which a flammable liquid gives off enough vapor to form an
ignitable mixture with air. The liquid can form an invisible, explosive ―cloud.‖ Many flammable
liquids have flash points at or below ordinary ambient temperatures. These will ignite immediately if
a source of ignition is brought anywhere near the liquid. When the Flash Point is below the ambient
temperature, vapor that forms above the surface of the liquid can very easily travel through the air,
away from the spilled liquid, until a source of ignition is reached. The ignited vapor cloud can
explode, or it can flash back to the liquid and explode, or it can ignite the surface of the liquid itself
and cause a fire.
Liquids with Flash Points above ordinary ambient temperatures can still form hazardous vapor
mixtures when heated, and can condense back into liquid when cooled. For accurate measurement,
PrevEx®InstructionManual
7
THEORY OF OPERATION
every part of the sampling system and sample tubing must be heated above the Flash Point.
Otherwise, condensation prevents flammable vapors from reaching the analyzer. Even a very short
section of tubing, at a temperature just below the flash point, can disable the measurement2.
2.1.4.
Autoignition
Sufficiently heated, a flammable gas mixture can spontaneously ignite. The auto ignition temperature
(AIT) is the lowest temperature at which a flammable vapor spontaneously ignites. The AIT varies
for each type and concentration of gas, but usually occurs at the stoichiometric concentration (perfect
combustion). Heating a mixture to the AIT can cause a fire or explosion, sometimes after a time
delay up to a few minutes. In effect, heated flammable gases are more flammable.
2.1.5.
Temperature Dependence
Because heating a flammable gas makes it more flammable, a mixture below the LFL at one
temperature can exceed the LFL when heated. For accurate measurement of heated processes, this
temperature dependence must be included in the analyzer calibration. Regulations may require an
increase in sensitivity of either 7.8% (USA) or as much as 14% (CENELEC) for every 100ºC
increase in temperature.3
2.2.
Measuring Principle
A sample is drawn into the analyzer‘s flame cell. Flammable gases and vapors in the sample are
burned in the sensing flame. A thermocouple located directly above the sensing flame converts the
resulting temperature rise into an electrical signal, which is proportional to the concentration of
flammable gas from 0 to 100% of the Lower Flammable Limit (LFL or LEL).
Sensing flames in a hydrogen-fueled analyzer. Flame size and thermocouple temperature increase from low (upper left) to
high flammability (lower right - where a flame front is visible).
2
Small temperature changes have a large effect on the concentration. A temperature drop as little as 10°C below the flash
point can cause false low readings from condensation and prevent an alarm. For many solvents, near the flash point the
maximum (saturation) vapor concentration is reduced 50% by a -10°C reduction in temperature.
3
It is important to note that the temperature dependency of flammability is not a physical influence on the analyzer‘s
reading or its principle of operation. Because it is thermostatically heated, the analyzer does not respond to changes in the
temperature of the atmosphere being monitored. Nor is the temperature dependency of flammability due to the expansion or
contraction of air. It is an effect that changes the chemical and thermodynamic properties of the flammable gas mixture.
8
Control Instruments Corp.
THEORY OF OPERATION
2.3.
Flame Cell and Sensing Flame
Flammability measurement occurs in the flame cell, where a small ―sensing flame‖ sits on a burner
tube. A sample is continuously drawn in through a sample tube by suction produced by an air
aspirator. The aspirator runs from a regulated supply at constant pressure on the air inlet.
Flammables in the sample burn in the sensing flame and produce a temperature rise, proportional to
the Lower Flammable Limit, in a thermocouple that is located above the flame. The sample gases are
then exhausted through the aspirator and exit through the exhaust tubing.
The sensing flame is ignited by a discharge from a spark electrode to the grounded burner tube. It is
maintained by a constant flow of fuel to the burner. A fuel regulator feeds constant pressure through
a sintered metal restrictor inside the base of the burner tube to produce a stable flame with a constant
temperature in the absence of flammable gases in the sample.
The flame cell has inlet and exhaust flame arrestors to prevent propagation of the sensing flame out
of the flame cell. They must be kept clean and properly installed at all times. They should never be
subjected to mechanical abuse or cleaning with abrasive substances. They should be replaced if they
show signs of wear or damage. Disposable filters inside the inlet and exhaust flame arrestors keep
the sensor flow paths clean.
WARNING! Always operate the analyzer with undamaged flame arrestors in place.
The sample flow is measured as it exits the flame cell. An orifice located behind the small sintered
metal filter produces a pressure drop proportional to the flow rate. The pressure drop is measured by
a transducer in the controller. If the sample flow rate decreases, a message is given to check the flow.
If it continues to decrease, a ―Low Flow‖ fault is activated.
Front view of flame cell with cutaway
exposing the internal parts. The flame
arrestor caps can be seen along the left
edge. Adjacent to the caps are the flame
arrestors, positioned at the top and bottom
of the flame cell. Directly in the center is
the spark plug. The thermocouple is above
the spark plug and the burner is below.
PrevEx®InstructionManual
Rear view of flame cell and aspirator block with
cutaway showing the location of the aspirator and
flow paths. An aspirator nozzle sits inside the block.
Compressed air passing through the aspirator creates
suction that draws sample flow through the flame
cell.
9
THEORY OF OPERATION
2.4.
Flow Diagram
CONTROL INSTRUMENTS CORPORATION - PREVEX FLAMMABILITY ANALYZER - INTERNAL FLOW SCHEMATIC
FIXED ORIFICE
"SAMPLE FLOW"
FO1
AF4
AIR FILTER
"ORIFICE"
EXHAUST OUTLET
K
ENCLOSURE
PURGE
EXHAUST
M
AF2 AIR FILTER
ATEX and CENELEC types
TUBE
#1
(RED)
"EXHAUST"
for Ex Zone 1
have 3/8 inch pipe fitting
FA2 FLAME ARRESTOR
with 1/2 inch open ID.
Other types have 1/4 tube
OPD+
FLAME
CELL
fitting with restrictor inside.
TUBE
#2
(BLACK)
25 LPM
1 SCFM
OPD-
PE1
PRESSURE TRANSDUCER
"ORIFICE PRESSURE"
(Located inside controller)
FA3 FLAME ARRESTOR
FE
VENTURI
"ASPIRATOR"
"INLET"
SAMPLE FLOW
2 LPM TYPICAL
AF1 AIR FILTER
FO3
FIXED ORIFICE
"FUEL RESTRICTOR"
SAMPLE INLET
L
Excess flow exits
during calibration
FUEL FLOW
FLAME CELL, HEATED ENCLOSURE
CONTROLS, UNHEATED ENCLOSURE
CALIBRATION
FLOW
3.3 LPM
7 SCFH
PCV1
"FUEL REGULATOR"
PRESSURE
CONTROL VALVE
AF3
FUEL
FILTER
Inside inlet fitting
10
DILUTION AIR FLOW
(OPTIONAL)
FO4
FIXED ORIFICE
"AIR DILUTION"
PCV2
REGULATOR
"AIR DILUTION"
(OPTIONAL)
FO5
FIXED ORIFICE
"CALIBRATION"
SV-1
SOLENOID VALVE
"SPAN"
SV-2
SOLENOID VALVE
"ZERO"
FO2
HOUSING
PURGE
(see notes)
Inside inlet fittings
FUEL INLET
"HYDROGEN"
"PROPANE"
40 TO 45 PSIG 30 TO 35 PSIG
2.8 TO 3.1 BAR 2.0 TO 2.4 BAR
DILUTION INLET
20 PSIG 1.4 BAR
INSTRUMENT AIR
(OPTIONAL)
REFERENCE PORT
"HOUSING PURGE
PRESSURE"
(OPTIONAL)
A
B
C
INLET IDENTIFICATION
SPAN INLET
20 PSIG
1.4 BAR
D
ZERO INLET
20 PSIG
1.4 BAR
E
ATEX types in EX Zone 1 have inlet F
plugged and FO2 unused, with purge
supplied at inlet C.
ATEX types in non-hazardous locations
use inlet F and FO2 for purge.
All other types have internal
connection from inlet G to FO2 with
inlet F plugged.
PURGE
AIR INLET
20 PSIG
1.4 BAR
(see notes)
COMPRESSED
AIR INLET
20 PSIG
1.4 BAR
F
G
Control Instruments Corp.
THEORY OF OPERATION
2.5.
Electrical Diagram
Thermocouple TC2, Type K
"HSG TEMP"
Heater control
Thermocouple TC1, Type K
"FLAME TEMP"
Main Signal
BLOCK HEATER
SPARK
ELECTRODE
SENSING FLAME
HEATER / ASPIRATOR BLOCK
FLAME CELL
RED (-)
RED (-)
YELLOW (+)
YELLOW (+)
SAFETY THERMOSTAT
ATEX / CENELEC TYPES
OPEN-ON-RISE
TO MEET T-RATING.
MANIFOLD
AC INPUT POWER
400 WATTS Maximum
SPAN
See nameplate for rating
Lug
Ground / Earth
Neutral
Hot / Line
Type F
Type T
AC POWER
5 x 20mm FUSES
0,5 A
5A
OR JUMPER
THERMOSTAT
HEATER
GROUND
SPAN
CAL IN
PROGRESS
ZERO
24 25 26 27 28 29 30 31 32 33 34 35 36 37
VALVE
HORN OR
AIR/FUEL
WARNING
DANGER
FAULT
NEEDED
11 12 13 14 15 16 17 18 19 20 21 22 23
SERVICE
Ground
+ 485 Data +
Ground
9 10
PORT
8
RS 485
7
SERIAL - 485 Data -
6
4-20 Signal
5
4-20 mA
OUTPUT
4
CONTROL 1
No connection
3
COMMON
2
CONTROL 2
1
No connection
ZERO
RELAY CONTACTS ARE SHOWN IN THE DE-ENERGIZED STATE.
IGNITION
CABLE
PrevEx®InstructionManual
CONTACT RATING IS 60 WATTS (VA) MAXIMUM NON-INDUCTIVE.
11
THEORY OF OPERATION
2.6.
The Controller
The controller is an electronic measuring and control device mounted inside the sensor enclosure. It
conditions and converts signals from the thermocouples and transducers, and performs control,
alarm, and output functions. The controller makes the flammability reading, controls alarms,
regulates the flame cell temperature, monitors the sample flow, and generates faults if it detects
improper operation. It amplifies the thermocouple signal and performs digital signal processing to
obtain a final calibrated flammability reading in percent of the Lower Flammable Limit. It controls
two level alarms: a ―high‖ alarm (warning), and a ―high high‖ alarm (danger). It outputs the reading
and status of the sensor by means of indicators, electromechanical relays, a 4 to 20 milliamp output,
and a serial port.
Flame
Cell
Controller
FAULT
DANGER WARNING
HORN
ZERO
SPAN
IGNITE
HEAT
Front view of typical analyzer, shown with cover(s) removed. The controller is in the lower,
unheated section. Pneumatic controls are behind the controller. Pneumatic and electrical
connections are at bottom.
2.6.1.
Control of Flame Cell Temperature
An electric heater embedded in the sampling system keeps the flame cell temperature constant. The
temperature setting is found in the SET TEMP register on the GAUGES menu. A type K thermocouple,
called TC2, also embedded in the sampling system, produces the HSG TEMP reading on the GAUGES
menu. During warm-up the HEATER indicator is on continuously until the temperature is within a
few degrees of the setting, and then it cycles on and off to control the temperature to the setting.
WARNING!
2.6.2.
Keep the analyzer heated to prevent condensation that could cause false low readings.
Monitoring Sample Flow
The pressure across the sample flow orifice is measured and converted to FLOW on the GAUGES
menu, in standard liters per minute (LPM) sample flow. The orifice may require periodic cleaning to
keep it clean and accurate. A reduced flow rate will slow down the response time of the sensor.
12
Control Instruments Corp.
THEORY OF OPERATION
2.6.3.
Making the Flammability Reading
A type K thermocouple, called TC1, passes through the wall of the flame cell and is bent in a 90°
angle directly over the sensing flame, so that the tip of the thermocouple can measure the heat given
off. This signal is the FLAME reading on the GAUGES menu, and, when captured during the
calibration process, it is also the RAW ZERO and RAW SPAN reading on the CAL MENU. When the
FLAME temperature equals the RAW ZERO, the reading is 0%LFL. When FLAME is equal to RAW
ZERO plus RAW SPAN, the reading is equal to CAL RDNG from the CAL MENU. Other FLAME
temperatures produce proportional flammability readings.
2.6.4.
Calibration
Calibration uses two test gases: ―zero‖ air with no flammables, and ―span‖ gas containing a known
concentration of flammables. Zero calibration sets the reading to 0 %LFL. Span calibration sets the
reading to the CAL RDNG, for example 60% LFL. Zero and span solenoid valves automate
calibration. When the solenoid valve energizes, pressurized test gas flows into the flame cell,
completely filling it, with some excess gas flowing backwards out the sample inlet.
2.6.5.
Calibration and Reading Calculations
First, Zero Gas, air completely free of flammable gases, is injected to the flame cell. After a minute
or more, the FLAME temperature is captured as the RAW ZERO, which makes the reading 0% LFL.
Next, span gas is injected. It has a known flammability concentration, called the calibration reading
(CAL RDNG). After a minute or more, the FLAME temperature minus the RAW ZERO is captured as the
RAW SPAN, which makes the reading equal to CAL RDNG. Every ¼ second, a new reading is made by
comparing the FLAME temperature to the RAW ZERO and RAW SPAN.
RAW ZERO = FLAME temperature measured while sensor is exposed to Zero Gas
RAW SPAN = (FLAME – RAW ZERO), measured while sensor is exposed to Span Gas
%LFL Reading ((FLAME – RAW ZERO) / RAW SPAN) x LAST CAL RDNG
LAST CAL RDNG
LAST CAL RDNG
is a copy of the CAL RDNG setting saved during the last successful calibration. The
is used to make the reading, so that a change to the CAL RDNG setting has no
immediate affect on the readings until a calibration is performed.
2.6.6.
Warning and Danger Alarms
When the flammability exceeds the WARNING or DANGER settings in the ALARMS menu, the
corresponding alarm and relay is activated. Once activated, the alarms latch, and stay activated until
they are manually RESET. If an external device provides the latching function, then alarms can be set
to automatically reset, by turning off the LATCHES setting in the ALARMS menu. Then if the reading
returns to normal, the alarm indicator and relay are automatically deactivated. If the DANGER alarm
is not latching, an external device must be used to provide the latching function.
When both alarms are active, but their settings differ, the DANGER setting controls the WARNING.
While is DANGER latched, WARNING will also latch. When DANGER autoresets, WARNING will also
autoreset – if the reading is below the WARNING level at the moment DANGER autoresets.
If the DANGER alarm is active, the analyzer is indicating a hazardous concentration of gas, even
though the FAULT alarm and indicator might also be active at the same time. Never ignore a DANGER
alarm. Faults such as flameout can occur from an explosive concentration of gas.
WARNING!
Simultaneous FAULT and DANGER alarms may indicate an explosive atmosphere.
PrevEx®InstructionManual
13
THEORY OF OPERATION
WARNING
and DANGER settings should be made as low as possible without giving false alarms.
Therefore, if the maximum expected concentration is, for example, 10%LFL, an alarm at 15%LFL is
faster and more effective.
2.6.7.
Rate-of-Rise Alarm
When the flammability reading is increasing fast enough to exceed the danger alarm, the danger
alarm is activated, even if the danger level has not yet been reached. This feature can be enabled or
disabled using the RATE register in the ALARMS menu.
2.6.8.
4 to 20 Milliamp Output Signal
The flammability reading is converted to a 4 to 20 milliamp output signal, where 4 milliamps
represents 0% LFL and 20 milliamps represents 100% LFL. Registers for 4MA ADJ and 20 MA ADJ in
the OUTPUTS menu are used to correct for small amounts of electronic error in the output circuit. The
milliamp signal can go below 4 milliamps and above 20 milliamps.
For readings below 0% LFL, the signal is reduced below 4 milliamps, until it reaches 2.0 milliamps
(-12.5%LFL). The signal does not go below 2.0 milliamps unless there is a misadjustment of the 4MA
ADJ register, or a loss of power, or a disconnected wire.
During calibration, or during faults, the signal can be forced to a special value. The MA CAL register
on the OUTPUTS menu defines the value of the signal during calibration. The register MA FAULT on
the same menu defines the signal during faults.
WARNING!
The 4 to 20 milliamp output is not failsafe under all conditions. Always use both the
and DANGER relays in addition to the milliamp output.
When electrical power is first applied to the analyzer, the milliamp output circuit can temporarily
output a high milliamp signal for a short time until the circuit stabilizes.
FAULT
Some monitoring devices do not accept readings below 4 milliamps. In this case the register 4MA
ADJ can be used to offset and scale the output signal. For example, to change the output so that 4
milliamps is output at -5%, increase 4MA ADJ by +0.8 milliamps. An output of 4.8 milliamps now
corresponds to 0%, and full scale remains unchanged at 20 milliamps. This change of scale can allow
small negative readings to be accepted. The total amount of adjustment of 4MA ADJ cannot exceed
+/- 2.0 milliamps.
2.6.9.
Serial Communications
An RS 485 serial port with Modbus RTU protocol allows remote monitoring of display and control
functions.
2.6.10.
“Service Needed” and Faults
If operation is not within the optimal range, but the problem is not yet severe enough to be a fault, a
‖Service Needed‖ message and relay activation occurs. The analyzer can still be operated, and can
give warning and danger alarms. Service needed gives maintenance personnel the opportunity to
correct a problem before it becomes a fault.
If operation is not within the acceptable range, a fault is given. During faults, warning and danger
alarms are disabled. The analyzer must be serviced immediately to restore proper operation. If more
than one fault exists at the same time, the most serious fault is displayed. If, during the power-on
self-test, a fault is found that prevents continued operation, the controller attempts to put the outputs
into a failsafe condition. The red ―alarm‖ LED indicator is turned on, and the green ―scan‖ LED
indicator is turned off. Under some type of faults, the controller may continually reset itself.
14
Control Instruments Corp.
THEORY OF OPERATION
2.6.11.
Air/Fuel Cutoff function of the HORN relay
The RLY CNFG settings in the OUTPUTS menu allows the horn relay to control the supply of fuel, and
in some cases also the supply of air, to the analyzer.
When RLY CNFG is set to AIR FUEL, the relay is energizes immediately when power is turned on. It
de-energizes if one of the follow conditions occur:
1. A FLAMEOUT exists for more than fifteen minutes after the last ignition attempt.
2. The HSG TEMP is too low for normal operation of the analyzer.
There is a fifteen minute delay in the activation of the Air/Fuel cutoff. Turning power on, a RESET
command, or automatic ignition attempts will keep the relay energized for at least fifteen minutes.
The Air/Fuel cutoff function has two purposes:
1. Turn off fuel when the flame is not operating properly: A leak in the fuel supply, or the
absence of compressed air pressure, will likely cause flameout. Use the relay to shut off the
flow of fuel to the analyzer, as added protection against the accumulation of fuel in the
analyzer housing
2. Prevent clogging of the analyzer from solid condensates: An analyzer that is not up to
temperature can cause condensation. In rare cases a high temperature process might contain
vapors that could condense into solids if they are cooled in an analyzer that is not up to
temperature. Use the relay to shut off BOTH the flow of fuel to the analyzer AND the flow
of compressed air to the analyzer so that the flow of sample into the analyzer stops when the
analyzer is cold.
Note: There is still the chance that vapors can diffuse into the analyzer and condense. The
use of the Air/Fuel cutoff can delay, but not completely prevent, clogging of the analyzer
from solid condensates.
When RLY CNFG is HORN, an ignition cutoff feature (in VERSION 5.20 and above) is enabled.
Ignition cutoff prevents ignition of the sensing flame when the compressed air supply is
turned off, or has recently been off (if FLOW is at or below 0.4 LPM). It lasts as long as the
lack of flow lasted, up to ten minutes maximum. During ignition cutoff, automatic reignition attempts (see setting AUTO IGN) are skipped.
Ignition cutoff extends the WARMUP state from 45 seconds up to ten minutes, or until all
conditions are normal (flame, flow, temperature), which gives extra time for the analyzer
enclosure to purge before ignition.
When RLY CNFG is AIR/FUEL or OVERRIDE, there is no ignition cutoff.
Use the AIR/FUEL setting only if a solenoid valve is installed that automatically shuts off
the fuel supply when the compressed air supply is turned off, or when an approved purge
system is attached to the analyzer enclosure.
The OVERRIDE setting requires a manual shutoff of the fuel whenever the compressed air
supply is turned off. The OVERRIDE setting should only be used by a trained technician
during maintenance or troubleshooting activities.
WARNING!
Keep air pressure supplied to the analyzer whenever fuel pressure is present. If the
compressed air is to be cut off, the fuel must also be cut off.
PrevEx®InstructionManual
15
THEORY OF OPERATION
2.6.12.
Flameout
WARNING!
Flameout may indicate the presence of an explosive atmosphere.
FLAME temperatures below 450°C (~ readings below -35% LFL) indicate flameout. The flame may
be out entirely, or too weak for valid measurements. As flameout is detected, a two-second IGNITION
pulse causes a spark discharge to the burner tube to re-ignite the sensing flame. If IGNITION is
successful, a RESET command can be used to clear the fault indicator and relay. If the attempts fail, a
RESET command will repeat ignition. If the AUTO IGN register is set to 1 or more, there will be that
number of re-ignition attempts at 15-second intervals – if this re-ignition is successful, and there are
no other faults, the flameout fault will be cleared, regardless of the LATCHES setting.
2.6.13.
Flameout from Flammable Mixtures - Flooding
If flameout follows a danger alarm, the flameout is probably from flammable gas above 100% LFL.
The special state of ―flameout subsequent to a danger alarm‖ is called flooding.4
WARNING!
Flooding may indicate the presence of an explosive atmosphere.
While in this special state:
The WARNING and DANGER alarm indicators and relays are active.
The milliamp output is forced to 20 milliamps.
The FAULT alarm indicator and relay are inactive, unless a fault other than flameout occurs.
The display indicates ―DANGER - FLOODED - 100% LFL‖
The READING register may be invalid, for example a reading of –99% LFL.
While in this special state, if another type of fault (not flameout) occurs:
The WARNING and DANGER and FAULT alarm indicators and relays are active.
The milliamp output is either:
a) 20 milliamps, if the MA FAULT register is set to ―OFF.‖
b) forced to the value programmed into the MA FAULT register.
The display indicates ―DANGER - FLOODED - 100% LFL‖
The READING register may be invalid, for example a reading of –99% LFL.
The analyzer will recover from this special state by ignition of the sensing flame.
Recovery from the special state following automatic re-ignition:
If the DANGER alarm is not latched in the LATCHES register, and the AUTO IGN setting is
nonzero, the analyzer will attempt a series of re-ignition attempts. If ignition is successful,
and there are no faults of any kind, and the reading is below the alarm settings, then the
alarms will clear and the analyzer will return to NORMAL status.
Recovery from the special state following a RESET command:
The FAULT alarm indicator and relay are active.
The WARNING and DANGER alarm indicators and relays are inactive.
The milliamp output is either:
a) 20 milliamps, if the MA FAULT register is set to ―OFF.‖
b) forced to the value programmed into the MA FAULT register.
The display is ―FLAMEOUT‖ and the reading may indicate –99% LFL until the flame is lit.
The READING register is invalid, for example a reading of –99% LFL, until the flame is lit.
4
Sudden increases above 50% by volume per second can prevent the FLOODED state in analyzer types K and D.
16
Control Instruments Corp.
THEORY OF OPERATION
2.7.
Air Dilution Option
Air dilution is a factory-installed option that injects air in the sample flow to improve accuracy and
prevent flameout over a wide range of sample oxygen concentrations. Half the flow into the flame
cell comes from the sample, the rest is dilution air from a pressure regulator. Added air keeps the
oxygen concentration in the flame cell high enough for the flame.
Identification of air dilution models
Air dilution models contain option #OPT353HP. Their TYPE contains the letter D or K as in
SNR674D. They have a dilution air inlet (B) and dilution air regulator PCV2. For VERSION 5.12 and
above, the burner is part number BRN050, and the gap between the burner and thermocouple is 0.5
inches (1.3 cm).
Installation of air dilution models
Connect 20 PSIG (140 kPa) clean, dry ―instrument grade‖ compressed air to the air dilution inlet
―B.‖ Compressed air quality will affect accuracy. It must be free of oil and condensed water to
prevent flow problems and false readings. A shut-off valve at the Dilution Air Inlet is required.
Protect inert processes from dilution air in the analyzer‘s exhaust. Make certain that exhaust air
cannot adversely affect an inert process, or take special precautions for the exhaust method.
Oxygen Effects5
Readings increase approximately +0.7%LFL for each -1% by volume reduction in oxygen
concentration in the process being monitored.
Calibration of air dilution type analyzers
Calibration gases are also diluted. To maintain
accuracy, the FLOW during the span calibration
should be monitored to ensure that it matches the
FLOW during sampling.
Air Dilution Option
Option #OPT353HP
Checking for leaks
To perform leak checks as indicated in the
maintenance procedures, a valve on the Dilution
Air Inlet (B) must installed, so it can be shut for
the duration of the test.
Alignment
The burner is aligned 0.5 inch (1.3cm) directly
beneath the thermocouple, a gap twice as large as
the standard analyzer. The spark electrode is
aligned normally, directly behind and slightly
above the burner. Typically the alignment does not
require adjustment unless the flame cell has been
opened for maintenance.
5
Dilution air adjustment
and lock nut.
PCV2 Dilution Air Regulator
Part number PRV069
FO4 Fixed Orifice
Dilution Air Flow Restrictor
Part Number SNP436
B
Dilution Air Inlet
Instrument Air
20 PSIG (1,4 bar)
See section 3 for important specifications: response time, pressure, oxygen, and flow effects.
PrevEx®InstructionManual
17
THEORY OF OPERATION
Tuning the dilution air regulator – option #OPT353HP
The dilution air regulator is factory-tuned so that the ratio of sample to dilution air is one-to-one. It
does not normally require adjustment.
This procedure tunes the dilution air regulator to get 50% sample and 50% air. Use only for VERSION
5.12 and higher. Use with burner BRN050, having a 0.5 inch (1.3cm) gap between the burner and
thermocouple.
1. Start with cover on and analyzer stable.6
2. Shut off pressure to the air dilution inlet only. This requires a shutoff valve at the air dilution
inlet.
3. Open the cover, and perform the following as quickly as possible.
4. Set CAL TIME in CAL MENU to 4 minutes.
5. Record the FLAME reading in air from the GAUGES menu.
6. Initiate a SPAN TEST with 1.15% Ethylene7 in Air.8,9
7. After one minute, record the FLAME reading for 1.15% Ethylene without dilution.
8. With SPAN TEST still active, turn on pressure to the air dilution inlet.
9. With SPAN TEST still active, adjust the dilution air regulator10 to get a FLAME reading of:
For 0.50 inch gaps11, FLAME = 62% of FLAME reading in air (step 5) plus 38% of FLAME reading
for 1.15% Ethylene without dilution (step 7).
10. At the end of span test, return CAL TIME in CAL MENU to 1 minute.
11. Replace the outer cover.
12. Wait for analyzer to stabilize.
13. Perform a FULL CAL from the COMMANDS menu using a flashlight (keep cover on).
14. For SPAN FAIL faults, SPAN°C may require adjustment.
6
The analyzer should be checked regularly for leaks. Analyzer leaks cause reading errors. Only leak-free
analyzers should be operated or adjusted.
7
Alternate calibration gas, 0.91% Propane, may also be used.
8
Misalignment can cause errors similar to incorrect span calibration gas.
9
Accuracy will depend completely on the accuracy of the span calibration gas.
10
Following this calculation results in a RAW SPAN that is 45% of the RAW SPAN without air dilution for
0.25‖gaps, and 38% for 0.5‖ gaps.
11
For 0.25 inch gaps, FLAME = 55% of FLAME reading in air (step 5) plus 45% of FLAME reading for 1.15%
Ethylene without dilution (step 7), if for some reason a 0.25 inch (6.4mm) burner-thermocouple gap is in use.
18
Control Instruments Corp.
THEORY OF OPERATION
2.8.
Fail-safe Considerations
Safety equipment must give continuous protection. It should notify the operator of failures that might
disable protection. The analyzer continually checks itself, and can detect many types of faults.
During faults the reading is not reliable, and the warning and danger alarms are disabled. Processes
that depend on the analyzer for safety must have the FAULT relay hard-wired to the safety shut down.
WARNING!
WARNING!
During faults, the warning and danger alarms are disabled. Because the proper function of
the analyzer is required for safety, the FAULT relay must be used to initiate a safety
shutdown or equivalent corrective actions suitable to the process or area being monitored.
Not all faults are detectable. Investigate unusually low readings. Perform regular leak
checks. Abnormal behavior must be recorded, investigated, and resolved.
Incorrect calibration gas type or concentration causes significant errors. The calibration gases should
be tested and certified within a tolerance of +/-2% or less prior to use. The RAW ZERO and RAW
SPAN should be monitored for significant changes, especially for a new calibration gas cylinder.
Keep the old cylinder as a reference until the new cylinder is verified. The RAW SPAN for both
should be within the cylinder‘s stated tolerance, not more than 4% cumulative error.
WARNING! Calibration gas must be the correct type and concentration for valid readings and alarms.
Certain types of leaks in the sampling system might not be detected unless a thorough leak check is
performed. Unusually low readings could be caused by a leaking sampling system.
2.8.1.
Oxygen Concentration
The sensing flame gets its oxygen from the sample. Oxygen deficiency causes exaggerated readings.
Standard hydrogen-fueled analyzers are accurate to at least 12% by volume oxygen and flameout
occurs suddenly at about 7% oxygen. Propane-fueled analyzers are affected much more by oxygen
deficiency, and should be operated above 18% by volume oxygen. Air dilution type analyzers do not
flame out from oxygen deficiency. See section 2.7.
WARNING! Low-oxygen atmospheres can prevent proper operation of the analyzer.
Oxygen enriched atmospheres cause a decrease in the analyzer reading of approximately –1% LFL
per percent oxygen. Concentrations above 25% by volume oxygen require special precautions that
are beyond the scope of this device and manual. In addition, special precautions for electrical safety
must be observed when the possibility exists for oxygen-enriched atmospheres.
2.8.2.
Flammable Concentration Limits
Very high concentrations, at or above the LFL, can extinguish the sensing flame. Up to the point of
flame out, the readings increase, and then suddenly drop downscale.
2.8.3.
Speed of Response
Effective alarms require a fast analyzer and immediate corrective action. Keep sample lines short.
Use low-diameter tubing. Do not add extra sample filters. Corrective action must quickly reduce the
flammable gas concentration to a minimum. Every second counts. The person responsible for overall
safety and design must verify that the total time for the analyzer to respond plus the time needed for
effective corrective action is less than the time it takes for any foreseeable upset condition to produce
an explosive concentration.
WARNING! An extremely rapid rise may reach 100% LFL before the analyzer can make an alarm.
PrevEx®InstructionManual
19
THEORY OF OPERATION
2.8.4.
Fuel Pressure Limits
The sensing flame needs constant fuel pressure to operate. Low pressure causes downscale reading
drift. Loss of pressure extinguishes the sensing flame. Keep the entire fuel line clean and free of
leaks. Maintain fuel pressure above the minimum. In cases where the analyzer is used to control
processes, a pressure switch that monitors the fuel line for a loss of pressure is required.
WARNING!
2.8.5.
Low fuel pressure can cause false low readings. Always maintain proper fuel pressure.
Flash Point Limitations
Flammable gases and vapors with Flash Points above the operating temperature of the sensor and
sampling system will condense before they can be measured. This can result in false low readings,
failure to detect a flammable or explosive concentration, or clogging in the sampling system.
WARNING!
The analyzer cannot detect flammable vapors with Flash Points above the operating
temperature of the analyzer or any portion of the sampling system. DO NOT ATTEMPT
TO MONITOR A FLAMMABLE VAPOR WITH A FLASH POINT ABOVE THE
ANALYZER‘S OPERATING TEMPERATURE.
Some industrial processes can use a variety of solvents having different flash points. Each solvent to
be monitored must have a flash point below the analyzer and sampling system operating
temperatures. Before a new solvent is used, the flash point must be checked.
WARNING!
2.8.6.
The SNR671 analyzer cannot detect flammable vapors with Flash Points above 60ºC.
Condensation Limits
Hot vapors condense when cooled below the dew point. The dew point of water and other nonflammable vapors in the sample should be lower than the entire sampling system. Condensation can
result in flow system fouling, erratic flow, and other sampling problems. The combination of
condensing water and water-soluble solvents might cause false low readings.
WARNING!
2.8.7.
Condensation of flammable vapors in the sampling system may delay or disable alarms.
Ambient Temperature Effects
The analyzer reading drifts a small amount from ambient temperature changes. This error can be
removed by recalibration. Recalibrate if the ambient temperature changes more than 50C. Removal
of the analyzer cover can also cause small errors. Calibrate by remote controls to prevent this error.
2.8.8.
Flow Effects
Changes to the sample flow rate can affect accuracy, especially for air dilution types. During
calibration, the flow rate must be observed to verify that it matches the flow rate during sampling,
and the LOW FLOW setting should be set within 0.4 LPM of the flow rate during calibration.
2.8.9.
Sample Pressure Effects
When sampling from a process at increased or decreased pressures, a small amount of error is
created. This error can be removed by recalibrating. The use of a pressure regulator in the sample
line is not recommended. During calibration, excess calibration gases must flow freely out the
sample inlet. A pressure regulator in the sample line can interfere with the flow of calibration gases
and reduce accuracy or cause faults.
20
Control Instruments Corp.
THEORY OF OPERATION
2.8.10.
Halogens
Halogens and halogen-containing substances such as chlorine, fluorine, bromine, hydrogen chloride,
trichloroethylene, dichlororethylene, vinyl chloride, and freons will produce halogen acids when
oxidized in the sensing flame. The analyzer is constructed of stainless steel and hard coated
aluminum components with corrosion resistance. Under normal conditions, these substances do not
affect performance. Some halogenated hydrocarbons that are relatively non-flammable in air produce
a flammability reading at very high concentrations. Some mixtures of halogens and amines may form
ammonium chloride upon contact with the heated analyzer. The process chemistry must be taken into
account to ensure that a representative sample reaches the analyzer‘s flame cell. For example,
halogens in the presence of amines can form solids upon contact with a hot analyzer.
2.8.11.
Combustible Dusts, Aerosols and Mists
This analyzer cannot measure combustible dusts, aerosols and mists, which can form explosive
mixtures in air, but are not in the vapor state, and may be trapped in the sample filter.
WARNING!
2.8.12.
The analyzer does not provide protection from the fire and explosion hazards of
combustible dusts, aerosols and mists.
Silicones
Performance is generally unaffected by silicones. Extremely high silicone concentrations require
extra maintenance to remove silicone dust on the burner and exhaust filter. An optional flow system
that reduces silicone effects is available. Contact Control Instruments for recommendations in
handling samples with extremely high silicone content.
2.8.13.
Autoignition / Decomposition Temperature
Substances which auto ignite or decompose at or below the analyzer operating temperature will not
be detected. For example, Carbon Disulfide (CS2) has an approximate autoignition temperature of
90C, and so will not be detected in an analyzer operated above that temperature.
WARNING!
2.8.14.
The analyzer cannot measure substances that thermally or chemically decompose from
contact with the heated sampling system.
Analyzers used for control
If the analyzer signal controls a process, for example to vary process speed or ventilation rate, or to
modulate some process control device, a ―secondary safety‖ must ensure that analyzer faults cannot
cause an unsafe condition. Industry standards, for example ―Safety Instrumented Systems‖ require
safety devices to be independent of process control. Otherwise, a fault in the analyzer that produces
false low readings could cause an unsafe condition in the process (reduced ventilation, increased
speed, etc.) without warning or alarm.
WARNING!
Analyzers used for process control purposes require a secondary means of safety. A
redundant analyzer, or an independent physical limit on the flammable gas concentration,
must be used.
Low fuel pressure can cause false low readings. Analyzers that control a process require the correct
fuel pressure at all times. If the fuel pressure is below the minimum the controls must be forced to a
safe state.
WARNING!
Analyzers used for control purposes require continuous monitoring of fuel pressure, and
an automatic alarm that performs a safety shutdown when the fuel is below the minimum.
PrevEx®InstructionManual
21
SPECIFICATIONS
3.
Specifications
Measurement range
0 to 100% LFL display range. 0 to 80% LFL range for stated
accuracy. Display blinks when reading exceeds 80% LFL to indicate
readings outside of accuracy range.
Flame Cell Temperature
SNR671: 60°C
SNR672: 120°C
SNR674: 200°C
SNR675: 250°C
Accuracy
± 3% of full scale, or 10% of applied gas concentration, whichever
is greater12
Repeatability
± 1% of measurement range
Zero Stability
± 1% in 30 days
Span Stability
± 5% per year
Response Time
As tested and approved:
Factory Mutual/FMc
CENELEC/ATEX
T90 less then 1 second to 90% of final
Dilution TYPEs ―D‖ & ―K‖
All other types
T50 T90
T50
HSG
HSG
reading, plus sample transport of 1 second.
[s]
[s]
[s]
TEMP
SPEED
TEMP
SPEED
One second for every 6 feet of ¼ inch OD
[
ºC
]
[
ºC
]
additional sample tubing, if used.
Sample Transport Time
Stabilization Time
Sample Pressure Effect
100
270
3,0
3,0
3,8
3,8
60
60
LOW
LOW
MED
2,6
2,3
3,6
3,1
270
MED
2,7
3,3
60
HIGH
2,0
3,0
270
HIGH
2,3
3,0
200
LOW
2,2
2,6
OFF
10,5
29,0
200
200
MED
270
HIGH
2,0
1,7
2,4
2,1
MED
0.5 seconds per meter of ¼ inch OD tubing.
1.0 second per meter for air dilution option.
Calibration gas should be applied for at least 60 seconds
Increase in pressure decreases the reading slightly. Air dilution
types (D, K) have twice as much sample pressure effect.
Factory Mutual/FMc
CENELEC/ATEX
TYPE
%LFL per inch of water
%LFL per millibar
Air Dilution
Types D,K
SNR671
SNR672
SNR674
SNR675
12
-0.20
-0.14
-0.10
-0.10
-0.08
-0.06
-0.04
-0.04
-0.16
-0.12
-0.08
-0.08
Air dilution types (D and K) are accurate in the range from 0 to 60% LFL.
PrevEx®InstructionManual
T90
[s]
22
SPECIFICATIONS
Sample Pressure Limit
Ambient Temperature Range
Sample Flow Rate
Sample Flow Rate Effect
Sample Flow Rate Limit
Calibration Test Gas
Calibration Gas Pressure
Calibration Gas Consumption
Calibration Hardware Kit
CENELEC Accuracy limit. Maximum deviation in pressure relative
to nominal (point of calibration):
+/- Pressure change from calibration
TYPE
Standard Types
Air Dilution Types D, K
SNR671
50hPa
25hPa
SNR672
67 hPa
33hPa
SNR674
100 hPa
50hPa
SNR675
100 hPa
50hPa
As tested and approved:
Model#
Factory Mutual
FMc
CENELEC/ATEX
SNR671 –25°C to 60°C
0°C to 40°C
–10°C to 60°C
SNR672 –25°C to 65°C
0°C to 40°C
–10°C to 60°C
SNR674 –25°C to 65°C
0°C to 40°C
–20°C to 60°C
SNR675 –25°C to 65°C
0°C to 40°C
–20°C to 55°C
LCD Visibility Range: –20°C to 45°C ambient range
Extended range, factory specification, not tested nor approved:
Model#
Range
SNR672
–40°C to 65°C
SNR674
–40°C to 65°C
Recommended range of operation, factory specification
Model#
Range
SNR671
0°C to 50°C (indoor)
SNR675
0°C to 50°C (indoor)
Range for stated accuracy is 50°C, or within +/-25°C of temperature
at which calibration was performed.
Typical range: 2.5 0.5 liters per minute13
Low Flow:
Less than 1.4 liters per minute
The reading increases approximately 1% LFL for a 0.1 liter per
minute decrease in the sample flow rate.
CENELEC accuracy limit - maximum deviation relative to nominal
(point of calibration) 0.4 liters per minute change in flow rate. The
LOW FLOW setting should therefore be set within 0.4 LPM of the
flow rate during calibration. For air dilution types (D, K) this limit
is 0.2 LPM.
1.15% by volume Ethylene in air or 0.91% Propane in air.
Tolerance should be within +/-2% of specified concentration.
20 PSIG (1.4 bar) inlet pressure
Approximately 7 SCFH (3.5 liters per minute) during calibration
Part# PRV022 set to 20 PSIG delivery pressure at span inlet
13
Air dilution units draw less than half their total flow rate from the sample - the ―sample‖ flow is half that
indicated by the ―FLOW ‖ register. The balance of flow into the flame cell is dilution air.
PrevEx®InstructionManual
23
SPECIFICATIONS
Oxygen Limitation
Oxygen Effect
Dimensions
Storage Temperature Range
Ambient Humidity
Ambient Pressure Range
Dew Point / Flash Point
Fuel Required
Fuel Pressure Limit
Sample Inlet
Exhaust Outlet
Compressed Air
Fuel Inlet Connection
Span Gas Inlet
Electrical Connections
24
0 to 21% oxygen with air dilution option and hydrogen fuel
12 to 21% oxygen with hydrogen fuel
19 to 21% oxygen with propane fuel
Using hydrogen fuel, the reading increases 1% LFL for each one
percent (1%) decrease in oxygen concentration. The effect for
propane fuel is approximately three times higher.
For air dilution types the reading increases 0.7% LFL for each 1%
decrease in oxygen concentration.
16"H x 12.1"W x 8.5"D (41cm H x 31cm W x 22cm D)
As tested and approved:
Model#
Factory Mutual
FMc
CENELEC/ATEX
SNR671
–40°C to 65°C -40°C to 65°C
–40°C to 60°C
0 to 100% Relative Humidity (non-condensing)
800 to 1100 hPa (millibar). Air dilution types are within stated
accuracy when pressure range is within +/- 50 hPa of the ambient
pressure at the time of calibration; All other types are within stated
accuracy when pressure range is within +/- 100 hPa of the ambient
pressure at the time of calibration.
Must not exceed lowest temperature found in any part of sampling
system and flame cell. To reach maximum Flash Point requires
increase of HSG TEMP setting and recalibration.
Type
Factory Setting Maximum
SNR671
60°C
60C
SNR672
120°C
153°C
SNR674
200°C
210°C
SNR675
250°C
280C
Fuel Type:
Hydrogen, prepurified 99.99% minimum
Inlet pressure: 40 to 45 PSIG (2.7 to 3.1 bar)
Consumption: 58 Liters per day
or
Fuel Type:
Propane, 99% minimum purity
Inlet pressure: 30 to 35 PSIG (2.0 to 2.4 bar)
Consumption: 1 Pound per month
CENELEC hydrogen fuel pressure limit 3.1 bar.
1/4" outside diameter (OD) tubing standard, except 3/8" OD for
HTR075 concentric probe and MTG058 dual tube mounting.
3/8" OD tubing for wall mount (MTG053) and dual tube (MTG054,
MTG058) types, 3/4‖ OD for concentric sample probes (HTR063,
HTR075)
3/8" OD tubing or larger for main lines. Reduce to 1/4" OD tube
connection at analyzer inlet.
Requires 1/4" OD tubing
Requires 1/4" OD tubing
Two 3/4 " NPT (pipe), for independent AC and DC connections
Control Instruments Corp.
SPECIFICATIONS
Compressed Air Required
Electrical Power Required
Warm Up Time
Materials
Hazardous location Rating
NEMA Rating
4-20mA Output
Milliamp Output Range
Inlet pressure: 20 1 PSIG (140 kPa), regulated
Consumption: 42 SCFH, 21 Liters per minute
Quality:
Per ANSI/ISA-7.0.01-1996 or equal
Must be clean, dry, and oil-free.
Dew Point:
At least 10°C below ambient
Particulate:
Less than 40 micrometer
Lubricant:
Less than 1 part per million
Voltage:
Either 120 VAC or 230 VAC
Factory built to accept only one range.
Must use rated sensor voltage
Tolerance:
+10%, -15% of rated voltage
Frequency:
50 to 60 Hertz
Power:
400 Watts maximum
30 to 90 minutes varying with sensor type and ambient conditions.
Stainless Steel (300 series) and corrosion-resistant, hard-coat
aluminum. Brass fittings on SNR671.
See section 1.4. Refer to serial plate for rating and approval marks.
NEMA 12 (HSG228) standard, NEMA 4X (HSG229) optional
Self-powered, non-isolated output signal. Delivers 4mA at 0%LFL,
20ma full-scale to a passive load. Maximum load resistance is 275
Ohms total, which allows 250 Ohms non-inductive load plus 25
Ohms line resistance.
4 to 20 milliamps for 0 to 100% LFL, full range 2.5 to 22.7
milliamps.
Milliamp Output Notice
In order to signal a special state such as faults or the flooded
condition, the MA FAULT and MA CAL settings should be configured
outside the normal range of the milliamp output.
Rate of rise notice
This function is outside the scope of CENELEC norms and was not
examined during ATEX approval testing.
For special state ―Flooded,‖ refer to ―Flameout from Flammable
Mixtures - Flooded‖ under ―Theory of Operation.‖
60 Watts (VA) non-inductive
0.5 Amp at 125 VAC
0.2 Amp at 230 VAC
2.0 Amp at 30 VDC
O-ring storage is five to ten years under clean, dry conditions.
For best results: Temperature 0°C to 50°C, and Humidity 10 to 90
%RH. Avoid strong light, direct sunlight, ozone and oxidizers. Use
sealed polyethylene bags.
35 to 40 lbs. (16 to 18 kg.) - Depending on options
Frequency less than 25 Hz with amplitude less than 0.15mm
Install upright only: less than 15º deviation from vertical.
0º degrees is preferred. CENELEC accuracy limit allows maximum
deviation 2.5° relative to nominal (point of calibration).
Special state notice
Relay rating
O-Ring Storage
Weight
Vibration
Orientation
PrevEx®InstructionManual
25
INSTALLATION
4.
Installation
WARNING!
The accuracy and reliability of the analyzer depends completely on proper installation.
4.1.
Unpacking
Check the packing list and contents of the shipment. Look for additional components: mounting
gaskets, regulators, and sample probes. Retain shipping materials through installation and startup.
4.2.
Equipment, materials, and utilities
AC electrical power, at 400 Watts (VA) maximum per analyzer, at a voltage matching the serial
plate. The analyzer is factory-set for either 120 VAC or 230 VAC, but not both.
Fuel gas cylinder or generator, and pressure regulator. The analyzer is factory-set for only one
fuel type, either hydrogen or propane, but not both. Pressure at the fuel inlet must match the pressure
rating on the serial plate. Hydrogen is typically 45 PSIG (310 kPa), propane 35 PSIG (240 kPa).
Calibration span gas cylinder and pressure regulator, typically 1.15% Ethylene in Air with 20 1
PSIG (140 kPa) delivery pressure at the span inlet.
Calibration zero gas cylinder or compressor, and pressure regulator for clean, dry compressed
air with 20 1 PSIG (140 kPa) delivery pressure at the zero inlet. If a compressor is used in place of
the zero gas cylinder, include a shutoff valve.
Clean, dry, regulated compressed air. Delivery pressure to the air inlet is 20 ± 1 PSIG (140 kPa).
A properly sized air filter and regulator must be used.
Either Stainless steel sample and exhaust tubing or Sample probe. Optional sample probes or
sample tubes may be supplied with the analyzer. Otherwise, use ¼ inch OD stainless steel tubing for
the sample and 3/8 inch for the exhaust.
Copper or stainless steel tubing for utilities, for connecting the fuel, air and calibration gases.
Shutoff valves for fuel, air and calibration gases, so that the sensor can be disconnected for
service or maintenance procedures without affecting other equipment using the same utilities.
Switch for AC power, so that analyzer can be serviced safely.
Mounting bolts, washers and nuts. Size 3/8 inch mounting bolts or their metric equivalent.
Either Conduit seals or cable glands, to seal electrical connections at the enclosure entrance.
Mounting supports, saddles and/or flanges as needed, depending on the particular application.
Mount analyzer upright, at zero degrees around X and Z-axis.
Size AWG 14 wire (1,3mm to 1,6mm diameter) for AC power, or the metric equivalent.
Size AWG 14 to AWG 24 wire (0,5mm to 1,6mm diameters) for relays and outputs. The terminals
accept these wire gauges. The wire size depends on the relay or output function and current-carrying
capacities of the circuit. Stranded wire is preferred.
Size AWG 22 (0,6mm dia.) shielded three-conductor wire for RS 485 serial communications.
Tools required: Tube fittings are fractional inches: 9/16 inch, etc. Flame cell bolts are metric.
Purge and pressurization system. The analyzer is rated by Factory Mutual Research for Class I,
Division 2, Groups A, B, C & D. Use of an optional TYPE Y AIR PURGE improves the rating to Class I,
Division 1, Groups A, B, C & D hazardous areas. The flame cell is always rated for sampling from
Division 1 or Zone 1 hazardous areas. The rating must meet or exceed the hazardous area rating
requirements for its location.
26
Control Instruments Corp.
INSTALLATION
4.3.
Location and Mounting
Obtain a representative sample. Position the probe for a reliable and accurate sample. This
requires an understanding of the behavior of the gases and vapors being monitored, and the process
itself. Consider the effects of fans and dampers in normal and upset conditions.
Install as close as possible. For good sampling and a fast response, the sample and exhaust tubes
must be short.
Keep sensor upright. Do not tilt more than 15° from the vertical axis (at 0° about the X and Z axes).
Maintain the hazardous location rating. Install in an area suitable for the analyzer‘s rating.
Avoid Pressure Spikes. Keep away from fans, dampers, tees and elbows. For best performance,
position the probe where the duct pressure remains near atmospheric pressure.
Provide access for service. Allow for safe and effective routine maintenance. Keep clearance space
around the analyzer. If necessary, catwalks, railings or ladders may be required.
Ensure easy probe removal for cleaning. The sample and exhaust lines must be removable for
periodic cleaning, especially in processes having high levels of particulate. If a pipe is installed
between the oven's or duct‘s inner and outer walls, this pipe should be large enough to allow
installation of the sample and exhaust lines, including all bends in those lines.
Insulate duct-mounted sensors using a gasket. The gasket allows mounting on surfaces up to 75°C.
The sensor can sample from process ducts having much higher interior temperatures, limited mainly
by the materials of the sample probe.
Seal duct entry holes. Prevent leaks that cause cooling or dilution of the sample, or allow process
gases to leak into the analyzer housing. If used, fully weld flanges or mounting saddles.
Use inlet restrictor fittings. The fuel inlet fitting, and zero and span inlet fittings, contain sintered
metal restrictors to control flow rates. These must be used to make the tubing connections. They can
only be replaced with identical restrictor fittings.
Remove the shipping bracket. Some shipment methods use a steel bracket to support the flame cell
in transit. The bracket is tagged, indicating that it must be removed before the analyzer is operated.
4.4.
Sample and Exhaust Tubing
Use suitable materials. Stainless steel is the minimum material for the sample and exhaust tubes.
High temperature processes may require other materials. Copper is generally unacceptable.
Keep tubes short. Short tubes give the fastest response and require the least maintenance. Long
tubes can greatly delay the sensor response and affect the safety of the gas alarm system. Sample
transport time is approximately 6 feet (2 meters) per seconds through standard ¼ inch tubing.
Keep sample-tubing volumes low. Filters and large diameter tubes cause sampling delays. Use ¼
inch 0.035 inch wall thickness tubing. Do not add bowl filters to the sample line.
Keep tubes hot. Prevent condensation and clogging. Never expose sample or exhaust tubing to room
temperature, even for a very short distance. All tubes must be kept above the dew point(s) and flash
point(s). If the sensor is not mounted directly on the process duct, the sample and exhaust tubes must
be heat-traced to a temperature above the flash point(s) and dew point(s) of all substances in the
sample stream. In cases where duct mounting is not possible, please contact Control Instruments
Corporation for guidance in heat-tracing sample and exhaust lines.
Avoid short radius bends. This can cause clogging and make service difficult.
Keep tube openings perpendicular to the duct flow. Prevent sampling problems from a pitot
effect. Do not aim the sample or exhaust tube openings directly into the process flow.
PrevEx®InstructionManual
27
INSTALLATION
Position the sample probe properly, near the center of the duct where it can obtain a representative
sample. Profiling of the duct might be necessary.
Position exhaust tube correctly. The exhaust should be at the same duct pressure as the sample,
positioned where it cannot dilute the sample.
Install tube at or below the horizontal. If some condensation of water vapors is unavoidable, the
sample and exhaust tubes must slope downward to carry condensate away from the analyzer. Sample
tube diameter of 3/8 inch may be needed to avoid plugging by water droplets.
Keep lines leak-tight. Avoid unnecessary joints or couplings. Leaks cause false low readings.
Provide access for service. Cleaning or replacement may be required. If necessary, install a tube
union to allow removal of the tubes.
Seal duct openings. Access holes in the duct wall must be sealed to prevent leaks that might dilute
the sample, or cool the sample tubing and cause condensation.
Tube installation/removal. There are several mounting options:
Type
Dual tube
Concentric
Wall mount
4.4.1.
Reference part #
MTG054 or MTG058
HTR063 or HTR075
MTG053
Description
Duct mount, dual tube
Duct mount, concentric probe
Wall mount, dual tube
Section
4.4.1
4.4.2
4.4.3
Dual Tube Duct Mount
Reference part numbers MTG054 and MTG058
The sample tube and exhaust tube each pass through their respective bulkhead fittings. The exhaust
tube is cut to a length that just penetrates the duct. The sample tube is cut to positions it at the center
of the duct. For MTG054, the sample tubing is ¼ inch OD, for MTG058 it is 3/8 inch OD. All parts
of the sample tube must be protected from exposure to cold surfaces or cold air. The analyzer is
sealed and insulated with a gasket. The entry into the duct must also be sealed so that a cold spot
does not form when room air enters the duct opening adjacent to the probe.
If the maximum temperature inside the duct exceeds 250°C, insulation must be packed into the space
between the rear of the analyzer and the inside wall of the duct, as shown.
28
Control Instruments Corp.
INSTALLATION
4.4.2.
Concentric Sample Probe
Reference part number HTR063 or HTR075
The exhaust tube surrounds the sample tube to protect it from heat losses. The exhaust is cut to
length and de-burred. It just penetrates the duct. The sample is positioned to obtain a representative
sample, usually at the center of the duct. If possible, the analyzer is mounted flush to the duct
surface, using a gasket to seal and insulate.
For the standard probe, part number HTR063, the sample tubing is ¼ inch OD. An optional probe,
part number HTR075 is similar, except the sample tubing is 3/8 inch OD. HTR075 is useful where
condense water vapors might occasionally form from mists in the duct. Its larger sample tubing
diameter is not easily obstructed by a water droplet.
A
C
B
D
When the duct surface is above 75ºC, or if the duct is circular, the analyzer is not flush with the
surface of the duct. The analyzer should be one or two inches (3 to 5 cm) from the duct. The
concentric probe is insulated so that no part is exposed. The entry into the duct is sealed so a cold
spot does not form at the duct opening adjacent to the probe.
PrevEx®InstructionManual
29
INSTALLATION
4.4.3.
Calibration Injection Methods
The standard method of injecting calibration gas directly opposite the incoming sample stream,
shown at left, below, helps detect leaks in the flame cell. Applications with high levels of
contaminants use the block injection method, below right, to protect the calibration tube nozzle.
Calibration Probe Injection
Calibration Block Injection
Sample and Exhaust Probe
Assembly - Dual Tube or
Concentric Types
Sample
Inlet
Sample and Exhaust Probe
Assembly - Dual Tube or
Concentric Types
Exhaust
Outlet
Sample
Inlet
Calibration
Inlet
Calibration
Inlet
For Block Injection: Calibration
inlet is at the front of the block.
For Probe Injection: Sample and
Calibration inlets are on opposite
sides of a "Tee" fitting.
Probe injection helps detect leaks.
Calibration tube delivers gas to
center of "Tee."
4.4.4.
Exhaust
Outlet
Use block injection with 3/8 inch
OD Sample probe, or when sample
stream has high levels of
contaminants.
Calibration
Tube
Part# TUB093
Calibration
Tube
Part #TUB083
Wall Mount
Reference part number MTG053. Both the ¼ inch OD sample tube and 3/8 inch OD exhaust tube
connect to fittings on the sidewall of the analyzer. The sample tube is positioned to obtain a
representative sample and is cut to length and deburred. The exhaust tube is positioned at a point in
the duct slightly downstream and/or at a distance from the sample inlet, so that the exhaust cannot
dilute the sample. Cut tubes to length and debur.
FAULT
30
DANGER WARNING
HORN
ZERO
SPAN
IGNITE
HEAT
Control Instruments Corp.
INSTALLATION
4.4.5.
Mounting Dimensions
Use four mounting bolts. For the optional Wall Mount SNR671 type (MTG053) sample and exhaust
tubes connect to the side of the analyzer. For all others, sample probes connect through the rear of
the analyzer‘s upper right corner. Leave 6 to 10 inches (15 to 25 cm) clearance on all sides. Some
analyzers need room for a purge/pressurization system at the upper left.
10.50 [266.7]
Ø0.44 [11.12]
12.65 [321.4]
5.25 [133.3]
12.10 [307.4]
2.98 [75.6]
2.58 [65.5]
15.77
15.94 [404.8]
15.00 [400.6]
[381.0]
C
L
FRONT VIEW OF ANALYZER
REAR VIEW OF ANALYZER
5.75 [146.0]
11.50 [292.1]
10.50 [266.7]
5.25 [133.3]
2.98 [75.6]
8.26 [210]
2.58 [65.5]
PROBE HOLE, DIAMETER 1.OO [25.4]
PROBE ASSEMBLY IS 0.750 [19.1] OUTER DIAMETER.
IT PASSES THROUGH A SEAL FITTING AND BRACKET THAT HAS
A OUTER DIAMETER OF 0.875 [22.2]. THE PROBE SEAL BRACKET
CAN BE ADJUSTED SLIGHTLY TO ALLOW FOR TOLERANCES.
15.00
[381.0]
SIDE VIEW
[400.6]
DIMENSIONS ARE INCHES [MILLIMETERS]
5.25 [133.3]
THE ANALYZER HAS FOUR MOUNTING HOLES.
THE TWO LOWER MOUNTING HOLES ARE SLOTTED.
THE MOUNTING HOLES ARE 0.44 [11.12] DIAMETER.
MOUNTING HOLE, 1 OF 4
10.50 [26.67]
PrevEx®InstructionManual
1.17 [29.7]
31
INSTALLATION
4.5.
Utilities
Electrical power, fuel and compressed air must be supplied continuously without interruption.
Turning off the analyzer at night or on weekends can result in startup delays and operating problems.
Compressed air is used to prevent an accumulation of fuel within the enclosure in case of a leak. If
compressed air is temporarily unavailable, turn off the fuel supply as a precaution.
Sampling into an unheated sensor can result in condensation and clogging. During installation, keep
sample and exhaust tubing disconnected until startup. If the analyzer is to be left unheated for some
time, and if the process being monitored contains substances that might condense when cooled, then
the analyzer should be locked out and the sample and exhaust tubing should be disconnected.
Compressed air supply
Use clean, dry compressed air. The analyzer requires clean, dry ―instrument grade14‖ compressed
air that is free of oil and water. Water or oil in the air source can cause damage or affect accuracy.
Filter and regulate the compressed air. Install an external air pressure regulator and filter. Set the
pressure on this regulator to 20 PSIG (1,4 bar). Allow for a maximum air consumption rate of 1
standard cubic foot per minute (28 liters per minute) for each analyzer.
Use 3/8” OD copper tubing or better. Refer to flow diagrams for correct tubing diameters, lengths
and quantity of analyzers.
Install a manual “shut off” valve near the Compressed Air inlet, to simplify service and
maintenance routines. Use ¼‖ OD copper tubing to connect the ―shut off‖ valve to the air inlet.
Keep the compressed air dew point well below the coldest expected temperature. Failure to do
so may result in frozen compressed air lines. Outdoor compressed air lines require special care.
Protect inerted processes from air in the exhaust. The analyzer‘s exhaust contains compressed air
and dilution air. 100% nitrogen may be used as the compressed ―air‖ source, but the dilution must
still use air. Make certain that this volume of air will not adversely affect an inerted process, or take
special precautions to plan an alternate exhaust method.
Connect the compressed air to the (optional) air dilution inlet. If this factory-installed option is
used, it requires 20 PSIG (140 kPa) at the dilution air inlet.
4.6.
Air Filter Assembly
Part #FLT070
INLET 1/4 NPT FEMALE
Maximum working pressure 150 PSIG (10 bar)
Maximum temperature 125°F (52°C)
Suitable for up to 18 analyzers
Maximum flow rate 14 SCFM (400 LPM)
Assembly exceed ISO Class 1 for particulate size,
solid contaminates and oil content.
PARTICULATE
FILTER
1
OUTLET 3/8" TUBE CONNECTION
2
COALESCING
Dimensions: 7.8 x 7.8 x 3.5 inches
200 x 200 x 90 mm
Weight:
3.6 lb
1.6 kg
COALESCING
FILTER
BLOCK DIAGRAM
14
Refer to ISA-7.0.01-1996 for specifications of instrument grade air.
32
Control Instruments Corp.
INSTALLATION
CONTROL INSTRUMENTS - PREVEX FLAMMABILITY ANALYZER - EXTERNAL FLOW SCHEMATIC
BASIC UTILITIES (AIR, FUEL, CALIBRATION GAS)
Connections for air purge, sample and exhaust are not shown.
A
FUEL
K
FUEL TYPE AND PRESSURE MUST MATCH NAMEPLATE
K
FUEL PRESSURE MUST BE KEPT WITHIN INDICATED RANGE
FUEL INLET FITTING HAS SINTERED METAL FILTER INSIDE
DO NOT REMOVE FUEL INLET FITTING
TURN OFF FUEL PRESSURE WHENEVER AIR PRESSURE IF OFF
B
AIR DILUTION - FACTORY INSTALLED OPTION
PREVEX ANALYZER - FRONT VIEW
CONNECT TO 20 PSIG (1.4 BAR) INSTRUMENT AIR
PREVEX ANALYZER - FRONT VIEW
C F K AIR PURGE / PRESSURIZATION CONNECTIONS
CONNECTIONS DEPEND ON ANALYZER TYPE
AND HAZARDOUS RATING.
D SPAN CALIBRATION GAS
TURN OFF PRESSURE WHEN NOT IN USE
E ZERO CALIBRATION GAS
TURN OFF PRESSURE WHEN NOT IN USE
G INSTRUMENT AIR
CLEAN, DRY AND OIL-FREE
INLETS ARE 1/4 INCH OD TUBE COMPRESSION FITTINGS.
TUBING IS 1/4 INCH OD, EXCEPT AIR LINE MAINS
B
A
C
D
E F G
A
B
C
D
E F G
INLET PRESSURES ARE 20 PSIG (1.4 BAR) EXCEPT FUEL
INLET PRESSURE TOLERANCES ARE 5%, EXCEPT FUEL
INLETS A, D AND E HAVE SINTERED METAL ORIFICE ELEMENTS INSIDE
REPLACE ONLY WITH IDENTICAL PART NUMBER
INSTRUMENT AIR TUBING IS 3/8 INCH OD OR LARGER
PRESSURE INDICATING GAUGE OR TEST PORT AT END OF LINE
SET SUPPLY PRESSURE TO MAINTAIN MINIMUM AT END OF LINE
FUEL
SHUTOFF
VALVE
AIR
SHUTOFF
VALVE
FUEL
SHUTOFF
VALVE
AIR
SHUTOFF
VALVE
FUEL
"HYDROGEN"
"PROPANE"
40 TO 45 PSIG 30 TO 35 PSIG
2.8 TO 3.1 BAR 2.0 TO 2.4 BAR
SEE
NOTE
SPAN CALIBRATION GAS
20 PSIG
1.4 BAR
ZERO CALIBRATION GAS
INSTRUMENT AIR
MAXIMUM LENGTH OF COMPRESSED AIR SUPPLY LINE
20 PSIG
USING 3/8 INCH OD TUBING:
1.4 BAR
FOR 16 ANALYZERS, 200 FEET (60 METERS)
8 ANALYZERS, 400 FEET (120 METERS)
CALIBRATION GAS
4 ANALYZERS, 800 FEET (240 METERS)
SHUTOFF VALVES
MAXIMUM LENGTH IS DOUBLED FOR 1/2 INCH OD TUBING,
OR AIR PRESSURE AT 80 PSIG (6.9 BAR)
TURN OFF CALIBRATION GAS
WHEN NOT IN USE.
COMPRESSED AIR
SUPPLY LINE
50 PSIG
3.4 BAR
PARTICULATE
FILTER
COALESCING PRESSURE
REDUCING
FILTER
VALVE
INSTRUMENT AIR
20 PSIG
1.4 BAR
MAXIMUM LENGTH OF INSTRUMENT AIR MAIN USING 3/8 INCH OD TUBING:
FOR 8 ANALYZERS, 50 FEET (15 METERS)
5 ANALYZERS, 80 FEET (25 METERS)
2 ANALYZERS, 200 FEET (60 METERS)
MAXIMUM LENGTH IS DOUBLED BY USING 1/2 INCH OD TUBING.
Typical installation of pneumatic utilities for a PrevEx analyzer.
PrevEx®InstructionManual
33
INSTALLATION
4.7.
Fuel supply cylinders
Observe precautions and regulations for safe storage and handling. The fuel supply system
should conform to all applicable codes15.
Use only the specified fuel. The sensor is factory built to accept only one type of fuel.
Use inlet restrictor fittings. The fuel inlet requires a special fitting with a factory-installed
restrictor. Do not remove or replace this fitting. It is necessary for controlling the flow of fuel.
Separate fuel cylinders from calibration cylinders. Calibration cylinders are equivalent to
compressed air and should be separated from fuel cylinders by a safe distance or rated barrier.
Install warning sign and post operating instructions.
Use an approved cylinder rack or mounting system.
Install a pressure relief device vented to a safe outdoor location.
Limit the number of sensors on a common fuel line, to allow use of a safer excess flow limit.
Install an excess flow valve or flow restrictor. Allow a flow rate of at least 50 cubic centimeters
per minute per analyzer for hydrogen fuel, and 10 cc/min per analyzer for propane fuel.
Install a low-pressure switch and alarm. Low fuel pressure causes false low readings. Especially
for process control, monitor the fuel line with a pressure switch that alarms if the pressure falls
below the minimum.
Install a flexible tubing loop at the cylinder, to facilitate cylinder changes.
Use ¼ inch OD stainless steel or copper tubing. Do not use flexible tubing. Keep tubing clean to
prevent contamination. Do not use flux and solder, black pipe and pipe dope, or sealant. Use leak
check solutions only on the outside of the tubing. Fuel flow and pressure drops are insignificant as
long as leaks are prevented. ¼ inch OD tubing is the correct size. Do not use large diameter fuel
lines or headers.
Use compression fittings. Soldered or threaded connections that use flux or sealant will contaminate
the fuel line, and cause reading drift or clogging of the fuel inlet restrictor. Fuel purity is important.
Install a shutoff valve at the fuel inlet for use during maintenance.
Test fuel lines for leaks. Eliminate all fuel line leaks.
Set the fuel regulator at the cylinder to deliver the correct pressure. Do not over- or underpressurize the fuel line.
Set backup cylinder pressure lower than the primary. For systems with two cylinders, the
pressure of the primary regulator should be slightly higher than the secondary regulator. In this way,
fuel is drawn from the primary cylinder until it is nearly empty. Then the pressure drops slightly to
the pressure of the secondary cylinder. This gives an indication that the primary cylinder is empty
and needs replacement.
Wait for fuel lines to purge before startup. It may be necessary to wait one hour or more for fuel
lines to purge themselves of trapped air. The reading drifts slowly upscale until all air is removed.
15
For example, in the USA, these may include: 29CFR chapter XVII, Paragraphs 1910.101(b) and
1910.103(a)(2)(i)(b) Hydrogen Systems less than 400 cubic feet, Compressed Gas Association, Pamphlet CGA
P-1-1984 Safe Handling of Compressed Gases in Containers, or National Fire Protection Association - NFPA
50A Standard for Gaseous Hydrogen Systems at Consumer Sites - Safe Handling of Compressed Gases in
Containers.
34
Control Instruments Corp.
INSTALLATION
4.8.
Zero and Span Test Gases
Use inlet restrictor fittings supplied with analyzer. The zero and span inlet fittings contain
sintered metal restrictors that control the calibration flow rate. Do not remove these fittings. Do not
replace them with other fitting types.
Supply “Zero Air” at 20 PSIG (140 kPa) to the zero inlet during calibration. If the compressed air
supply is used for zero air, it must be clean, dry, oil-free, and regulated to 20 PSIG.
Supply “Span Gas,” 1.15% Ethylene in Air, at 20 PSIG (140 kPa) to the span inlet during
calibration. Cylinder part number CYL018 or equal. See calibration instructions for requirements.
Shut zero and span gas off at the cylinder valve when not in use. This prevents loss of gas from
minor leaks, and prevents unintentional or accidental injection of test gases. When compressed air is
used in place of a zero gas cylinder, provide a zero gas shutoff valve, to turn off air pressure to the
zero inlet when not in use.
4.9.
AC Power
Observe proper precautions for handling AC power. Do not open covers when circuits are live.
Allow 400 Watts (VA) per sensor peak power. Average power consumption is lower.
Supply correct voltage. Voltage is factory configured to either 120VAC or 230VAC—but NOT
BOTH. Input voltage is marked on the serial plate on the side of the analyzer.
Supply power continuously. Electric heaters stabilize readings and prevent condensation. Loss of
power can cause condensation that requires cleaning before the analyzer can be put into use.
Supply multiple analyzers from same main circuit. Prevent ground loops and electrical problems
by properly grounding all analyzers at the same point. This is required for serial communications.
Use proper grounding. Connect the AC main ground wire to the ground lug on the chassis. A green
ground wire with yellow stripe connects the controller to the ground lug.
If power is off for some time, turn off the air and fuel supply.
Install a power switch near the sensor. The sensor uses non-incendive circuits, and therefore does
not have a power switch. A suitable power switch should be installed so that power can be easily
disconnected for servicing the analyzer.
Use conduit seals or cable glands to seal wiring entrances. These are required if an air purge
system is connected.
Use size 14 AWG wire (or equal) for power. Do not exceed the maximum recommended length of
AC power wires for different wire gauges as indicated in the table below.
Access to wiring terminals is at the rear of the controller. Terminals plug in to the controller.
Access terminals by lifting the controller up, and swinging the top down, leaving two bottom pins in
place. Unplug terminals to remove controller.
Install a small service loop in wire leads. Prevent strain on the terminals, and allow free movement
of the controller for access during service.
AWG
12
14
16
Maximum Length of AC Power Leads
Maximum length of wire from AC source to single analyzer
Metric
(diameter)
Feet
Meters
2,0mm
1000
305
1,6mm
600
183
1,3mm
350
107
PrevEx®InstructionManual
35
INSTALLATION
4.10.
RS-485 Serial Communications
Serial communications enables remote monitoring for improved service and troubleshooting.
Observe correct grounding and AC wiring. Damage can occur if common-mode voltages are
exceeded. Devices, which share the RS-485 connection, must all be grounded to the same common
grounding point. If a DC powered master device is used, connect the (-) DC power common to earth
ground.
Use shielded 22 AWG (metric 0,6mm) three-conductor wire such as ―Belden 3106A‖ or equal.
Use foil inner shielding with an overall braided shield. Installation of a spare is recommended.
Keep RS485 wiring separate from AC wires in metallic conduit to minimize RFI and EMI.
Protect RS-485 wires from excessive temperature and humidity, to avoid wire damage, aging,
shorting and signal loss.
The maximum line length of the RS-485 three-conductor is 4,000 feet. For greater distances a
repeater is required.
Connect wires in parallel. For multiple sensors, join all (+) connections, join all (-) connections,
and join all common (grounds). Use a ―daisy-chain‖ configuration. The maximum recommended
―stub length‖ (length of branch circuit) is ten feet.
Ground the shield drain wire at a single point. Keep the shield and drain wire insulated from
conduit and junction boxes. Interconnect the shields on each segment of cable, but attach the shield
to ground only at a single ground point.
Install wire with a small service loop to prevent strain on the terminals and to allow access to the
terminals for service procedures.
MODBUS MASTER DEVICE
RTU MODE
HALF-DUPLEX
RS-485
WARNING: FAILURE TO USE A COMMON GROUND POINT FOR ALL
DEVICES MAY RESULT IN PERMANENT DAMAGE.
!
COM D
D
FOR A DC POWERED MASTER DEVICE, CONNECT THE (-) POWER INPUT TO THE PROTECTIVE EARTH GROUND.
SHIELD
GROUND
POINT
COMMON GROUND (PROTECTIVE EARTH) BUS FOR ALL DEVICES
36
Control Instruments Corp.
35 36 37
AC POWER
+ 485 Data +
Ground
9 10
PORT
8
RS 485
7
SERIAL - 485 Data -
4-20
mA
Ground
6
4-20 Signal
5
OUTPUT
4
CONTROL 1
No connection
3
CONTROL 2
2
COMMON
1
No connection
35 36 37
AC POWER
+ 485 Data +
Ground
9 10
PORT
8
RS 485
mA
4-20
7
SERIAL - 485 Data -
CONTROL 1
6
Ground
5
4-20 Signal
4
OUTPUT
3
CONTROL 2
No connection
2
COMMON
1
No connection
35 36 37
AC POWER
+ 485 Data +
Ground
9 10
PORT
8
RS 485
7
SERIAL - 485 Data -
4-20
mA
Ground
6
4-20 Signal
5
OUTPUT
4
CONTROL 1
No connection
3
CONTROL 2
2
COMMON
1
No connection
JOIN SHIELDS TOGETHER
DO NOT GROUND SHIELD
AT ANALYZERS
INSTALLATION
4.11.
Relays and Outputs
4.11.1.
No connect ion
1
No connect ion
2
3
COMMON
4-20mA Signal Output
1. The sensor non-isolated 4-20mA output can drive a maximum
load of 275 ohms, non-inductive, including line length.
2. Use shielded 22 AWG (metric 0,6mm) shielded twisted-pair
wire such as Belden 83319E or Alpha 2824/2 or equal.
3. The 4-20 milliamp signal is self-powered. It is not looppowered, and should not be connected to a power source.
4
CONT ROL 2
4-20 m A
OUT P UT 4-20 Signal
6
Ground
RS 485
SERIAL - 485 Dat a P ORT
+ 485 Dat a +
8
1. Do not exceed the 60-Watt relay contact ratings. All contacts are
rated for 60 Watts, non-inductive loads. Exceeding the rated power or
voltage will damage the controller.
2. Use the FAULT and DANGER relays. The fault and danger relays
should be used in the safety shutdown system.
11 12 13 14 15 16 17 18 19 20 21 22 23
SERVICE
NEEDED
FAULT
DANGER
W ARNING
HORN OR
AIR/FUEL
CAL IN
P ROGRESS
SP AN
VALVE
GROUND
HEAT ER
THERMOSTAT
OR JUMPER
AC P OW ER
0,5 A
T ype T
N
L
5A
T ype F
24 25 26 27 28 29 30 31 32 33 34 35 36 37
ZERO
VALVE
5 x 20mm FUSES
9 10
RELAYS 60 W ATTS NON-INDUCTIVE, SHOW N DE-ENERGIZED
CONTROL INSTRUMENTS 600 SERIES ANALYZER CONTROLLER - SEE NAMEPLATE FOR ASSEMBLY# AND RATINGS
Ground
7
5
Relays
4.11.2.
CONT ROL 1
PrevEx®InstructionManual
3. The label shows each relay in its de-energized state.
ND - normally de-energized relay. ―Energize to trip.‖
NE - normally energized relay. ―De-energize to trip.‖
Form
Normal
State
SERVICE
NEEDED
A
ND
FAULT
C
NE
DANGER
C
NE
WARNING
C
NE
A
ND
Name
HORN
OR
AIR/FUEL
CUTOFF
CALIBRATION
IN PROGRESS
A
ND
Function
Operating properly, but service
needed soon to prevent fault.
Fault. Analyzer cannot make a valid
readings or alarms.
Reading above DANGER setting in the
ALARMS menu
Reading above WARNING setting in
the ALARMS menu
HORN Activates whenever FAULT,
WARNING or DANGER first occurs. Is
silenced by the acknowledge
command. HORN can be made NE
using FAILSAFE setting in ALARMS
menu.
Can be configured as AIR/FUEL cutoff
using RLY/CNFG setting in the
OUTPUTS menu
Activates when ZERO or SPAN are on
to indicate that analyzer is exposed to
test gases and cannot make valid
process readings or initiate a
WARNING or DANGER alarm.
4. Use failsafe relay wiring for WARNING, DANGER and FAULT.
These are ―normally energized.‖ They de-energize for an alarm or
power loss. Use a normally open contact that closes when energized,
so that a disconnected wire is detected.
37
INSTALLATION
Wiring for EMC (Electromagnetic Compatibility)
Shielded control cables, surge suppressors, and installation of ferrite beads, are required to suppress
electromagnetic interference. Control cables for the 4-20 milliamp signal, RS-485 communications
link, relays, and CONTROL inputs shall be shielded with an inner foil shield and an overall braided
shield. Ferrite beads (250 Ohms at 100 Megahertz) shall be placed near the controller‘s terminals.
Shields and ferrite beads are not required for the internal wiring or the AC power wiring on terminals
#24 to #37.
Type F
Type T
AC POWER
5 x 20mm FUSES
0,5 A
5A
OR JUMPER
HEATER
THERMOSTAT
SPAN
GROUND
CAL IN
PROGRESS
ZERO
24 25 26 27 28 29 30 31 32 33 34 35 36 37
VALVE
HORN OR
AIR/FUEL
WARNING
DANGER
FAULT
NEEDED
Ground
11 12 13 14 15 16 17 18 19 20 21 22 23
SERVICE
PORT
+ 485 Data +
9 10
8
RS 485
7
SERIAL - 485 Data -
CONTROL 1
6
Ground
5
4-20 Signal
4
4-20 mA
OUTPUT
3
CONTROL 2
2
No connection
No connection
1
COMMON
4.12.
Controller wiring with shielded cables and ferrites on control cables.
FERRITE BEAD
(SHOWN OPEN)
TO CONNECTIONS
AT ANALYZER
Installation of ferrite bead on control wiring. Remove outer insulation and shields. Fit
wires into center and snap shut. Keep wires short. A tight fit is best.
“Star” (left), and “Ring” or “Daisy-chain” (right) configurations
For “star” configuration wiring, cut off the drain wire. For “daisy-chain” wiring, in which a single
terminal has both an incoming and outgoing wire, join the drain wires together as shown.
38
Control Instruments Corp.
INSTALLATION
4.13.
Remote Control Inputs
Two inputs are provided. They are programmed as CONTROL1 and CONTROL2 in the OUTPUTS
menu. Each can perform one of the commands in the COMMANDS menu.
Manual RESET and ACKNOWLEDGE pushbuttons for alarms.
Local MENU and SELECT pushbuttons to allow access without removing the cover.
Key switch or PLC control to initiate calibration.
Prevent unauthorized calibrations and phototransducer access using LOCK CAL.
See sections 5.4 and 12.4 for descriptions of the available commands.
1. Three terminal block positions are available for CONTROL1, CONTROL2, and a ground wire.
2. Use a normally open, momentary contact, dry circuit, relay or switch.
3. Use 22 or 24 AWG wire (metric 0,5mm to 0,6mm) with a braided shield.
4. Activate with a contact closure, 250 milliseconds or more, from control input to common.
5. Controls are self-powered. Do not attach AC or DC powered control signals to controls.
REMOTE CONTROL WIRING, TYPICAL, MULTIPLE ANALYZERS
USE CONTROL1 AND/OR CONTROL2 CONNECTIONS. COMMON NOT USED.
WIRE GAUGE 22 or 24 AWG TYPICAL
SELF-POWERED 24 VDC OPEN CIRCUIT, HIGH IMPEDENCE, LOW CURRENT.
!
WARNING: FAILURE TO USE A COMMON GROUND POINT FOR ALL
DEVICES MAY RESULT IN PERMANENT DAMAGE.
COMMON GROUND (PROTECTIVE EARTH) BUS FOR ALL DEVICES
REMOTE CONTROL WIRING, TYPICAL, SINGLE ANALYZER
No connection
1
No connection
2
3
COMMON
4
CONTROL 2
4-20 Signal
7
Ground
8
RS 485
Ground
+ 485 Data +
PrevEx®InstructionManual
9 10
SERIAL - 485 Data -
PORT
6
4-20 mA
OUTPUT
5
CONTROL 1
USE CONTROL1 AND/OR CONTROL2 CONNECTIONS, AND COMMON.
WIRE GAUGE 22 or 24 AWG TYPICAL
SELF-POWERED 24 VDC OPEN CIRCUIT, HIGH IMPEDENCE, LOW CURRENT.
USE NORMALLY OPEN CONTACT.
USE PUSHBUTTON OR KEYSWITCH WITH SPRING RETURN.
39
35 36 37
AC POWER
+ 485 Data +
Ground
9 10
PORT
8
RS 485
7
SERIAL - 485 Data -
CONTROL 1
6
Ground
5
4-20 Signal
4
4-20 mA
OUTPUT
3
CONTROL 2
2
No connection
No connection
1
COMMON
35 36 37
AC POWER
+ 485 Data +
Ground
9 10
PORT
8
RS 485
7
SERIAL - 485 Data -
CONTROL 1
6
Ground
5
4-20 Signal
4
AT END, CUT DRAIN WIRE,
DO NOT GROUND SHIELD
AT ANALYZER
4-20 mA
OUTPUT
3
CONTROL 2
AC POWER
2
No connection
1
No connection
35 36 37
+ 485 Data +
Ground
9 10
PORT
8
RS 485
7
SERIAL - 485 Data -
CONTROL 1
6
Ground
5
4-20 Signal
4
4-20 mA
OUTPUT
3
CONTROL 2
No connection
2
COMMON
No connection
1
COMMON
JOIN SHIELDS TOGETHER
DO NOT GROUND SHIELD
AT ANALYZERS
JOIN SHIELDS TOGETHER
DO NOT GROUND SHIELD
AT ANALYZERS
INSTALLATION
4.14.
Visual and Audible Alarms and Indicators
Install audible and visual devices to alert personnel in the vicinity of the analyzer. At a safe distance
from the process, install a display that gives the reading and alarm status of the analyzer.
The analyzer reading (%LFL) should be displayed at the control panel where adjustments to the
process are made that might affect the concentration of flammable gases. The operators should
understand the meaning of the analyzer reading, and how it relates to the process under control.
A large, distinctive visual and audible alarm, easily observed and heard from all working locations,
should be used to alert personnel to the presence of an alarm.
The danger and fault alarms should be used for an immediate safety shutdown to bring the
concentration of flammable gases in the process safely down to 0%LFL. The warning alarm can be
used to slow down or stop the process in an orderly manner, so that a danger alarm is avoided. But in
any case, the danger alarm must safely bring the process to a halt.
The analyzer is installed close to the atmosphere being sampled. During alarms, the atmosphere may
become flammable or explosive. Avoid the area near the analyzer during alarms, until it is known
that the concentration of flammable gas has been brought to 0%LFL.
WARNING!
During alarms, keep at a safe distance until the cause is found and corrected.
4.15.
Security
Prevent accidental or unauthorized calibration or other changes to the settings and alarms.
WARNING!
The enclosure should be locked to secure the analyzer against tampering.
Secure the analyzer from unintentional or unauthorized changes:
Lock the outer cover to prevent access to the MENU and SELECT pushbuttons. The cover latches
allow the use of a padlock. The cover also requires a tool to open; this tool-operated safety feature
should not be removed.
Secure the analyzer from unintentional or unauthorized calibration:
The calibration procedure must not interfere with the analyzer‘s safety function. The person
responsible for overall process safety must implement an effective design. Several methods are
available to prevent the start of calibration or to signal that calibration is in progress.
Hardware lock
Use the OUTPUTS menu to configure the remote control input CONTROL1 or CONTROL2 with the
command LOCK CAL, and interlock this control to the process or machine controls so that calibrations
are prevented except when the machinery or process is in a safe condition.
Hardware relay output
Interlock the CAL IN PROGRESS relay with an appropriate machine control so that an inadvertent
activation of calibration immediately initiates a safety shutdown or some other safe state.
Hardware milliamp output
The MA CAL register can force the milliamp output to a special state during calibration, so that the
control or supervisory system can detect that a calibration has begun and force the process to a safe
state.
Software lock
Lock out phototransducer access by using LOCK CAL on the COMMANDS menu or with serial
communications. It will prevent the initiation of calibration until the UNLOCK command is given. The
CAL LOCK register (read-only) indicates LOCKED or UNLOCKED status.
40
Control Instruments Corp.
DISPLAY, INDICATORS, CONTROLS
5.
Display, Indicators, Controls
The controller has an alphanumeric LCD display with 10 status indicators. The display is controlled
by MENU and SELECT pushbuttons, or by phototransducers that allow access with the cover in place.
When the menus are not in use, the flammability reading is displayed. Messages for alarms and
faults are displayed once every ten seconds.
Alarm
Scan
FAULT
Menu
DANGER WARNING
HORN
ZERO
SPAN
IGNITE
HEAT
Select
Phototransducers
5.1.
Indicators
Indicator
ALARM
Color
Red
SCAN
Green
FAULT
DANGER
WARNING
HORN
ZERO
SPAN
IGNITE
HEAT
Yellow
Red
Red
Red
Green
Green
Green
Green
Meaning
Flashes when a Fault, Danger, or Warning alarm first occurs. On steady after
alarm is acknowledged. Flashed again if RESET fails to clear the alarm.
Flashes at least twice per second during normal operation. ―Winks‖ briefly after
completing a serial communication reply.
On when a fault is present. Flashes once each ten seconds if ―service needed.‖
Indicates a high high level alarm.
Indicates a high level alarm.
The Horn LED is activated by new alarms.
On when the zero gas solenoid valve is energized during calibration.
On when the span gas solenoid valve is energized during calibration.
On during two-second ignition pulse of the high voltage spark igniter.
Turns on when the flame cell heater is on. Once the operating temperature is
reached, the heater and LED slowly cycles on and off.
Menu and Select Pushbuttons
The MENU pushbutton displays a list of menus. SELECT a menu to display its registers. Within a
menu, SELECT a register to display its value, or press MENU to go to the next register. When finished
viewing registers, press SELECT when EXIT is displayed to leave the menu and return to a scan of the
reading and status. Or, simply wait: menus are displayed for several seconds, and register values for
three minutes, after which, without pressing any pushbutton, the display will time out and exit
automatically. Some registers can be changed. Pressing SELECT while its value is displayed
increments the value to the next available setting. Once the desired value is displayed using SELECT,
wait a few seconds until the display begins to flash. Continue to wait until the flashing stops. As the
flashing stops, the new setting is entered and saved in EEPROM. To abort the change without saving
it, press MENU at some point before the flashing stops. The old value will be restored.
5.2.
PrevEx®InstructionManual
41
DISPLAY, INDICATORS, CONTROLS
5.3.
Navigation: Menus and Registers
To move through menus,
Enter menu
Show Register
Display Register
"MENU"
"SELECT"
"MENU"
"SELECT"
... and modify registers ...
Modify Register
"SELECT"
Flashes .... then completes
To accept/activate wait for
flashing to stop. To
escape/cancel, press "MENU"
COMMANDS
RESET
ACKNWLDG
ZERO CAL
SPAN CAL
FULL CAL
ZERO TEST
SPAN TEST
FULL TEST
SAVE ALL
LOCK CAL
EXIT
Clear alarms, reignite, adjust chk flow
Silence horn, clear "service needed", adjust chk flow
Calibrate to 0% with air, adjust RAW ZERO
Calibrate to CAL RDNG with test gas, adjust RAW SPAN
Calibrate both zero and span
Inject air to check 0% LFL reading - no adjustment
Inject span test gas to check reading - no adjustment
Test both zero and span
Write settings to EEPROM
Prevent activation of calibrations and tests
GAUGES
READING
STATUS
PEAK HI
PEAK LOW
HSG TEMP
SET TEMP
FLOW
LOW FLOW
CHK FLOW
FLAME
EXIT
%LFL Reading
Device status
Highest reading since last RESET
Lowest reading since last RESET
Temperature of flame cell
Temperature setting for flame cell
Sample flow rate
Flow rate below which LOW FLOW occurs
Flow rate below which CHK FLOW occurs
Flame temperature
CAL MENU
RAW ZERO
RAW SPAN
CAL TIME
CAL RDNG
SPAN °C
SPEED
CAL LOCK
EXIT
Flame temperature of zero (0% LFL)
Flame temperature rise from span test gas
Duration of calibration in minutes
Span calibration reading, %LFL
Expected RAW SPAN flame temperature rise from span gas
LOW
MED
ON
HIGH
OFF
ALARMS
WARNING
DANGER
RATE
LATCHES
FAILSAFE
AUTO IGN
VERSION
TYPE
SERIAL
LANGUAGE
EXIT
OUTPUTS
----HFDW Force relays to activate
Force milliamp output to increase
Fine tune output so 0%LFL = 4.0 mA
Fine tune output so 100%LFL = 20.0 mA
Force output during calibrations and test
Force output during faults
RESET
ACKNWLDG
ZERO CAL
HORN
SPAN CAL
AIR/FUEL
FULL CAL
OVERRIDE
ZERO TEST
SPAN TEST
SET BAUD
300
FULL TEST
BAUD RATE
600
SAVE ALL
AUTO BAUD
ON
1200
COLDSTRT
ADDRESS
1,2 ...255
OFF
2400
MENU
ID NBR
0,1,2 ... 99
4800
SELECT
EXIT
9600
LIGHT ON
19200
LOCK CAL
COM PORT
EXIT
42
To display registers
Show menu
%LFL above which WARNING is given
%LFL above which DANGER is given
Rate-of-rise alarm enable: ON or OFF
----HFDW Relay latch until RESET
----HFDW Relay normally energized
0 (off), 1, 2, ...
5.11
SNR67x
05-xxx
Display language selection
RLY TEST
MA TEST
4 MA ADJ
20 MA ADJ
MA CAL
MA FAULT
CONTROL 1
CONTROL 2
RLY CNFG
EXIT
Control Instruments Corp.
DISPLAY, INDICATORS, CONTROLS
5.4.
COMMANDS
RESET and ACKNWLDG are the only commands used by the operator. They are accessible with the
CAL LOCK active. All other commands are for calibration and maintenance, and should be secured
against unauthorized or unintentional activation with a software or hardware lock.
RESET
The RESET command deactivates latched warning or danger alarms or faults if the
condition that caused the alarm or fault has been corrected. If the status is a
FLAMEOUT fault, RESET initiates re-ignition. The IGNITE indicator momentarily
activates as a high voltage spark discharge is generated in the flame cell. RESET also
adjusts the flow rate for the CHK FLOW , SERVICE NEEDED message.
ACKNWLDG
The ACKNOWLEDGE command deactivates the HORN indicator and relay16, and stops
the flashing of the ALARM indicator. ACKNWLDG deactivates the SERVICE NEEDED
relay and message. If a CHK FLOW , SERVICE NEEDED message was active, it adjusts
CHK FLOW so another message occurs if the flow rate continues to fall.
Calibration (CAL)commands initiate calibration. Solenoid valves inject calibration gases to the
analyzer. If the response is acceptable, the readings are adjusted; else a calibration fault is activated.
Hardware faults, which might make calibration inaccurate, cause the calibration to abort.
ZERO CAL
Injects Zero Gas and updates RAW ZERO to give a 0%LFL reading. If the response is
bad, a ZERO FAIL fault occurs.
SPAN CAL
Injects Span Gas and updates RAW SPAN to give a %LFL reading equal to CAL
RDNG. If the response is bad, a SPAN FAIL fault occurs.
FULL CAL
Performs a zero calibration, followed by a span calibration.
TEST commands
do not calibrate, they only inject calibration gases. They do not adjust readings, and
do not generate faults. They are permitted when a fault exists. Use TEST commands for
troubleshooting only.
ZERO TEST
Injects Zero Gas, so the response can be observed.
SPAN TEST
Injects Span Gas, so the response can be observed.
FULL TEST
A combined zero and span test.
SAVE ALL
Saves all settings to nonvolatile EEPROM. Calibration automatically saves all.
The commands LOCK CAL and UNLOCK are for security. One or the other appears as appropriate.
LOCK CAL
Prevents calibration and test commands from being activated until the UNLOCK
command is given. With the lock on, only the ―RESET, ACKNOWLEDGE and
EXIT‖ are available.
UNLOCK
Enables calibration and test commands. Does not override a hardware lock on the
CONTROL1 or CONTROL2 input.
Section 12.4 includes COMMANDS that are accessed through serial communications only.
16
Acknowledge deactivates the relay only if the RLY CNFG setting is ―HORN.‖ See section 2.6.11for details.
PrevEx®InstructionManual
43
DISPLAY, INDICATORS, CONTROLS
5.5.
GAUGES
The GAUGES menu has registers for the reading, status and operation. All are read-only, except for
SET TEMP and LOW FLOW , which can be adjusted, but normally require none.
READING
STATUS
PEAK HI
PEAK LOW
HSG TEMP
SET TEMP
FLOW
LOW FLOW
CHK FLOW
FLAME
The flammability reading in %LFL.
The device status.
The highest reading since last reset, excluding warm-up and calibration.
The lowest reading since last reset, excluding warm-up and calibration.
The flame cell temperature in °C. It should be equal to SET TEMP.
Sets the flame cell temperature in °C. The controller turns the heater on and off in
order to keep the HSG TEMP equal to SET TEMP, typically, within ±2°C.
The sample flow rate in standard liters per minute, (SLPM).
The sample flow rate below which a FAULT is activated.
The sample flow rate below which a CHK FLOW message is activated.
The flame temperature in °C. At 0%LFL, the typical flame temperature is 500°C.
5.6.
CAL MENU
The CAL MENU contains registers that control calibration.
RAW ZERO
RAW SPAN
CAL TIME
CAL RDNG
SPAN °C
SPEED
The flame temperature taken during the last successful zero calibration.
Rise in flame temperature above the zero, from the last successful span.
Sets the number of minutes that the zero and span gases are injected during
calibrations and tests.
Sets the reading for span calibration. It is the flammability of the span gas including
the response factor and temperature correction.
Sets the expected temperature rise for the span gas response during span calibration.
If the response of the sensor is not close to this value, a CHK SPAN message or SPAN
FAIL fault will be given.
Sets the speed of response for the sensor. The HIGH setting gives the fastest
response; the LOW setting has an additional delay that can reduce the rate of rise of
the reading. The speed register controls a digital noise filter, which introduces a
small time delay, but increases noise immunity. Some Model types allow the speed
to be turned OFF, which delays the response about ten seconds.
LOW
Slowest setting. Adds up to 0.25 seconds to the response time.
MED
HIGH
CAL LOCK
Default setting.
Fastest possible response time. Reduces response time by 0.25 seconds.
Indicates the state of CAL LOCK. Either LOCKED or UNLOCKED.
The setting LINEAR appeared in prior versions, but is no longer included in the CAL MENU:
LINEAR
LINEAR sets the linear range for the air dilution option. When air dilution is
uninstalled or OFF, and/or the sensor operating in the standard configuration, this
setting should be 40% LFL. With air dilution ON, this setting should be 80% LFL.
44
Control Instruments Corp.
DISPLAY, INDICATORS, CONTROLS
5.7.
ALARMS
The ALARMS menu contains registers related to the warning and danger alarms, and the device
identification. These registers are for configuration only, and do not normally require adjustment.
WARNING
DANGER
RATE
LATCHES
FAILSAFE
AUTO IGN
VERSION
TYPE
SERIAL
LANGUAGE
Sets the WARNING alarm level. When the flammability reading exceeds the warning
level, the warning LED indicator and relay are activated. If configured to be a
latching alarm, the warning remains active until the flammability reading goes back
below the warning level and the reset command is given. Otherwise, the warning
LED indicator and relay are deactivated once the flammability reading goes back
below the warning level. The WARNING alarm is automatically activated whenever
the DANGER alarm is active.
Sets the DANGER alarm level. When the flammability reading exceeds the danger
level, the warning and danger indicators and relays are activated. These remain
active until the flammability reading goes back below the danger level and the reset
command is given, or an auto reset occurs.
Enables or disables the RATE alarm. If the rate of rise of the flammability reading is
such that it will soon exceed the danger alarm level, the danger alarm is activated.
Configures the warning, danger, fault and horn to latch. A latching alarm is kept
active, even if the condition that caused the alarm is corrected, until it is cleared by
the reset command. The value of the LATCHES register is displayed as the first letter
of each alarm. The display - - - - HFDW means that the HORN, FAULT, DANGER and
WARNING are latching. When the DANGER alarm is not latching, an external device
must be provided to perform the latching function.
When the HORN is configured to latch, a RESET that does not result in a NORMAL
status causes the HORN to re-activate. When the horn is configured to auto reset,
only a new alarm, and not a reset attempt, re-activates the horn.
An AUTO IGN setting of 1 or more can override the LATCHES setting for flameout
faults that successfully re-ignite.
Failsafe relays are normally energized; they de-energize when the alarm activates. If
power is lost, or another fault de-energizes the relay, the relay contacts switch.
WARNING, DANGER and FAULT relays are failsafe. The HORN, if not essential to the
safety system, can be made non-failsafe so that it is silent during maintenance
procedures. FAILSAFE displays the first letter of each failsafe alarm. - - - - - FDW
means the horn is not failsafe, - - - - HFDW means the horn is failsafe.
Configures automatic re-ignition of the sensing flame. When set to 0, this feature is
turned off, and there is a single attempt to ignite the sensing flame. When 1 or more,
up to a limit of 120, there are additional re-ignition attempts at 15-second intervals.
If re-ignition is successful, and there are no fault conditions, normal operation
resumes as if an alarm reset had occurred, regardless of the setting of the LATCHES.
Displays software version.
Displays the analyzer type and matches the device software to the model number on
the serial plate, for example SNR671.
Displays the serial number that was programmed at the factory during assembly.
Configures language, for example ENGLISH/DEUTSCH (German).
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45
DISPLAY, INDICATORS, CONTROLS
5.8.
OUTPUTS
This menu contains registers for configuring and testing the relays, controls and analog output.
RLY TEST
Test relay activation. Only accessible through the menu. Not accessible through
serial communications. The relay test register allows the relays to be tested by
activating them. The register is displayed as the first letter of each relay, - - - - HFDW
means the HORN, FAULT, DANGER and WARNING relays are activated. When the
OUTPUTS menu is exited, the test ends, and relays activated by the test are
deactivated. It is not possible to deactivate relays using the test register.
MA TEST
Test milliamp output. Only accessible through the menu. Not accessible through the
serial communications. The test register allows the milliamp output to be increased
to a higher level. In order to make the test failsafe, it is not possible to decrease the
milliamp output. When the OUTPUTS menu is exited, the test ends, and the milliamp
output is decreased to the correct value.
4 MA ADJ
Adjusts the milliamp output circuit so that 4 milliamps = 0%LFL. The 4 MA ADJ
value is added to the output. For example, if the actual output is 3.9 milliamps at
0%LFL, set 4 MA ADJ to 0.1 milliamps to obtain 4.0 milliamps at 0%LFL.
20 MA ADJ
Adjusts the milliamp output circuit so that 20 milliamps = 100%LFL. The 20 MA ADJ
value is added to the output. For example, if the actual output is 19.0 milliamps at
100%LFL, set 20 MA ADJ to 1.0 milliamps to obtain 20.0 milliamps. To adjust, use
MA TEST to get a 20.0 milliamp output, then measure the actual output, and make 20
MA ADJ equal to the difference between the actual and 20.0 milliamps.
MA CAL
Sets the milliamp output during calibration. May be adjusted from 2.5 to 22.7
milliamps. If ―OFF‖ is displayed, the register is not used, and the output equals the
flammability reading during calibration. If any other value is used, then the milliamp
output is forced to the MA CAL value during calibration.
MA FAULT
Sets the milliamp output during faults. May be adjusted from 2.5 to 22.7 milliamps.
If ―OFF‖ is displayed, the register is not used, and the output equals the
flammability reading during faults, even if the flammability reading is inaccurate. If
any other value is used, faults force the milliamp output to the MA FAULT value.
CONTROL1
Configures the remote control #1 to execute a command. This register allows one of
the commands to be assigned to CONTROL1. When the CONTROL1 input is activated,
the command is executed. See the COMMANDS menu in section 5.4 and the
COMMANDS register in section 12.4 for a list of commands.
CONTROL2
Configures the remote control #2 to execute a command.
RLY CNFG
Reconfigures the HORN relay for use as an AIR/FUELcontrol. See section 2.6.11.
HORN
Default operation, relay performs HORN function.
AIR/FUEL
Configuration for controlling solenoid valves to automatically turn
off air and fuel to the analyzer. The relay energizes (contact is
closed) at the proper operating temperature. The relay de-energizes
(contact is open) if temperature is too low, or if flame remains unlit
after re-ignition attempts are unsuccessful.
OVERRIDE
The relay is forced to energize (contact is closed) to manually
override the AIR/FUEL CONTROL function.
The setting MA SCALE appeared in prior versions but is no longer included in the OUTPUTS menu:
MA SCALE
MA SCALE displays the reading equal to 20 milliamps, typically 100 %LFL.
46
Control Instruments Corp.
DISPLAY, INDICATORS, CONTROLS
5.9.
COM PORT
This menu configures the serial communications port. The character length is always 8 bits with one
stop bit and no parity. The baud rate is adjustable, and can be made automatic.
SET BAUD
BAUDRATE
Sets the default baud rate between 300 and 19,200 baud. If AUTOBAUD is OFF, the
default baud rate is used.
The baud rate actually in use by the device. If AUTOBAUD is OFF, BAUDRATE equals
If AUTOBAUD is ON, BAUDRATE slowly searches from 300 and 19200
baud until successful communications occur.
SET BAUD.
AUTOBAUD
Activates automatic baud rate detection. After several consecutive unsuccessful
attempts to communicate, the baud rate is changed, until communications are
established.
ADDRESS
Sets the devices address to a number from 1 to 255. Each device that is connected to
the same serial communications wire must have its own unique address.
ID NBR
Allows an identification tag number between 0 and 99 to be assigned by the user.
Flashlight-activated Commands
Phototransducers located just below the MENU and SELECT pushbuttons allow access to COMMANDS
when the enclosure cover is on.
5.10.
Alarm
Scan
FAULT
Menu
DANGER WARNING
HORN
ZERO
SPAN
IGNITE
HEAT
Select
Phototransducers
1. Cover the left and right phototransducers with fingertips.
2. Shine a flashlight on the center phototransducer.
3. Commands will appear in the display, one at a time, every few seconds. Only RESET and
ACKNOWLEDGE commands appear when the CAL LOCK is active.
4. When the desired command appears, remove the flashlight and uncover the left and right
phototransducers. To exit without executing a command, use the EXIT command.
5. The selected command flashes for several seconds before activating.
6. Once the command activates, flashing stops, and the reading and status is displayed.
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STARTUP PROCEDURE
6.
Startup Procedure
To be performed by qualified persons only.
6.1.
Initial conditions
Before starting, AC power, fuel pressure, air pressure and calibration pressure are all OFF. To be
safe, turn utilities on in the correct sequence as shown below.
6.2.
Air
Apply compressed air to the analyzers. Remember that the compressed air allows the analyzer to use
fuel safely. Keep the fuel and power off until the air is on and checked.
1. Temporarily disconnect air connections from analyzer(s)
2. Turn air supply pressure to a minimum value, (a few PSIG).
3. Turn air on to blow air lines clean of anything that might have accumulated.
4. Reattach air lines to each analyzer
5. Set air pressure to deliver 20 PSIG to each and every analyzer.
6. Check pressure at each analyzer.
6.3.
Fuel
Once the compressed air is on, the fuel supply can be turned on. It will take some time for the fuel
lines to purge before the fuel reaches the analyzer.
1. Visually check fuel connection.
2. Turn fuel supply regulator to low pressure.
3. Turn on fuel supply main valve.
4. Turn fuel supply regulator up to pressure indicated on serial plate.
5. Check for leaks: Shut off fuel cylinder valve and observe outlet pressure. If pressure holds
steady more than 5 minutes, there are no significant leaks. If pressure drops suddenly there
are leaks. If pressure does not hold for at least 30 seconds, the main valve must be left off
until all connections are checked and the leak is found and fixed, or else the fuel cylinder
will empty itself.
6. Turn on main fuel valve.
The fuel supply will begin to purge trapped air from the lines. This can take ½ to a few hours,
depending on the fuel system design.
6.4.
Power
Carefully check the wiring before turning power on.
1. Check wiring for misconnections and short.
2. Look for loose strands on terminals.
3. Measure from AC input to ground, should be open circuit
4. Check relay connections for compatibility. If in doubt unplug relay connections until they
can be proven.
5. Turn power on.
Analyzer has “TEMP LOW” fault. Heater is on. Fault indicator on. Alarm on, or flashing.
Analyzer begins to heat up. Depending on the starting temperature and operating temperature, after
½ hour to 1½ hour, the analyzer reaches operating temperature, and the heater cycles on/off.
Analyzer may still be in fault condition “FLAMEOUT.”
48
Control Instruments Corp.
STARTUP PROCEDURE
6.5.
Ignition
Once fuel lines have purged so fuel reaches the analyzers, and the analyzer is up to its operating
temperature, and there are no other faults except “FLAMEOUT,” the sensing flame can be lit.
1. The analyzer may automatically ignite itself. If not, use RESET on the COMMANDS menu to
start the ignition process.
2. Use the FLAME register to see if the flame is lit.
3. Check the settings and reading on the GAUGES menu.
4. To repeat the ignition attempt, use RESET on the COMMANDS menu again.
AUTOIGN on the ALARMS menu can be configured to automatically make re-ignition attempts.
REGISTER
Description
READING
Until flame is lit, reading is negative, usually below -35% LFL, typically -99 %LFL or less.
Once flame is lit, reading is higher, usually above -35% LFL, and climbs up slowly as fuel
lines purge and analyzer stabilizes. It finally settles out near 0%LFL.
STATUS
When power is first applied, STATUS is TEMP LOW until analyzer heats up.
With air on and the analyzer up to temperature, STATUS will be FLAMEOUT.
HSG TEMP
When up to temperature, is equal to SET TEMP
SET TEMP
Depends on TYPE.
FLOW
Should be higher than LOW FLOW or else a fault exists.
LOW FLOW
Factory set, usually 1.4 LPM.
FLAME
Until the flame it lit, the reading is about the same as HSG TEMP.
Once the flame is lit, FLAME is much higher than HSG TEMP, and it continues to rise as the
fuel lines purge and the analyzer‟s temperature stabilizes. The controller indicates
FLAMEOUT until the FLAME is above 450°C. It eventually settles near 500°C.
Avoid adjusting the fuel regulator to try to bring the flame up. Wait for fuel lines to purge
completely, until then the flame will be smaller than normal. Wait for the fuel system and analyzer to
stabilize before making any adjustments.
6.6.
Preliminary Calibration
Check calibration line for leaks. Perform a preliminary calibration and check results.
1. Briefly turn calibration cylinder main valve on and then immediately off to pressurize the
calibration lines.
2. Observe the calibration cylinder tank pressure. It should hold constant for at least 5 minutes.
If not there is a leak that must be eliminated or else the calibration cylinder will empty itself.
Check all connections and repair any leaks before proceeding.
3. Turn calibration cylinder(s) on.
4. Use FULL CAL on COMMANDS menu to initiate the automatic calibration sequence.
5. For each analyzer, observe the reading during the calibration process.
Zero indicator is on.
After about one minute (CAL TIME on CAL MENU) reading is near 0%LFL.
Zero is off. Span comes on.
Reading climbs up to near CAL RDNG, typically about 60%LFL.
Within one minute reading is very near CAL RDNG.
Span LED off. Zero LED back on for about 30 seconds to purge. Reading falls back
toward 0%LFL.
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STARTUP PROCEDURE
6.7.
Inputs and outputs
Check the 4 - 20 milliamp output and set up its “special states.” Configure the controls. Check the
alarm levels, Test the relays. Verify the E-Stop.
6.7.1.
4 - 20 milliamp output
The 4 MA ADJ AND 20 MA ADJ settings or the 4 - 20 milliamp output do not normally require
adjustment. Prior to adjustment, record the settings for future reference.
1.
2.
3.
4.
5.
6.
6.7.2.
Use MA TEST on OUTPUTS menu.
Output 4 ma. Only if necessary adjust 4 MA ADJ on OUTPUTS menu.
Output 20 ma. Only if necessary adjust 20 MA ADJ on OUTPUTS menu.
When adjustments have been made check at 4, 12, and 20 milliamps.
Set MA FAULT, the milliamp output during faults, for desired effect.
Set MA CAL, the milliamp out during calibration, for desired effect.
Controls
1. Configure CONTROL1 and CONTROL2 on outputs menu for desired effect.
2. Configure security for CAL LOCK or CAL IN PROGRESS.
6.7.3.
Alarms and Relays
1.
2.
3.
4.
5.
Check relay wiring for misconnections and shorts.
Check WARNING and DANGER levels in ALARMS menu.
Use RLY TEST in OUTPUTS menu to activate relays.
Verify that actions of each relay produce the desired overall result.
Verify that the FAULT and DANGER relays activate the E-Stop (safety shutdown).
6.8.
Records
For future reference, create a permanent written record of all settings and values.
6.9.
Stability test
After the first 24 to 72 hours of operation the analyzer and all its utilities should be stable. Test
accuracy with calibration gases and check results. If the zero and span values have not drifted
significantly, the analyzer and its utilities have stabilized, and are ready for a complete calibration,
see section 7.
on the GAUGES menu should be between 495°C and 505°C. The zero and span should be
within +/-1%LFL of the correct values. If the drift is greater than 1%, perform a recalibration, and
repeat the stability test once more, after another 24-hour period has passed.
FLAME
1. Turn calibration cylinder(s) on.
2. Use FULL TEST on COMMANDS menu to initiate the automatic test sequence.
3. For each analyzer, observe the reading during the calibration process.
Zero indicator is on.
After about one minute (CAL TIME on CAL MENU) reading is near 0%LFL.
Zero is off. Span comes on.
Reading climbs up to near CAL RDNG, typically about 60%LFL.
After about one minute reading is near CAL RDNG.
Span LED off. Zero LED back on for about 30 seconds to purge. Reading falls back
toward 0%LFL.
50
Control Instruments Corp.
CALIBRATION
7.
Calibration
To be performed by qualified persons only.
WARNING!
The accuracy of the analyzer, and its ability to make alarms, depends completely
upon proper calibration. Follow all calibration instructions carefully.
Calibration adjusts the analyzer for accurate %LFL readings. First, an initial calibration verifies
important aspects of the calibration and its configuration, and determines the correct calibration
reading17 - CAL RDNG. Thereafter, routine recalibrations are performed on a regular basis to maintain
accuracy and to verify the response. If any fact affecting the initial calibration changes, the initial
calibration process should be repeated.
7.1.
Initial calibration
Perform the initial calibration before the analyzer is put into service, and whenever process changes
are made, especially changes to the types of flammable gases being measured, the span calibration
gas, or the process temperature. Maintain a permanent record of all calibration information.
Review of limitations
Prior to putting the analyzer into service, review the ―Theory of Operation‖ section for limitations to
its effective operation. Include all foreseeable changes. Any limitation that might adversely affect the
reliability of the analyzer should preclude its use until a correction can be found.
Identification of all flammable gases to be measured
List all flammable gases to be measured, now or in the future, in the record of initial calibration.
Include the name, the LFL value, the Flash Point, and the response factor.
Response factors for different flammable gases
A response factor compares a particular gas to the standard calibration18. If the standard calibration is
completely accurate for the gas of interest its response factor is 1.0. A low response factor means low
readings: the calibration reading should be increased to make readings accurate. A high response
factor means a gas has an exaggerated response compared to the standard - a ―safe side‖ error19. The
sensing flame has uniform response factors for many gases. Most solvent vapors have response
factors between 0.9 and 1.1. They can be measured within the analyzer‘s specified accuracy using
the standard calibration, so correction for different solvents is often unnecessary.
Flash Point verification
Make certain the Flash Points of any and all flammable gases to be monitored are less than the
operating temperature of the analyzer and all parts of the sampling system. The Flash Point of each
individual flammable gas is important, not only the Flash Point for the complete mixture.
17
The calibration reading is determined according to code requirements. There is one method for FMc and FM
approved types, and another for ATEX/CENELEC types. The results are similar but not identical.
18
Response factors are not based on the LFL value of the calibration gas itself. The calibration gas is only used
to create a known, predictable increase in the flame temperature. Do not change the calibration reading when
the local authority publishes a different LFL value of the calibration gas itself.
19
The error due to response factor variation is the actual %LFL reading times (R gas - Rcal), where Rcal is the
response factor used for the calibration (typically 1.0 for the standard calibration), and R gas is the response
factor of the gas that is actually present. If more than one gas is actually present, R gas is the weighted average of
all response factors, where the weighing factor is each gas‘s percentage of the total %LFL reading.
PrevEx®InstructionManual
51
CALIBRATION
7.1.1.
Calibration reading for FM and FMc type analyzers
Standard calibrations
approved for FM and FMc type analyzers
with 7.84% per 100°C temperature correction factor per NFPA-86, suitable for the standard solvents
FM and FMc approved models are calibrated with 1.15% by volume ethylene in air within a 2% tolerance.
Ethylene in air between 1.13% and 1.17% by volume is an acceptable calibration span gas.
The calibration reading is adjusted for higher temperatures per the NFPA-86 code, which requires a 7.84% increase
in CAL RDNG for each 100°C increase in process temperature.
CAL RDNG
Process temperature
1.15% Ethylene in Air = 50% LFL of standard solvent vapors at 77°F ( 25°C)
1.15% Ethylene in Air = 56% LFL of standard solvent vapors at 250°F (120°C) per NFPA-86
1.15% Ethylene in Air = 60% LFL of standard solvent vapors at 400°F (200°C) per NFPA-86 (factory default)
1.15% Ethylene in Air = 64% LFL of standard solvent vapors at 600°F (315°C) per NFPA-86
Canadian Standards Association
(FMc)
Factory Mutual Research
(FM)
Generic Label
Models with generic labels have options not
tested and approved by a third party.
Adjusting FMc and FM type analyzers for other substances
The standard calibration is accurate for flammable gases with response factors between 0.9 and 1.1.
Response factors above 1.1 produce ―safe-side‖ error and can be ignored. Response factors below
0.9 may require correction of the calibration reading.
For mixtures of several solvents, where one has a much lower response factor than the others, Rmin, it
is safest to divide the standard calibration reading by Rmin. The higher calibration reading will give
readings for all gases in the mixture at or above their actual flammability20.
To remove some of the ―safe-side error,‖ the response factors for ―minor components‖ in the mixture
may be ignored. A minor component is a flammable gas with a low response factor, that nevertheless
is present in such small amounts in the mixture that the resulting error21 can be ignored.
If all gases being monitored have response factors greater than 1.0, it is permitted, but not necessary,
to divide the calibration reading by Rmin, the lowest response factor of all the gases, to lower the
calibration reading and remove the ―safe side‖ error.
20
Refer to National Fire Protection Association, NFPA-86 ―Ovens and Furnaces‖ for this requirement.
21
NFPA-86 indicates an error of not more than 3% of the reading. This means flammable gases with response
factors above 0.7 that are always less than 10% of the total flammable gas mixture are minor constituents. The
rated accuracy of the analyzer is 10% of the reading, which corresponds to a response factor of 0.7 that is less
than one-third of the mixture.
52
Control Instruments Corp.
CALIBRATION
7.1.2.
Calibration reading for ATEX type analyzers
Standard calibration
approved for ATEX / CENELEC types
Models SNR67x-Ty carry the ATEX and CE marks. To conform to CENELEC norms, start with the standard
calibration ―1.15% Ethylene in Air = 50% LFL.‖ Then correct for response factor(s), calibration gas type and
concentration, alternate LFL values (if any), and temperature correction (if any).
Process temperature
1.15% Ethylene in Air = 50% LFL of standard solvent vapors at 20°C
CAL RDNG
II 2 G EEx p II Tx
-20°C < Tamb < 60°C
Control Instruments Corporation
Fairfield, New Jersey, USA
0344
Model
SNR67XXXX
Free volume
18 l
Freies Volumen
Year of manufacture
0,5 mbar
Mindest- Überdruck
Serial number
XXXX
XX-XXXX
Minimum overpressure
Maximum overpressure
25 mbar
Maximaler Überdruck
Certificate number
DMT 03 ATEX G 001 X
Minimum purge volume
240 l
Mindest-Vorspülmenge
120 VAC
Minimum initial purge flow
24 l/min
Mindest-Vorspül-Volumenstrom
Propane
Minimum continuous dilution flow
14 l/min
Mindest-Volumenstrom
Voltage
Fuel type
□ 230 VAC
x Hydrogen
□
□
Adjusting ATEX / CENELEC type analyzers for other substances
To measure a particular flammable gas with maximum accuracy, divide the calibration reading by
the response factor R from the table in section 7.1.3.
For mixtures of several solvents, where one has a much lower response factor than the others, Rmin, it
is safest to divide the standard calibration reading by Rmin. The higher calibration reading will give
readings for all gases in the mixture at or above their actual flammability.
To remove some of the ―safe-side error,‖ the response factors for ―minor components‖ in the mixture
may be ignored. A minor component is a flammable gas with a low response factor, that nevertheless
is present in such small amounts in the mixture that the resulting error is insignificant. For example,
a substance with R = 0.7 at a concentration below 10% LFL causes an error less than 3% LFL using
the standard calibration.
If all gases being monitored have response factors greater than 1.0, it is permitted, but not necessary,
to divide the calibration reading by Rmin, the lowest response factor of all the gases, to lower the
calibration reading and remove the ―safe side‖ error.
Alternate calibration gases and concentration for ATEX / CENELEC type analyzers
If calibration gas is not available in concentration C0, a different concentration CC may be used
within an acceptable range. The calibration reading is multiplied by ( P * CC ) / C0 .
For ethylene, C0 is 1.15% by volume, CC must be between 1.0% and 1.2%, and P =1.
For propane, C0 is 0.91% by volume, CC may be between 0.8% and 0.95%, and P = 0.93.
Alternate Lower Flammable Limit values
Each flammable gas has its own LFL value, the percent by volume concentration in air at which that
particular gas becomes flammable. The response factors in section 7.1.3 use LFL values from several
sources. If traceability to a particular code or authority is required, compare the LFL value in section
7.1.3 with the value published by the local authority. If the values are the same, the response factor
PrevEx®InstructionManual
53
CALIBRATION
remains valid. If the LFLA value recognized by the local authority is different than the LFLR value
in the response factor table, multiply the response factor by the ratio ( LFLA / LFLR ).
Temperature correction for ATEX / CENELEC type analyzers
To reflect the increase in flammability at higher temperatures, there are two methods.
Increased calibration reading - for ATEX temperature correction
To correct the calibration reading for temperature, multiply CAL RDNG by [ 1/ (1-KT*(TA – T0)) ].
Once corrected, the analyzer readings will be accurate for the temperature TA.
TA is the temperature of mixture to be monitored, in C.
T0 is the temperature at which the LFL value was determined, in C, usually 20°C.
KT is a (gas-specific) factor for the temperature dependency, usually from 0,000784 to 0,00140.
A typical value of KT is 0,0014, which corresponds to 14% per 100°C. KT should be obtained from
the relevant standards or the local authority having jurisdiction.
Reduced or limited alarm levels - for ATEX temperature correction
If the calibration reading is not corrected for temperature, the analyzer reading means ―%LFL at
20C.‖ In this case, the alarm levels must be set to prevent operation above the maximum %LFL
concentrations permitted by code, and must still have an acceptable margin of safety for the actual
process temperature. Refer to the relevant CENELEC norm, for example, EN1539.
Calibration reading formula for ATEX type analyzers
A formula for the calibration reading for ATEX type analyzers combines all the corrections
described above:
0
0
CAL RDNG = 50%LFL * [ CC/C ] * [ 1/R ] * [ P ] * [ LFLR / LFLA ] * [ 1/ (1-KT*(TA – T )) ]
Note concerning SPAN°C - the expected span temperature
The known, predictable increase in the flame temperature during the span phase of calibration is the
setting SPAN°C. It is the RAW SPAN, the amount of temperature rise, expected from the standard
calibration gas. PrevEx analyzers have very little individual variation in sensitivity22 - the RAW SPAN
is normally between 115°C and 135°C. During calibration, RAW SPAN is compared to the SPAN °C
setting. A large deviation causes ―service needed‖ message, or fault. ―Service needed‖ occurs for
deviations greater than 13% of SPAN °C (~ 15°C). A fault occurs for deviations greater than 25% (~
30°C). If this occurs, do not adjust SPAN °C. Instead, find and fix the cause of the deviation, which
could be incorrect calibration gas concentration or pressure, incorrect alignment between the burner
and thermocouple, accumulation of debris on the thermocouple, or a leak in the sampling system.
The benefit of SPAN °C is the ability to detect a problem with the analyzer or the calibration
procedure that might otherwise go undetected.
22
Air dilution is an exception. The air dilution option decreases the calibration gas concentration in the flame
cell by about half, so the RAW SPAN and SPAN °C are approximately half their usual values.
54
Control Instruments Corp.
CALIBRATION
7.1.3.
Response Factor Table
Response factors R marked (*) were determined by DMT - Deutsche Montan Technologie GmbH - using the LFLR value given in the table and temperature
basis T0 = 20C. All others are by Control Instruments Corporation with temperature basis T 0 = 25C. Substances marked ― >‖ are standard. FP = °C Flash Point.
LFLR
> 4.00
4.00
> 2.70
> 2.50
3.00
16.00
1.10
> 1.20
> 1.20
> 1.30
> 1.50
> 1.80
> 1.40
> 1.60
> 1.70
1.50
> 1.70
1.10
1.40
2.40
1.30
12.50
> 1.70
1.30
>
R
1.00
0.82
1.06
1.01
0.83
1.74
1.14
0.90
0.94
0.94
1.10
1.01
1.00
1.06
1.00
0.88
1.00
0.78
0.76
1.00
0.83
1.22
1.02
0.81
14.00 1.00
8.10
> 1.33
1.10
1.00
1.43
1.00
0.84
0.93
Substance
acetaldehyde
acetic acid
acetic anhydride
acetone (*)
acetonitrile
ammonia
amyl acetate
amyl alcohol
benzol (*) / benzene
benzyl alcohol
butadiene
butanone (*)
n-butane
butene
butyl acetate
n-butyl acrylate
n-butyl alcohol
butyl cellosolve
butyraldehyde
butyrolactone
carbon disulfide
carbon monoxide
cellosolve acetate
chlorobenzene
chloroform /
trichloromethane
chloromethane /
monochloromethane
cyclohexane
cyclohexanone
cyclohexene
PrevEx®InstructionManual
CAS#
FP °C
75-07-0
-27
64-19-7
39
108-24-7
52
67-64-1
-20
75-05-8
2
7664-41-7
-78
628-63-7
23
71-41-0
33
71-43-2
-11
100-51-6
93
106-99-0
78-93-3
-7
106-97-8
-60
25167-67-3
123-86-4
22
141-32-2
29
71-36-3
37
111-76-2
-5
123-72-8
-12
96-48-0
98
75-15-0
-30
630-08-0
-205
110-80-5
60
108-90-7
30
67-66-3
-
74-87-3
110-82-7
108-94-1
110-83-8
0
-20
43
-12
LFLR
0.70
> 0.80
1.80
2.2
>
R
0.77
1.02
0.91
1.17
6.20
> 0.80
1.00
2.00
0.85
3.00
> 2.20
> 1.20
> 1.35
2.20
2.60
0.91
0.96
0.60
1.14
0.88
1.18
0.95
1.02
0.96
1.19
1.44
1.10
2.00
2.30
> 0.60
3.00
1.08
1.11
0.88
1.00
1.28
>
3.30
> 0.95
1.30
1.70
> 2.00
> 1.80
1.00
> 3.70
1.08
0.98
0.82
1.14
1.00
1.04
1.08
0.93
Substance
CAS#
FP °C
decalin
91-17-8
57
decane
124-18-5
46
diacetone alcohol
123-42-2
56
1,2-dichlorobenzene
95-50-1
65
dichloroethane /
1,2-dichloroethylene
107-06-2
13
diisobutyl ketone / DIBK
108-83-8
49
(dimethylamino) acetonitrile
926-64-7
36
dimethyl acetamide
127-19-5
70
dimethyl adipate
627-93-0
107
dimethyl ether
115-10-6
-41
dimethyl formamide
68-12-2
58
dimethyl glutarate
1119-40-0
103
dimethyl succinate
106-65-0
85
dimethyl sulfide
75-18-3
dimethyl sulfoxide
67-68-5
95
dipropylene glycol methyl ether
acetate
88917-22-0
86
1,4-dioxane
123-91-1
12
1,3-dioxolane
646-06-6
2
dodecane
112-40-3
71
ethane
74-84-0
-135
ethanol /
ethyl alcohol (*)
64-17-5
17
1-ethoxy -2-propyl acetate
54839-24-6
42
1-ethoxy-2-propanol
1569-02-4
42
2-ethoxyethylacetate
111-15-9
52
ethyl acetate (*)
141-78-6
-4
ethyl acrylate
140-88-5
9
ethyl benzene
100-41-4
27
ethyl chloroformate
541-41-3
16
55
CALIBRATION
LFLR
> 1.90
1.05
0.88
1.50
1.19
> 2.30
6.20
>
>
>
>
>
>
>
>
>
>
>
>
>
R
1.10
0.92
0.90
0.71
0.88
1.00
1.16
1.10
0.86
1.75
0.90
n/a
18.00
2.30
1.80
1.00
1.10
1.20
4.00
4.30
1.10
1.80
1.80
1.00
0.70
0.70
0.60
0.60
0.80
1.50
1.80
2.20
0.90
0.89
1.37
0.96
1.02
1.00
1.11
0.72
1.02
0.91
1.14
1.08
1.00
0.80
0.81
1.07
0.94
0.94
1.04
0.98
0.99
56
Corp.
Substance
ethyl ether
ethyl-3-ethoxypropionate
2-ethyl hexanol
ethyl L-lactate
1-ethyl-2-pyrrolidinone (NEP)
ethylene (*)
ethylene dichloride
ethylene glycol monobutyl ether
2-butoxyethanol
ethylene glycol monoethyl ether
ethyl cellosolve
formaldehyde and methanol
aqueous
formic acid
furan
furfural alcohol
heptane (*)
hexane (*)
1-hexene
hydrogen
hydrogen sulfide
isoamyl acetate
isobutane
isobutylene
isooctane
Isopar G
Isopar H
Isopar K
Isopar M
isophorone
isoprene
isopropyl acetate
isopropyl alcohol
CAS#
60-29-7
763-69-9
104-76-7
687-47-8
2687-91-4
74-585-1
107-06-2
FP °C
-45
58
81
49
76
-135
13
111-76-2
60
LFLR
> 1.40
4.40
> 6.00
1.30
> 1.20
2.7
> 1.00
1.20
8.10
110-80-5
43
>
64-18-6
110-00-9
98-00-0
142-82-5
110-54-3
592-41-6
1333-74-0
7783-06-4
123-92-2
75-28-5
115-11-7
540-84-1
64742-48-9
90622-57-4
64742-48-9
64742-47-8
78-59-1
78-79-5
108-21-4
67-63-0
60
69
-35
75
-4
-22
-25
25
-88
-76
-12
104
49
50
71
84
-53
2
12
12.00 1.10
1.00 1.19
>
1.80
4.00
> 1.20
1.20
2.30
2.50
>
R
1.02
1.20
1.06
0.88
0.98
1.02
1.10
0.82
1.41
1.01
0.81
0.98
1.09
0.98
1.39
1.60
0.80
0.80
0.90
4.90
0.90
2.60
0.90
0.94
0.92
1.00
1.11
1.07
1.04
1.30
0.70
2.40
1.60
> 0.80
0.93
0.71
1.17
1.22
1.00
>
>
>
>
>
>
Substance
isopropyl ether
methane
methanol
1-methoxy-2-propylacetate
2-methoxyethylamine
methyl acrylate
methyl amyl ketone
2-methyl-2-butanol
methyl chloride / chloromethane
methylene chloride /
dichloromethane
3-methylheptane, 95%
methyl ethyl ketone /
MEK / 2-butanone (*)
methyl formate
methyl isobutyl ketone / MIBK
2-methylpentane
methyl methacrylate
methyl proprionate
methyl tert-butyl ether
MTBE
mineral spirits RM-19
mineral spirits Shell 140
mineral spirits Varsol
monomethylamine
naptha, vm&p regular
nitropropane
n-methyl pyrrolidone
NMP
octene
2,4-pentanedione
3-pentanone, 99%
pinene
CAS#
108-20-3
74-82-8
67-56-1
108-65-6
109-85-3
96-33-3
110-43-0
75-85-4
74-87-3
FP °C
-18
-188
12
43
12
-3
39
21
0
75-09-2
589-81-1
7
78-93-3
107-31-3
108-10-1
107-83-5
80-62-6
554-12-1
-7
-19
17
-12
13
1634-04-4
8052-41-3
74-89-5
8032-32-4
79-46-9
-40
872-50-4
25377-83-7
123-54-6
96-22-0
-
93
21
34
13
32
Control
60
40
-18
20
33
Instruments
CALIBRATION
LFLR
1.70
1.30
1.80
2.20
2.00
2.40
> 2.20
>
>
>
>
>
>
R
0.93
0.96
0.96
0.99
1.04
0.93
0.97
1.60
0.90
1.3
> 1.70
0.60
> 1.80
2.35
> 0.43
> 2.00
> 1.20
7.00
8.00
> 0.47
> 1.20
1.40
2.00
> 0.80
> 0.58
3.00
> 1.10
0.89
0.94
0.93
1.02
1.19
0.95
0.94
1.03
2.09
1.66
1.03
1.00
0.79
2.29
1.00
1.05
1.01
1.04
Substance
propane
proprionic anhydride
propyl acetate
propyl alcohol / propanol (*)
propylene
propylene carbonate
propylene glycol
propylene glycol mono methyl
ether / PGME
propylene glycol mono methyl
ether acetate
pyridine
Shellsol T
styrene
tert-butyl alcohol
tetradecane
tetrahydrofuran
toluene / toluol (*)
trichloroethane
trichloroethylene
tridecane
triethylamine
trimethyl orthoformate
trimethylamine
turpentine
undecane
vinyl acetate
xylene / xylol (*)
PrevEx®InstructionManual
CAS#
74-98-6
123-62-6
109-60-4
71-23-8
115-07-1
108-32-7
57-55-6
FP °C
-104
63
14
15
-108
135
99
107-98-2
32
108-65-6
110-86-1
90622-57-4
100-42-5
75-65-0
629-59-4
109-99-9
108-88-3
71-55-6
79-01-6
629-50-5
121-44-8
149-73-5
121-44-8
8006-64-2
1120-21-4
108-05-4
1330-20-7
43
17
56
31
4
100
-14
4
79
16
15
<3
95
61
-8
27
57
CALIBRATION
7.2.
Recalibration Procedure
To be performed by qualified persons only. Perform at routine intervals as part of normal maintenance. If
changes to the types of flammable gases, the span calibration gas, the process temperature, or process
controls have been made, the initial calibration procedure in section 7.1 should be repeated.
WARNING!
During calibration, the analyzer alarms are bypassed. Calibration should only be
performed when it cannot interfere with the safe operation of the process being
monitored.
Verify normal operation. The calibration will not proceed if any fault except DOWNSCALE exists. If a
fault occurs during calibration, the calibration process will terminate. Make sure the temperature is stable,
with the insulating covers in place, for at least twenty minutes before starting. Accuracy is maintained
over a range of temperatures spanning not more than 50C (122°F). Therefore, where the analyzer is to be
exposed to changing temperatures in excess of this range, the accuracy must be restored by recalibration.
to allow calibration.
Record the RAW ZERO, RAW SPAN and CAL RDNG registers in the CAL MENU.
Open the Zero and Span Gas23 supply valves. Verify that the pressure is 20 ±1 PSIG.
Use the FULL CAL command to initiate calibration. Then observe:
UNLOCK
The ZERO solenoid valve is energized and the ZERO indicator comes on. Zero air enters the flame cell
from the zero inlet. The ZERO remains on for the CAL TIME setting in minutes.
ZERO ends. If the FLAME temperature is unacceptable (below 450°C or above 550°C), a ZERO FAIL
fault is activated and calibration terminates.
If the FLAME temperature is acceptable, it is taken as the RAW ZERO, which causes the reading to
display 0%LFL for a few seconds.
The SPAN solenoid valve is energized and the SPAN indicator comes on. Span calibration gas enters the
flame cell from the span inlet.
The SPAN remains on for the CAL TIME setting in minutes. The reading during the SPAN phase should
quickly come close to the CAL RDNG setting.
Observe the FLOW in the GAUGES menu. It will be compared to the sample FLOW after calibration to make
sure the calibration was valid.
At the end of the SPAN phase, if the FLAME temperature is unacceptable, a SPAN FAIL fault is activated
and the calibration process terminates.
If the FLAME temperature during the SPAN was acceptable, FLAME minus RAW ZERO is taken as the
RAW SPAN, which causes the reading to display the CAL RDNG for a few seconds.
The ZERO valve is turned on for one half the CAL TIME to purge out the span gas.
After the calibration ends the alarms are enabled.
If the RAW ZERO or the RAW SPAN values have drifted, a CHK ZERO or CHK SPAN message, and
the fault indicator, will appear intermittently. The SERVICE NEEDED relay activates. Refer to section
9.3 for a description of SERVICE NEEDED messages.
Record the new RAW ZERO and RAW SPAN and compare them to the old values. Investigate any
significant changes. Verify that CHK ZERO, CHK SPAN, ZERO FAIL or SPAN FAIL did not occur.
Compare the FLOW while sampling with the FLOW observed during span calibration. If they are not
the same, service the flow system (see maintenance section 9.12), and repeat the calibration.
Turn off the Zero Gas and Span Gas supply valves.
LOCK to secure from unauthorized or unintentional calibrations.
23
Before using a new cylinder of calibration gas, its contents should be analyzed to ensure the correct gas type and
concentration. Observe the first calibration with a new calibration cylinder carefully to verify the gas type and concentration.
58
Control Instruments Corp.
OPERATION
8.
Operation
Operators must read and understand this instruction manual. They must understand that the device is
for early warning of a potential fire or explosion. They must understand the meaning of the readings
and alarms. Alarm relays should be hard wired to the safety shutdown system as part of the overall
system design and in conformance to all applicable safety codes. They must not tamper with, or
otherwise defeat the intended protection of the alarms and relays.
Calibration, testing, maintenance and repair are beyond the scope of the operating instructions and
are to be performed by qualified persons only.
WARNING! Only the ACKNOWLEDGE and RESET controls should be accessible during operation.
8.1.
Reading and status.
Operators should be alert to abnormal readings or changes in the alarm indicators. Familiarity with
the normal range of readings under various process conditions will help operators detect abnormally
high or low readings. Unusually low readings might indicate analyzer failure that must be corrected
immediately. Unusually high readings might indicate the beginning of a serious problem with the
atmosphere or process. All alarms, service needed messages, and abnormal reading should be
recorded in a log and reported for correction.
WARNING! During alarms, the area near the analyzer may be explosive: keep a safe distance until the
cause has been found and corrected.
Install remote indicators, and acknowledge and reset controls, in a safe location where operators can
easily view the %LFL reading and the alarm status, preferably near a main control panel.
8.2.
Acknowledge Command.
The acknowledge command has two uses. It deactivates the horn relay. It also deactivates the service
needed relay. Acknowledge alarms first. Then investigate and correct the cause before attempting to
reset the alarm.
8.2.1.
How to acknowledge the Horn
When an alarm first occurs, the red ALARM LED flashes, and the HORN relay activates. As a
convenience to the operator, the HORN relay is deactivated by pressing either the MENU or SELECT
pushbutton. The ACKNWLDG command from the COMMANDS menu may also be used. Or the photo
transducer command ACKNWLDG can also be used.
For WARNING and DANGER alarms, use the remote acknowledge control to safely acknowledge the
alarm from a distance. See section 4.13.
Press the SELECT button. This will acknowledge the alarm and ―silence‖ the HORN relay. The
red ALARM indicator stops flashing. This method does not affect SERVICE NEEDED messages.
8.2.2.
How to acknowledge the SERVICE NEEDED message
Before acknowledging, record the Service Needed message.
Press the MENU pushbutton until the word COMMANDS appears in the display. Press SELECT.
Press the MENU button until ACKNWLDG appears. With ACKNWLDG in the display, press the
SELECT button. The display will flash for a few moments as the command executes. Wait for the
flashing to stop. This will deactivate SERVICE NEEDED messages, except CHK RDNG, which is
active whenever the reading is below -7%.
Or, shine a flashlight on the center phototransducer while covering the two outer
phototransducers. Remove the light when the ACKNWLDG command appears on the display. The
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OPERATION
display will flash for a few seconds, and then stop. It will acknowledge the alarm and ―silence‖
the HORN relay. The red ALARM indicator stops flashing. It will also deactivate SERVICE NEEDED
messages, except CHK RDNG, which is active whenever the reading is below -7%.
SERVICE NEEDED messages activate about half way towards the point of a fault. Left uncorrected, it
is likely that a fault will occur. SERVICE NEEDED messages give maintenance personnel the chance
to correct problems before they disrupt the operation of the analyzer. Acknowledging the SERVICE
NEEDED message does not correct the problem. After acknowledging the service needed message,
perform maintenance to prevent a future fault.
Acknowledging the CHK FLOW message means that another CHK FLOW message can occur when
the flow rate drops even closer to causing a LOW FLOW fault.
Acknowledging CHK ZERO or CHK SPAN clears them until another calibration is performed.
Acknowledging a CHK DATA message clears it. It means that all settings should be checked.
CHK RDNG means that the reading has drifted downscale. Recalibration may be needed. The CHK
RDNG message will not clear unless the reading rises back up towards 0%LFL.
8.3.
Reset Command
Alarms typically latch. They stay active until a reset command is performed. The RESET command
clears latched alarms if the condition that caused the alarm is no longer valid.
8.3.1.
How to reset alarms
Before resetting, make a record of the alarm, record the PEAK HI and PEAK LO readings, and
investigate to determine the cause of the alarm.
Press the MENU pushbutton until COMMANDS appears in the display. Press SELECT. Press the
MENU button until RESET appears. With RESET in the display, press the SELECT button. The
display will flash for a few moments as the command executes. Wait for the flashing to stop.
Or, shine a flashlight on the center phototransducer while covering the two outer
phototransducers. Remove the light when the RESET command appears on the display. The
display will flash for a few seconds, and then stop.
If the RESET is successful, the red ALARM indicator will go out, and the corresponding relay will
deactivate. If RESET is unsuccessful, the alarm will re-activate.
8.3.2.
Reset the danger alarm.
DANGER
alarms should only be reset after all corrective actions have been successfully completed.
Flooding of the flame cell with explosive concentrations can extinguish the sensing flame. If reset of
a DANGER alarm results in a FLAMEOUT fault, this could indicate a flammable concentration,
especially if the sensing flame cannot be re-ignited.
8.3.3.
Reset the flameout fault - Reignition.
A FLAMEOUT may require two RESET commands. The first re-ignites the sensing flame, and after a
minute or so, a second RESET clears the FLAMEOUT fault after successful ignition. If RESET of a
DANGER alarm results in a FLAMEOUT fault, this could indicate a flammable concentration,
especially if the sensing flame cannot be re-ignited.
WARNING! Flameout may indicate the presence of an explosive atmosphere.
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9.
Maintenance
In addition to the operator instructions and calibration, the following maintenance procedures are to
be performed semi-annually or as experience indicates they are required.
9.1.
General information and precautions
The following general precautions, and all warnings noted in this manual, must be
observed during all operation and maintenance procedures.
WARNING! Do not perform service when flammable gas might be present, or when servicing might
interfere with the safety and operation of the process or atmosphere being monitored.
WARNING!
WARNING!
The analyzer uses hydrogen or propane fuel. Observe all proper precautions for handling
compressed gases and flammable gases, including:
1. Turn fuel supply off whenever the air pressure is off. If necessary, an external automatic fuel
shutoff should be installed.
2. Eliminate ALL fuel fitting leaks. Use a leak-check (soap) solution, or a leak detector that is
sensitive to the particular fuel in use.
3. The sensor enclosure is sealed for purging. Air pressure must be maintained whenever fuel is
present to prevent an accumulation of flammable gas.
4. All covers must be kept tight whenever circuits are energized.
5. The fuel inlet fitting has a sintered metal restrictor that limits incoming fuel flow. Do not remove
the restrictor. Replace with a new restrictor fitting if clogged or damaged.
6. Keep sampling system clean and leak-tight. Check for leaks after all maintenance work.
7. Non-incendive circuits are used to prevent ignition of fuel leaks, sample leaks, or of the external
atmosphere. Do not modify the analyzer circuits, or add ignition-capable devices to the analyzer.
WARNING! The analyzer is electrically heated. Observe proper precautions for working with
electricity and hot surfaces, including:
8. Prevent electric shock. Turn off electrical power before performing maintenance.
9. Prevent burns from contact with the heated flame cell components. Use insulated gloves. If
necessary allow parts to cool just enough to allow maintenance.
10. Prevent overheating of the flame cell. Always keep the insulated flame cell cover in place during
operation.
WARNING! The analyzer has a low-power high-voltage ignition transformer. When operating the
controller with the ignition cable detached, attach a shorting clip from the ignition cable connection
of the controller to the chassis ground.
WARNING! The sensor uses inlet and exhaust flame arrestors to protect the atmosphere being
monitored. Observe precautions for hazardous locations, including:
11. Keep flame arrestors clean and installed at all times.
12. Flameproof joints and threads must be kept clean and free from any mechanical damage that can
degrade the protection they provide.
13. Replace any components that show mechanical deformation, abrasion, or damage to the
flameproof joints, threads or surfaces.
14. Test alarms regularly.
WARNING! Analyzers monitoring pressurized or hazardous atmospheres should not be disassembled
until the atmosphere being monitored is safe and free of excess pressure, hazardous gases, or other
substances or conditions that may be released during maintenance.
15. Make a record of analyzer maintenance. Use the form in section 9.2, or equal.
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Aspirator
PLUG, 1/4NPT
SPRING, SPR013
SPACER, SPC009
NOZZLE, NZL001
Flame Cell
O-Ring ORG044 (Viton)
or ORK046 (Kalrez)
O-Ring ORG041 (Viton)
or ORK047 (Kalrez)
Orifice and Filter
Orifice ORF024
Filter FLT087
Filter FLT012
Flame Arrestor SNP189
Arrestor Cap SNP188, with O-Ring
ORG005 (Viton) or ORK005 (Kalrez)
Filters and Flame Arrestors
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9.2.
Analyzer Maintenance Record
Name
Date
Equipment Serial Number
Time
Location
Tag# / ID#
DESCRIPTION(S):
STARTUP
CALIBRATION
PREVENTATIVE MAINTENANCE
TESTING
REPAIR
LEAK CHECK
FILTER CHANGE
O-RING CHANGE
CLEANING
ALARM TEST
OTHER/DETAILS:
Record of values from PrevEx controller. If value has changed, mark “as found” and “as left”
GAUGES
CAL MENU
ALARMS
OUTPUTS
COM PORT
READING
RAW ZERO
WARNING
RLY TEST
SET BAUD
STATUS
RAW SPAN
DANGER
MA TEST
BAUD RATE
PEAK HI
CAL TIME
LATCHES
4MA ADJ
AUTO BAUD
PEAK LOW
CAL RDNG
FAIL SAFE
20MA ADJ
ADDRESS
HSG TEMP
SPAN DEG. C
VERSION
MA CAL
IDNBR
SET TEMP
SPEED
TYPE
MA FAULT
SERIAL
CONTROL 1
FLOW
LOW FLOW
CONTROL 2
CHK FLOW
RLY CONFIG
FLAME
Record the state of the indicators:
OFF=
ON=
FLASHING=
Alarm
Scan
Fault
Danger
Warning
Horn
Zero
Span
Ignite
Heat
Utility
Measurement
“As found” /
“As left”
Units
Fuel inlet
PSIG
BAR
Zero inlet
PSIG
BAR
Notes
Span inlet
PSIG
BAR
Compressed air
PSIG
BAR
Measure the pressure of each
inlet and check off units. Show
measurement as found prior to
service, and as left after
adjustment, if any.
Air dilution inlet
PSIG
BAR
If unused, this must be capped
Span cal gas
1.15% Ethylene in air +/-0.02
Other:
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Identify type and concentration,
including analysis / tolerance.
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9.3.
“Service Needed” Messages
When a condition exists that might lead to a fault, the SERVICE NEEDED relay activates. If there is no
alarm at the time, a message is displayed, and the yellow FAULT indicator blinks. The ACKNWLDG
command deactivates the Service Needed relay and message, but does not fix the problem.
9.3.1.
SERVICE NEEDED - CHK FLOW
– Check sample flow rate
A sample flow rate more than half way towards LOW FLOW for more than fifteen seconds displays a
CHK FLOW message. The ACKNWLDG command moves the level at which the next CHK FLOW
message will be given to a level half way between the present flow rate and the LOW FLOW level. If
the flow continues to fall, eventually another CHK FLOW message should occur. Without
maintenance, a LOW FLOW fault can occur.
1. Record the FLOW rate from the GAUGES menu.
2. At the earliest convenient time, ACKNWLDG the message and troubleshoot the flow system to
isolate the problem to the air pressure, sample tubing, filters, o-rings, orifice, or aspirator.
3. Verify that the FLOW has been restored +0.5 LPM or more above the LOW FLOW level.
4. After correcting the problem, use the RESET command. It will adjust the level at which CHK
FLOW is given half way back up towards the present flow rate.
If CHK FLOW "service needed" message is active, the ACKNOWLEDGE command level will
move CHK_FLOW downwards half way between FLOW and the LOW FLOW level, but only if the
result would be a lower CHK_FLOW level. The RESET command will move CHK_FLOW to a
level half way between the present FLOW rate and the LOW_FLOW level, but only if the result
would be an increase in the CHK_FLOW level.
The LOW FLOW level can be adjusted using the GAUGES menu. Normally, the default value of 1.4
liters per minute is acceptable and should not be changed. Higher settings can be used to give earlier
warning of a loss of flow, and are recommended where possible. Accuracy is maintained over a
range of sample flow rates that varies less than +/-0.3 liters per minute from the flow rate during
calibration. The LOW FLOW setting should be set to give a SERVICE NEEDED indication or a FAULT
indication if the flow rate decreases more than this amount below the flow rate during calibration.
9.3.2.
SERVICE NEEDED - CHK RDNG
– Check downscale reading
If the reading is below -7%LFL for more than fifteen seconds, a CHK RDNG message is given and the
relay is activated. The Acknowledge command does not clear this message until
the reading goes above -7%LFL. If the drift is not corrected, a DOWNSCALE FAULT will occur below
-10%LFL.
SERVICE NEEDED
1.
2.
3.
4.
Immediately verify that the fuel supply pressure is above the minimum and is not running out.
Record the FLAME temperature from the GAUGES menu.
At the earliest convenient time, recalibrate the analyzer.
If the calibration fails, or if a CHK ZERO message occurs after calibration, readjust the fuel
regulator to get a FLAME temperature of 500°C.
5. After correcting the problem, use the ACKNWLDG command to clear the SERVICE NEEDED
message.
6. If the fuel regulator has been adjusted, recalibrate the analyzer.
7. Check for leaks in the fuel system. Tighten the fuel fitting located at the side of the flame cell.
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9.3.3.
SERVICE NEEDED
- CHK ZERO - Check zero calibration
If the flame temperature during zero calibration is less than 475 °C, or greater than 525 °C, the CHK
ZERO message is given and the SERVICE NEEDED relay is activated. Although the calibration is
acceptable, the zero has drifted from the ideal value, and eventually might need readjustment of the
fuel regulator pressure. If the drift continues, the FLAME temperature may go below 450 °C and
activate a FLAMEOUT fault. Attempting to zero calibrate with the FLAME temperature below 450°C or
above 550°C will give a ZERO FAIL fault.
1. Immediately verify that the fuel supply pressure is above the minimum and the fuel supply is not
running out.
2. Immediately verify that the air pressure to the zero calibration inlet is correct.
3. Record the RAW ZERO temperature from the CAL MENU.
4. At the earliest convenient time, ACKNWLDG the message, and adjust the fuel regulator for a
FLAME temperature of 500°C per section 9.14.
5. Recalibrate the sensor and verify that the RAW ZERO is near 500°C.
The expected rate of drift in the RAW ZERO is less than 25°C per year. Higher rates may indicate a
problem with the fuel regulator, or the fuel itself.
9.3.4.
SERVICE NEEDED
- CHK SPAN Check span calibration
During span calibration, the difference between the FLAME temperature and the RAW ZERO is the
RAW SPAN. This is the temperature rise above zero caused by the test gas. The RAW SPAN
temperature rise is tested against the expected temperature rise in the register SPAN °C. There are
three possibilities:
1. RAW SPAN is within ±12.5% of SPAN °C
2. RAW SPAN outside ± 12.5%, within ± 25%
3. RAW SPAN outside ± 25% of SPAN °C
Calibration is successful.
Calibration is successful, but a CHK SPAN
message given
Calibration fails, RAW SPAN not updated, old
calibration is restored, SPAN FAIL fault is
given, and a CHK SPAN message is given.
For the standard test gas, 1.15% by volume Ethylene in Air, the expected temperature rise is
approximately 125°C (60°C in air dilution types). A few degrees variation can occur due to slight
mechanical differences between individual analyzers. A 5°C to 10°C effect can come from the effect
of the HSG TEMP. A higher operating temperature means a slightly lower RAW SPAN.
Using the standard calibration span gas, the SPAN °C should never require readjustment.
1.
2.
3.
4.
Record the RAW SPAN temperature from the CAL MENU.
Immediately verify the concentration and type of the calibration span gas.
At the earliest convenient time, ACKNWLDG the message, and service the flow system.
Recalibrate the sensor and verify that the RAW ZERO is near 500°C.
Use the ACKNOWLEDGE command to clear the message and relay. Record the RAW SPAN value from the
GAUGES menu. At the earliest convenient time, check the span gas supply and pressure, the
thermocouple cleanliness, and check the analyzer for leaks. Following service, recalibrate the
analyzer.
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9.3.5.
SERVICE NEEDED - CHK DATA Check
for data loss
Settings are stored in RAM memory and are also saved in EEPROM. When power is turned off, the
settings in RAM are lost but the settings in EEPROM are preserved. When power is turned on, the
settings are copied from EEPROM into RAM. When a setting is changed intentionally through a
menu or through the serial port, it is changed first in RAM and then is copied to EEPROM within
one minute. During operation, the settings in RAM are tested continuously to make sure that they
stay within acceptable limits, and that they match the settings stored in EEPROM. This helps prevent
an unintentional change in a setting in RAM from a momentary fault or power interruption.
If the controller‘s self-diagnostics detects a discrepancy in a setting, the CHK DATA message is given,
and the SERVICE NEEDED relay is activated. The CHK DATA message means that there may have been
an unintentional change in a setting. It is necessary to verify that the settings are correct.
Use the ACKNOWLEDGE command to clear the message and relay. Review all settings in the CAL
MENU, ALARMS, OUTPUTS and COM PORT menus. If RAW ZERO or RAW SPAN settings are incorrect
or have changed, recalibrate the analyzer. If this message is given repeatedly, investigate the
analyzer power supply for power disturbances. Verify that the ignition spark discharges to the tip of
the burner, and that the gap between the ignition electrode and burner tip is correct. If the problem
remains, it is likely the EEPROM or RAM in the controller has a fault that requires factory repair.
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9.4.
Scheduled Maintenance
There is a wide variety of applications, industry codes, and operating conditions. Base the
maintenance schedule on both design and experience. The initial maintenance schedule shown below
should be adapted as needed.
Procedure
Section Frequency
Readings
9.5
Daily
Utilities
9.6
Weekly or monthy
Gauges
9.7
Monthly or quarterly
Recalibration
9.8
Monthly
Leak test
9.9
After any disassembly. Otherwise quarterly or yearly.
Alarm test
9.10
Monthly. Yearly is minimum required by code.
System review
9.11
Semi-annual or when process or monitoring conditions
change.
Flow system
9.12
Quarterly or yearly
For CHK FLOW, or LOW FLOW status
Cleaning
9.13
As needed for CHK FLOW, or LOW FLOW status
following flow system maintenance
Fuel regulator
9.14
Yearly, or for CHK ZERO or ZERO FAIL status
More frequent adjustment should not be required.
9.5.
Readings
Readings should be checked frequently. Operators should have access to a display of the reading
near the control panel or operator station used to control or monitor the process or atmosphere being
monitored. Abnormally low readings are as important as abnormally high readings, and should be
investigated. They might indicate an analyzer leak, or another fault that the analyzer itself is unable
to detect.
The PEAK HI and PEAK LOW readings can help with understanding the normal range of readings.
Knowing the normal range of readings for a particular process or set of conditions can help identify a
problem well before it might become a hazard. PEAK HI and PEAK LOW are cleared by the RESET
command.
Knowledge of the normal range of readings helps set the alarm levels properly. The lowest WARNING
and DANGER alarm levels that do not produce false alarms are the best. Information gathered over
time can be used during the annual review to help choose the best alarm levels.
9.6.
Utilities
Keep all utilities, power, air and fuel, on continuously, so that the analyzer gives the best
performance and requires the least maintenance. On regular intervals, verify the air pressure. The air
supply likely has a filter that might require cleaning or replacement. If it is necessary to adjust the air
pressure, check the air supply filter. Check the fuel pressure, and the quantity of fuel remaining in
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MAINTENANCE
the supply, often enough that the fuel cannot lose pressure or unexpectedly run out. Before and after
calibration, check the supply of calibration gas and reorder if necessary.
9.7.
Gauges
Make an analyzer maintenance record (see section 9.2) at regular intervals, especially before and
after calibration or maintenance. Investigate significant changes, especially in FLOW, RAW ZERO and
RAW SPAN.
The FLOW rate on the GAUGES menu should not change by more than a few tenths of a liter per
minute per week. The FLOW rate observed during startup, when the analyzer was first put into
service in clean condition, is a good reference point. Reduced flow rates indicate need for filter
changes. Inability to restore flow near its startup value indicates the need for cleaning.
The HSG TEMP should be stable to within +/- 3°C of the SET TEMP value.
The FLAME temperature, measured as RAW ZERO and RAW SPAN in the CAL MENU, should also be
stable to within several °C before and after calibration. The CHK ZERO and CHK SPAN messages help
identify significant changes.
9.8.
Recalibration
Calibrations and tests using known gas concentrations should be performed regularly. This is the best
way to verify proper operation. Operating history will determine frequency of calibrations. Zero and
Span tests can be performed to verify correct response and help determine the most appropriate
calibration schedule. Some codes, for example NFPA-86 Ovens and Dryers, require a monthly
calibration to verify proper sensor response.
9.9.
Leak test
The analyzer can not detect some types of leaks in the sampling system that might dilute the sample
and cause false low readings. A leak test should be performed regularly. It should also be performed
after maintenance involving disassembly of any part of the sampling system.
1.
2.
3.
4.
5.
Use the GAUGES menu to display FLOW .
Remove the sample probe fitting at the analyzer inlet.
Cap off or otherwise block the analyzer sample inlet.
For air dilution types, turn off pressure and block flow to the dilution air inlet B.
Verify that the FLOW drops below 0.01 LPM.
9.10.
Alarm test
The alarm relays are used for corrective action. Immediate and effective corrective action is needed
to prevent the possibility of a fire or explosion. At regular intervals, perform a complete test of the
relays and the corrective action.
1.
2.
3.
4.
5.
Verify that WARNING and DANGER levels in ALARMS menu are correct.
Use RLY TEST in OUTPUTS menu to activate relays.
Verify that actions of each relay produce the desired overall result.
Verify that the DANGER relay activates the safety shutdown.
Verify that the FAULT relay activates the safety shutdown.
9.11.
System review
Semi-annually, or when process or monitoring conditions are changed, review the initial calibration
information to ensure that the calibration remains valid, check maintenance records for potential
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problems and adjust the maintenance schedule as needed, and refresh training and education of
operators and maintenance personnel. Some codes require an annual review by a factory-trained
technician. Leak test failures and in some cases calibration failures or calibration check alarms may
be an indication of an o-ring failure.
Unless guided elsewhere in this manual the table below indicates the expected life of the o-rings by
model number and operating temperature.
Model #
SET
TEMP
Flame arrestor end caps orings
Interblock o-rings
SNR671
60°C
ORG005 – 5 year replacement
ORG041, ORG044 – 5 year replacement
SNR672
120°C
ORG005 – 5 year replacement
ORG041, ORG044 – 5 year replacement
SNR674
200°C
ORG005 – 1 year replacement
ORG041, ORG044 – 1 year replacement
SNR675
250°C
ORK005 – 6 month replacement
ORK046, ORK047 – 1 year replacement
Over time the air purge restrictor on the manifold can be clogged with oil, water or debris from the
compressed air supply to the analyzer. A clogged restrictor will not supply fresh air into the analyzer
housing sweeping out any potential leaking fuel that may be present. Semi-annual checks of this
restrictor can be easily done by placing a finger tip over the restrictor and listening/feeling for air
escaping around your finger. If little or no air is detected the restrictor should be replaced with the
instructions and part of an SRV153.
Photo 1
Remove the outer cover of the analyzer when it is safe to do so.
Locate the air purge restrictor on the manifold and test it for flow with your finger as shown in
Photo 1. If air flow is low or not detected replace restrictor with SRV153.
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9.12.
Flow System Preventative Maintenance
Routine replacement of the disposable filter elements, and where needed, cleaning of flame arrestors,
prevents loss of sample flow. Replacement of O-rings helps prevent leaks.
SNR671, SNR672 and SNR674 use Viton O-rings. These have good temperature and solvent
resistance, and are inexpensive. They can be used up to 200°C. They should be replaced whenever
they are disassembled during a service procedure. O-rings in SNR675 are Kalrez®. These are
required for flame cell temperatures above 200°C. They are expensive, but have superior heat and
solvent resistance, and so can be re-used if they are not damaged, deformed or shrunken. If the Oring is elastic, has a uniform cross-section, has no abrasion, breaks or cuts, and no signs of shrinking
or hardening, it can be re-used. When in doubt, replace the o-ring.
FILTER ELEMENT, FLT012, INSIDE
FLAME ARRESTOR, SNP189
O-RING ORG005 or ORK005
CAP SNP188
1. Remove outer cover.
2. Remove inner cover (except SNR671 types). Cover is retained by four mounting pins that fit into
keyhole-shaped slots on the cover. Lift cover straight up ¼ inch, until all four mounting pins line
up with slot openings, then slowly pull the cover straight out from flame cell. Do not force the
cover, or the mounting pins may be damaged.
3. Unscrew the flame arrestor caps located on the left side of the flame cell block.
4. Unscrew the flame arrestors from the flame cell.
5. Remove filter elements from inside the flame arrestor.
6. Clean the flame arrestor with compressed air. If necessary, soak the flame arrestor in solvent and
dry completely before reinstalling. Do not clean mechanically, such as by sanding or scraping
the surface. Abrasive cleaning will cause damage.
7. Insert replacement filter element (Part Number FLT012) into flame arrestors.
8. Screw flame arrestor clockwise into flame cell until hand-tight, then back out counterclockwise
1/8 of a turn. Do not over tighten.
9. Replace the o-rings on the flame arrestor caps. (Part Number ORG005, except for SNR675,
which uses ORK005 Kalrez O-rings to operate above 200°C).
10. Screw flame arrestor caps into flame cell until o-rings seal and cap is hand-tight.
Do not over tighten: The flame arrestor cap is sealed by the o-ring. When properly installed,
there is a 1/32‖ (0.8 mm) gap between the arrestor cap and the flame cell surface. About half the
O-ring width remains visible. Do not attempt to screw the arrestor cap completely into the flame
cell until it bottoms out, because this can damage the threads.
11. Perform a leak test. Plug the sample inlet. Verify FLOW on GAUGES menu below 0.01 LPM.
12. After temperature stabilizes, perform a full calibration.
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9.13.
Purpose
Cleaning
Restore sample flow by removing contamination on aspirator or orifice.
Increases aspirator suction, decreases flow resistance in orifice.
Returns sample FLOW reading on GAUGES menu to a normal level.
Frequency
As needed, if Flow System Preventative Maintenance does not restore sample flow,
and sample and exhaust tubing are not clogged.
Clean flame cell if an accumulation forms on the burner, the thermocouple or the
upper flame arrestors, causing a CHK ZERO or CHK SPAN message during calibration.
If a flow problem is not caused by a lack of air pressure, or a clog in the sample or exhaust tubing,
the filters, or the flame arrestors, then the problem might be due to a lack of suction from the
aspirator or a clog in the orifice. Over time, particles or condensate can accumulate. Some substances
in the sample, such as silicones, may form dust when burned in the sensing flame. This dust can
accumulate on the burner, thermocouple, or upper flame arrestor. The dust is removed to restore the
sample flow, or to restore the RAW ZERO and RAW SPAN to normal values.
9.13.1.
Aspirator cleaning or replacement
Parts Needed
Tool needed
Aspirator nozzle - if needed. Part number NZL001
Allen key. Needle nose pliers.
3/16 inch
1. Turn all utilities off.
PLUG, 1/4NPT
2. Using a hex key, remove the ¼ NPT plug from the top of the
heated block assembly. This is the middle plug on the top right
SPRING, SPR013
hand side of the flame cell.
SPACER, SPC009
3. Remove the spring and spacer.
NOZZLE, NZL001
4. Use needle-nose pliers to remove the aspirator nozzle. Be
careful not to damage the inside of the nozzle. If the nozzle is
difficult to remove, you can also remove the ¼ NPT plug from
the bottom of the block (directly below the aspirator) and use a
soft wooden stick to push the nozzle from its seat.
5. Clean the bore and nozzle with a solvent such as acetone or
alcohol, and let dry.
6. Replace nozzle with new if contamination cannot be removed.
7. Re-install the nozzle, spacer, and spring. Replace the ¼ NPT
plug(s).
8. Restore utilities.
9. Re-ignite the analyzer
10. Allow analyzer time to stabilize.
11. Perform a full calibration.
Oil or residue on the inside of the nozzle may indicate oil in the compressed air supply. Check the
compressed air supply filters and replace if necessary.
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9.13.2.
Orifice cleaning or replacement
Parts Needed
Tools needed
Orifice filter - if needed. Part number FLT087.
Orifice - if needed. Part number ORF024.
O-rings - if needed, quantity 1, part number ORG005 (Viton) or ORK005 (Kalrez)
Screwdriver
Locking screw driver- 10‖ quick wedge screwdriver, part number TOL044
1/8 inch Allen key (Part number TOL046 or equal)
1. Verify the compressed air pressure.
Insufficient air pressure causes
reduced flow that will not be
corrected by cleaning.
2. Turn all utilities off.
3. Remove upper flame arrestor cap.
PARTS CAN BE REMOVED
WITHOUT DISASSEMBLY
4. Remove upper flame arrestor.
OF BLOCKS.
5. Use locking screwdriver to remove
the orifice filter through the upper
ORIFICE FILTER FLT087
flame arrestor block opening.
6. Use Allen key to remove orifice.
ORIFICE ORF024
7. Clean the orifice and orifice filter
with a solvent such as acetone or
alcohol, and let dry. Do not drill out.
8. Replace orifice or orifice filter with
CUTAWAY VIEW OF ORIFICE AND FILTER INSIDE FLAME CELL.
ACCESS IS THROUGH UPPER FLAME ARRESTOR CAP.
new if contamination cannot be
removed.
9. Re-install the orifice.
10. Re-install the orifice filter.
13. Re-install filter and flame arrestor. Screw flame arrestor clockwise into flame cell until handtight, then back out counterclockwise 1/8 of a turn. Do not over tighten.
14. Check flame arrestor cap o-ring and replace if needed.
11. Re-install flame arrestor cap and o-ring. Do not over tighten: The flame arrestor cap is sealed by
the o-ring. When properly installed, there is a 1/32‖ (0.8 mm) gap between the arrestor cap and
the flame cell surface. About half the O-ring width remains visible. Do not screw the arrestor cap
completely into the flame cell until it bottoms out, it will damage the threads.
12. Restore utilities.
13. Re-ignite the analyzer.
14. Allow analyzer time to stabilize.
15. Perform leak check of sampling system.
16. Perform a full calibration.
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Control Instruments Corp.
MAINTENANCE
9.13.3.
Flame cell cleaning
Parts Needed
Tools needed
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Orifice filter - if needed. Part number FLT087.
Orifice - if needed. Part number ORF024.
O-rings - if needed:
Qty 1 of ORG044 (Viton) or ORK046 (Kalrez)
Qty 2 of ORG041 (Viton) or ORK047 (Kalrez)
Qty 2 of ORG005 (Viton) or ORK005 (Kalrez) GAP
Screwdriver
Locking screw driver- 10‖ quick wedge
screwdriver, part number TOL044
1/8 inch Allen key, part number TOL046 or equal.
5mm Allen key for flame cell bolts.
Alignment tool, part number TOL003 or TOL047.
1/4"
THERMOCOUPLE
BURNER
Turn all utilities off.
Remove sample probe.
Remove flame arrestor caps, and remove flame arrestors.
Use locking screwdriver to remove the orifice filter.
Remove eight flame cell bolts. For best results, loosen bolts while
blocks are warm.
Lift flame cell block straight out and away from burner plate, taking
care not to bend the thermocouple or burner.
Clean flame cell parts as needed.
Align the thermocouple, burner and spark electrode.
The thermocouple should be directly above the burner, with ¼ inch gap.
The spark electrode is located 1/10 inch (2.5mm) behind, and just
above, the rear of the burner. Use the alignment tool, part number
TOL003 or TOL047. Avoid excessive bending of the thermocouple,
which can cause damage.
Replace flame cell o-rings with new, if needed.
Re-install flame cell block, but do not bend the thermocouple or burner.
Re-install and tighten flame cell bolts.
Re-install the orifice filter.
Re-install filters and flame arrestors. Screw flame arrestor clockwise
into flame cell until hand-tight, then back out counterclockwise 1/8 of
a turn. Do not over tighten.
Check flame arrestor cap o-ring and replace if needed.
Re-install flame arrestor cap and o-ring. Do not over tighten: The
flame arrestor cap is sealed by the o-ring. Properly installed, there is a
1/32‖ (0.8 mm) gap between the arrestor cap and the flame cell
surface. Half the O-ring width remains visible. Do not attempt to
screw the arrestor cap completely into the flame cell until it bottoms
out, because this can damage the threads.
Restore utilities.
Re-ignite the analyzer
Allow analyzer time to stabilize.
Perform leak check of sampling system.
Perform a full calibration.
PrevEx®InstructionManual
73
MAINTENANCE
9.14.
Purpose
Fuel Regulator Adjustment
Adjust sensing flame until FLAME temperature on GAUGES menu is 500°C when no
flammable gases are present in the sample.
Frequency
Every twelve months
Following a CHK ZERO Service Needed Message, when RAW ZERO is below 475°C
or above 525°C
Following a ZERO FAIL fault, when FLAME is lit, but is below 450°C or above 550°C
during a zero test.
Parts Needed
Fuel inlet fitting, part number SNP374 - if needed.
The fuel regulator may exhibit a slow drift. Routine calibration will remove the error from this drift,
but eventually the drift can accumulate over time, and a CHK ZERO SERVICE NEEDED message, or
even a ZERO FAIL fault, might occur. Readjustment of the fuel regulator pressure can restore the
sensing flame to its optimal size.
The fuel pressure should be above the minimum required pressure at the inlet to the analyzer.
There is a small sintered metal filter installed inside the fuel inlet fitting. This filter protects the fuel
system from contamination. It should not normally require replacement if the fuel delivery system
and fuel tubing is clean and free of contamination. In some cases, a contaminated fuel restrictor must
be replaced in order to pass enough fuel through to the analyzer‘s sensing flame.
1. Verify that the flame cell temperature is stable. Variations in flame cell temperature can cause
drift in the flame temperature that will not be corrected by fuel regulator adjustment.
2. Verify that the fuel pressure at the inlet is correct. Incorrect fuel pressure can cause drift in the
flame temperature that will not be corrected by fuel regulator adjustment.
3. Check fuel purity. Impure fuels, or impurities in fuels that respond to temperature changes, will
not be corrected by fuel regulator adjustment.
4. Remove the outer enclosure cover. (Leave the insulated flame cell cover in place).
5. Lift the controller, slide the upper retaining pins from the
bracket, leave the lower retaining pins in place, and swing the
controller down to give access to the fuel regulator.
6. Loosen the lock nut on the fuel regulator adjustment screw.
7. Slowly turn the fuel regulator adjustment screw until the
FLAME temperature on the GAUGES menu is 500°C ± 5°C.
Turn the adjustment screw clockwise into the regulator to
increase FLAME, counterclockwise to decrease FLAME.
Increases occur quickly, but decreases occur
slowly. Do not over adjust when decreasing.
8. Tighten the lock nut on the fuel regulator
adjustment screw.
9. Re-install outer cover.
10. Perform a full calibration.
11. Test the regulation of the fuel system by increasing the fuel pressure at the analyzer inlet by a
few PSIG. The reading should not change. When finished, set fuel pressure to correct setting.
LOCK NUT
FUEL REGULATOR
ADJUSTMENT SCREW
FUEL INLET
FITTING SNP374
74
Control Instruments Corp.
TROUBLESHOOTING
10.
Troubleshooting
These requirements for proper operation are shown in their order of importance.
AC Power
All power and voltages for the analyzer‘s operation is derived from the AC power mains. Power
must be supplied continuously within +10%/-15% of the rated voltage.
10.1.
10.1.1.
Fuse replacement
Parts Needed
5 Amp, Part number FUS037, for power to controller and heater.
½ Amp, Part number FUS038, for controller power.
1. Disconnect electrical power at the power switch or circuit breaker.
2. Remove the outer cover.
3. The controller is mounted by four pins that fit into slots on a bracket.
Slide the controller up ¼ inch. Swing the top outwards so only the top
pins come out of their slots. The lower pins must remain in their slots.
4. The fuses are on the right side of the controller. Use a screwdriver to
turn the fuse holder cover counterclockwise 1/8th of a turn.
5. Remove and replace fuse with same rating and type as shown on label or fuse.
6. Re-mount the controller and replace the outer cover.
FUS037
FUS038
Flame Cell Temperature
The flame cell is heated by an AC-powered electric heater. Thermocouple TC2 in the flame cell
block measures the HSG TEMP temperature. Heating is controlled by SET TEMP. A deviation more
than a few degrees results in a fault. At startup, or after a change to the SET TEMP setting, a TEMP
LOW or TEMP HIGH fault exists until the flame cell reaches the new temperature. The time can vary
from 15 minutes at a SET TEMP of 60°C, to as much as 90 minutes at 250°C.
10.2.
The sensing flame requires a stable flame cell temperature. Temperature changes cause drift. Low
temperatures can also cause condensation, leading to false low readings, or clogging. Always keep
the flame cell heated and insulated with its covers in place. If power is to be turned off for some
time, the air pressure should be removed and the fuel should be turned off. In some cases the sample
and exhaust tubing must be capped as well.
The TC2 thermocouple is 0 millivolts at 0°C, and increases about +1 millivolt for every 25°C.
Air Inlet Pressure
Compressed air is used for suction to draw the sample into the flame cell. It also purges the enclosure
to prevent the accumulation of leaking fuel or flammable gases. The compressed air pressure must be
regulated to 20 PSIG (1.4 bar). Low or high air pressure causes flow faults.
10.3.
Fuel Inlet Pressure
The sensing flame uses hydrogen or propane fuel. Low fuel pressure causes downscale reading drift.
10.4.
External fuel line leaks not only waste fuel they can cause low fuel line pressure and analyzer
reading drift sufficient to cause a downscale fault to occur. Test for leaks by shutting off the fuel at
the tanks and watch the line pressure. Quick drops in pressure indicate fuel line leaks. A leak tight
system will hold pressure for minutes without a significant drop in pressure. Use a soap solution at
all fittings to locate possible leaks.
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TROUBLESHOOTING
Propane fuel should not be stored outdoors, exposed to large temperature changes. Low temperatures
cause low propane pressure. Large temperature changes increase the effect of impurities.
The fuel inlet fitting has a sintered metal filter inside. It prevents contamination from reaching the
analyzer. It also limits the fuel flow that can leak into the enclosure. A contaminated restrictor drops
the fuel pressure and causes low readings and reading drift. Tubing or fitting leaks in the analyzer
enclosure can cause the pressure to drop, resulting in low readings. Check internal fitting for leaks
especially the fuel fitting at the side of the flamecell.
Test the fuel restrictor and regulator. Attach a pressure gauge to the fuel inlet. Increase pressure by
+5 PSIG and observe the reading and FLAME measurement, it should remain the same. If the reading
changes more than 2%, it means the fuel system is not regulating properly, and the analyzer readings
will drift. Check for fuel leaks in the analyzer enclosure. Check or replace the fuel inlet fitting.
10.5.
Spark
The sensing flame is ignited by a two-second spark discharge from a small electrode mounted to the
spark plug in the flame cell to the grounded burner tube. The spark is generated by a high voltage (30
kV) transformer in the controller.
The spark electrode must be aligned about 1/10th inch (2.5mm) behind, and slightly above, the rear of
the burner tip. If the spark discharge strikes too low on the burner, the fuel will not ignite. If the
spark discharge is too close or too far from the burner it can cause the controller to reset itself.
10.6.
Flame
Flammable gases in the sample are burned in the sensing flame. This results in a temperature rise in
the TC1 thermocouple located above the sensing flame. The sensing flame must be stable. The fuel
supply pressure must be constant. The fuel, especially when propane is used, must be pure.
The TC1 thermocouple makes the FLAME temperature measurement. It must be properly aligned
above the sensing flame, at the correct distance. The sensitivity is about 0.5%LFL per degree C. Use
care when aligning the thermocouple. Excessive bending causes damage.
A propane sensing flame appears as a small round blue flame about the size of a match head. It may
have a small yellow tip at the top. Hydrogen flames are not visible to the human eye. Solvents and
other flammables burning in a hydrogen flame cause a faint blue glow. Explosive concentrations in
the flame cell can emit an orange or yellow burst of flame. Sometimes the TC1 thermocouple that
measures the FLAME temperature has a faint red glow when the flammability reading is high. A
bright red thermocouple indicates very high flammability.
10.7.
Sample Flow
The sample flow rate must be maintained to ensure that measurement is accurate and timely. If the
flow rate decreases the measurement will become slower, especially if the sample tubing is long.
The sample orifice is used to measure the FLOW . It must be kept clean so that the measurement is
accurate. In some cases, the orifice will require periodic cleaning. A sintered metal filter must be
removed using a flat head holding screwdriver to get access to the sample orifice. The sample orifice
can then be removed and cleaned.
A partially or completely clogged orifice may trigger a HI FLOW fault message. A partially clogged
orifice may result in slow response to sample and calibration gas, FLAMEOUT faults, inability to
ignite or stay lit after an ignition attempt or span calibration failure, SPANFAIL.
76
Control Instruments Corp.
TROUBLESHOOTING
10.8.
Calibration Flow
Zero gas must be clean, dry, instrument-grade air from a cylinder or properly filtered compressor.
Oil in unfiltered compressed air can be vaporized in a high temperature analyzer, burn in the sensing
flame, and cause a false zero reading.
Zero and span calibration gases are injected under 20 PSIG (1.4 bar) pressure through sintered metal
restrictors located inside the inlet fittings. Each restrictor must be kept clean and in place. If the
calibration flow is too low or too high, errors will occur. An excess of calibration flow must be free
to flow out of the sample tubing.
Fuel pressure must be steady, within specification, and not running low for a successful calibration.
Fuel line leaks that cause reading drift will be captured during calibrations resulting in reading error
until a proper calibration is done.
Positive reading shifts after a zero calibration (when no combustibles are present) may be an
indication of a partially clogged sample line. Compare FLOW in the GAUGES menu when sampling
and during calibration. Increases in FLOW during calibration of more than 0.1 LPM is an indication
of sample line clogging that restricts the free flow of excess calibration out through the sample line.
Clean or replace the sample line to restore proper calibration accuracy.
10.9.
Troubleshooting by status message
STATUS
Observations
Causes and/or Corrective Action
TEMP LOW
HEAT “on” continuously
Proper voltage levels not present at terminal.
Insufficient warm-up time. Wait up to 45 to 90
minutes after power is turned on.
Heater failure
Heater relay failure in controller
Loose controller connections on Terminals 31-37.
Insulation and/or enclosure covers not in place.
Overtemperature thermostat activated – requires
manual reset.
Overtemperature thermostat removed or not
installed, and jumper not in place.
TC2 thermocouple measuring circuit failure.
TC2 FAIL
HEAT is “off”
And
HSG TEMP in GAUGES menu
has negative temperature reading
TC2 thermocouple open circuit or loose connection
Tighten all connections
TEMP HI
HEAT LED is “OFF”
And
HSG TEMP on GAUGES menu
reading above SET TEMP by
more than +5C.
Mis-wiring of AC power to heater terminals instead
of AC input terminals.
Failure of controller circuit.
Failure of heater relay, or short circuit to AC heater.
TC2 thermocouple measuring circuit failure.
PrevEx®InstructionManual
77
TROUBLESHOOTING
STATUS
Observations
CHK FLOW
CHK FLOW message cycling
Service Needed Relay Activated
Fault LED cycling with message
or
Or
LOW FLOW
Fault LED indicator “on” and
FLOW measurement in GAUGES
menu less than LOW FLOW
setting (1.4 LPM typical)
DOWNSCLE
FLOW HIGH
FLAMEOUT
78
Causes and/or Corrective Action
Sample and/or Exhaust filters clogged. Change
filter(s).
Flame arrestors starting to clog. Remove, clean
and reinstall.
Low compressed air pressure. Verify/set to 20psi.
Sample line starting to clog. Disconnect sample line
at sensor. Clean line.
Exhaust line starting to clog. Disconnect exhaust
line at sensor. Clean line.
Pressure transducer tubes loose or slightly leaking
on back of electronics. Tighten and/or replace.
Pressure transducer tubes reversed. Verify correct
connections.
Failure of measuring circuitry or pressure sensor.
Call for service.
Aspirator nozzle plugging, clean.
Sample flow orifice loose, inspect and tighten.
READING < -10% LFL
Drift from low fuel supply pressure.
Drift from impurities in propane fuel supply.
External or internal fuel line leak, check and
tighten.
Improper zero calibration without zero gas. Zero on
slight upscale reading.
Contaminated zero gas, such as oil in compressed
air line.
Insufficient zero gas pressure.
Contaminated thermocouple needs cleaning.
Fault LED indicator “on” and
FLOW measurement in GAUGES
menu at or above the limit
Air pressure too high, causing excessive suction in
aspirator and too high a flow value:
SNR671 < 3.1 LPM
SNR672 < 2.9 LPM
SNR674 < 2.6 LPM
SNR675 < 2.4 LPM
Process pressure too high, causing excessive
sample flow.
Differential pressure between sample inlet and
exhaust too high, causing excessive sample flow.
Clogged sample orifice, causing excessive
pressure drop at normal flow rate.
Flow Transducer failure, causing high electronic
signal, call for service.
GAUGES/FLAME
GAUGES/HSG TEMP
Indication of a sensing flame
failure – without which the sensor
will not read sample.
Low fuel, fuel leak, or insufficient fuel inlet
pressure. Replace/set to specified value.
Ignition circuit not lighting the flame. Repeat
RESET.
No visible spark during ignition. Call for service.
Lack of oxygen in sample stream. Call for service.
Air pressure low or not connected.
Fuel regulator failure. Call for service.
Control Instruments Corp.
TROUBLESHOOTING
STATUS
Observations
Causes and/or Corrective Action
CHK RDNG
-10% < READING < -7%
Same as DOWNSCLE.
CHK ZERO
Or
ZEROFAIL
CHK SPAN
Or
SPANFAIL
CHK DATA
CHK ZERO message cycling
Service Needed Relay Activated
Fault LED cycling with message
or
Fault indicator “on”
CHK SPAN message cycling
Service Needed Relay Activated
Fault LED cycling with message
or
Message may appear at the end
Fault LED indicator “on”.
CHK DATA message cycling
Service Needed Relay Activated
Fault LED cycling with message
Zero calibration gas not connected.
Incorrect zero gas or incorrect pressure.
Zero gas oxygen concentration not 20.9%volume.
Must use clean, dry compressed air.
Insufficient fuel pressure at fuel inlet.
Drift from fuel regulator requires readjustment until
FLAME measurement is 500C under zero
conditions.
Span gas not connected to inlet.
Incorrect span gas type or concentration.
Insufficient span gas pressure.
Incorrect CAL RDNG setting.
CAL TIME too short to allow time to respond.
Incorrect alignment between thermocouple and
burner.
Thermocouple requires cleaning to remove
accumulated debris.
Sample line leaks in analyzer. Tighten fittings
and/or replace o-rings.
DATALOST
TYPE setting blank -------Other settings may be wrong
Fault LED and relay active.
RAM FAIL
or
EE FAIL
Memory failure
ROM FAIL
10.10.
Memory failure
Self-diagnostics has detected an unintentional
change in a setting. See section 9.3.5.
Check all register settings. Perform a calibration.
Self-diagnostics has detected an unintentional
change in a setting that cannot be recovered. See
section 10.10.
Loss of power or power disturbance during poweron self test or during calibration.
The setting TYPE must be correct and not blank.
Enter TYPE in ALARMS menu. Enter SERIAL if
necessary. Perform RESET.
Check all other settings. Perform a calibration.
Controller failure or power interruption or power
disturbance during power-on self test. Cycle
power “off” and then “on,” if fault repeats controller
may require factory repair to replace faulty RAM
memory or EEPROM.
Controller failure or extreme power line
disturbance. Perform reset command, wait five
minutes, if fault repeats controller may require
factory repair to replace faulty ROM memory.
and COLD START
Settings are stored in RAM memory and are also saved in EEPROM. When power is turned off, the
settings in RAM are lost but the settings in EEPROM are preserved. When power is turned on, the
settings are copied from EEPROM into RAM. When a setting is changed intentionally through a
menu or through the serial port, it is changed first in RAM and then is copied to EEPROM within
one minute. During operation, the settings in RAM are tested continuously to make sure that they
stay within acceptable limits, and that they match the settings stored in EEPROM. This helps prevent
an unintentional change in a setting in RAM from a momentary fault or power interruption.
DATA LOST
PrevEx®InstructionManual
79
TROUBLESHOOTING
The acceptable limits for some settings depend on the TYPE setting (example: HSG TEMP). So if the
self diagnostics detect that the TYPE setting itself is lost, a DATA LOST fault is given and the analyzer
cannot operate until the TYPE is set. The TYPE (and also the SERIAL) setting are written once at the
factory and ordinarily cannot be changed. But during a DATA LOST fault, these settings can be reentered. After TYPE is set, a RESET command or a off/on power cycle will lock out changes to the
TYPE and SERIAL registers.
The COLD START command allows the TYPE and SERIAL registers to be changed even if they have
not been lost. It should only be used during factory repair procedures. The RESET command (or a
power cycle) clears the COLD START condition, locking out further changes to the TYPE and SERIAL
registers.
To recover from DATA LOST :
1. Enter the correct TYPE in the ALARMS menu.
2. If necessary, correct the SERIAL number in the ALARMS menu.
3. Check the SET TEMP in the GAUGES menu.
4. Use the RESET command to clear the COLD START condition.
5. Use the ACKNWLDG command to clear the CHK DATA service-needed message and relay.
6. Verify all settings.
7. Perform a FULL CALibration.
10.11.
Drift
Most causes of drift are relatively minor, and do not cause error outside of the specified accuracy.
The specifications for pressure, flow, temperature and oxygen effects should be reviewed to
determine if the drift is due to one of these specified effects.
Some causes of drift are more significant, and can activate faults or service-needed messages.
10.11.1.
Initial drift
Drift is sometimes observed during the first 24 to 48 hours after initial startup. It may be due to air
trapped in the fuel line, or other causes. The analyzer then stabilizes and drift stops.
10.11.2.
Fuel regulation
Loss of fuel regulation can cause a significant amount of drift, even flameout. The fuel pressure must
be above the minimum at the fuel inlet. The fuel inlet fittings, which contains a sintered metal filter,
must be clean. This problem is diagnosed when an increase in the fuel supply pressure of +10% or
more causes more than +1% to +2% LFL increase in the reading.
10.11.3.
Fuel purity
Impure fuels cause drift. The contamination may be in the fuel itself. Propane fuels are more likely to
have purity problems than hydrogen, especially if the propane supply is subjected to temperature
changes. Or the contamination may be residue of sealant, flux, oil, etc., in the fuel line. This
contamination may be slowly released into the fuel, and can vary in magnitude over time from
changes in temperature and pressure. Clean fuel tubing and pure fuels are essential.
10.11.4.
Sample line contamination
An obstruction or clog in the sample tubing can cause drift.
Heated processes sometimes produce vapors from high boiling point substances that can condense in
the sampling system, especially if the sample tubing is unheated or insufficiently heated. This
80
Control Instruments Corp.
TROUBLESHOOTING
contamination, when subjected to temperature changes, can release back into the sample stream and
interfere with the readings. If this occurs, the sample tubing temperature must be increased.
During calibration, test gases exit through the sample tubing. A clog in the sample tubing can cause
pressure in the flame cell that shifts the reading by several %LFL during calibration. This condition
can be observed by comparing the FLOW in the GAUGES menu when sampling vs. when calibrating.
FLOW increased of more than 0.1 LPM during calibration is an indication of partial sample line
clogging than can result in sample reading shifts of several %LFL after a completed calibration.
10.11.5.
Thermocouple or burner contamination
An accumulation of material on the thermocouple or burner, in particular silicones, can slightly
insulate the thermocouple from the sensing flame and cause abnormally low zero readings. Such
contamination usually presents itself as zero and span drift, and lower-then-expected readings.
PrevEx®InstructionManual
81
SPARE PARTS
11.
Spare Parts
11.1.
Parts for Preventative Maintenance
For maintaining the flow system of SNR671, SNR672 and SNR674:
FLT012
4 per year
Filter element, flame cell sample and exhaust
ORG005
4 per year
O-Ring, 1 3/16‖ ID, Viton, Flame arrestor cap
For maintaining the flow system of SNR675:
FLT012
4 per year
Filter element, flame cell sample and exhaust
ORK005
2 per year or as needed O-Ring, 1 3/16‖ ID, Flame arrestor cap, Kalrez®
11.2.
Parts for Routine Maintenance
Replacement O-rings for re-assembly of the SNR671, SNR672 or SNR674 flame cell:
ORG044
1
O-Ring, Viton, 2.484‖ ID, Flame cell
ORG041
2
O-Ring, Viton, 0.359‖ ID, Flame cell to aspirator block
Replacement O-rings for re-assembly of the SNR675 flame cell:
ORK046
1
O-Ring, 2.484‖ ID, Flame cell, Kalrez®
ORK047
2
O-Ring, 0.359‖ ID, Flame cell to aspirator block, Kalrez®
11.3.
Parts for Maintenance and Repair
These parts are needed occasionally during maintenance and repair and should be kept on hand.
ORF024
Orifice, Sample flow measurement
FLT087
Sintered metal filter to protect orifice
NZL001
Nozzle, aspirator
SNP189
Flame arrestor
BRN006
Burner, with nuts
FUS037
Fuse, 5 amp, 5mm x 20mm, quick acting, IEC 127 code F
FUS038
Fuse, ½ amp, 5mm x 20mm, time lag, IEC 127 code T
11.4.
Parts for Repair
These parts may be needed to replace a failed component.
THC002R
Thermocouple, flame and block temperature
RSH001
Fuel Restrictor, Hydrogen, standard unit
RSH002
Fuel Restrictor, Hydrogen, air dilution type unit
RSP018
Fuel Restrictor, Propane
VLV079
Solenoid valve, zero or span, 120 VAC
VLV083
Solenoid valve, zero or span, 230 VAC
PRV058FR
Fuel Regulator
HTR077R
Heater, 385 watt, 120 VAC (was part number HTR057)
HTR078R
Heater, 385 watt, 230 VAC (was part number HTR058)
TOL003
Tool, flame thermocouple bending and alignment
TOL047
Tool, thermocouple alignment
TOL044
Quick-wedge locking screwdriver for orifice filter service
TOL046
1/8‖ Hex socket driver
HSG237R
Display/Controller assembly, include serial number when ordering.
CBL229
Ignition cable, replacement, SNR675 only
SPK031
Ignition cable, replacement, SNR671, SNR672 and SNR674
SPK021
Spark plug, flame ignition
SNP366
Calibration gas restrictor/filter
SNP374
Fuel inlet restrictor/filter
82
Control Instruments Corp.
SPARE PARTS
11.5.
Spare Part Photos
The coin in the photographs is approximately 2 centimeters, or 3/4 inch.
Burner assembly24: part # BRN006
Ignitor cable: part # CBL229 for SNR675
Filter element: part # FLT012
Controller: part# HSG237R
Fuses: part#s FUS037 and FUS038
Heater elements - part#s HTR077R (120VAC) and HTR078R (220 VAC)
Use HTR077R to replace HTR057 heater
24
Use HTR078R to replace HTR058 heater
Air dilution types (D, K) use a shorter burner, part# BRN050, having a 0.5 inch (1.3 cm) gap.
PrevEx®InstructionManual
83
SPARE PARTS
Aspirator nozzle: part# NZL001
Sample flow orifice: part# ORF024
Orifice inner diameter is 0.025 inches (#72 drill).
O-Ring, Flame Arrestor Cap, viton: part# ORG005 and Kalrez: part#ORK005
Viton O-Rings (ORG) are for lower temperatures. Kalrez (ORK) is required for high temperatures.
O-Ring, block seals, viton: part# ORG041 and Kalrez: part# ORK047
O-Ring, flame cell seal, viton: part# ORG044 and Kalrez: part# ORK046
84
Control Instruments Corp.
SPARE PARTS
Fuel Regulator: part# PRV058FR
Flame Arrestor: part# SNP189
Fuel Restrictor, hydrogen25: part# RSH001 (or RSH002) and propane: part# RSP018
Calibration Gas Inlet Restrictor: part# SNP366 Fuel Inlet Restrictor / Filter: part# SNP374
Spark Plug Assembly: part# SPK021
25
Thermocouple assembly: part# THC002
Air dilution type analyzers use hydrogen fuel restrictor part number RSH002.
PrevEx®InstructionManual
85
SPARE PARTS
Tool: part# TOL003
Tool: part# TOL047
Used to set the standard burner-thermocouple gap,26 and spark gap
Solenoid valve, calibration: part#s VLV079 (120 VAC) and VLV083 (230 VAC)
Air Regulator, Part# PRV069,
Ignitor cable: part # SPK031
for Air-dilution Types only
for SNR671, SNR672 & SNR674 only
26
Air dilution types (D, K) use a shorter burner, part# BRN050, having a 0.5 inch (1.3 cm) gap.
86
Control Instruments Corp.
SERIAL COMMUNICATIONS
12.
Serial Communications
Data can be transferred between one or more analyzers, and a single host device, using the Modbus
Remote Terminal Unit (RTU) protocol. The host device sends polls, to which the analyzer replies.
12.1.
Serial Communications Specifications
Specification
Supported commands
Description
Command 3
“Read Output (Holding) Registers”
Command 6
“Preset Single Register”
Command 16
“Preset Multiple Registers.”
Command 16 limit
Limited to one register in length (special case).
Command 3 limit
Limited to 127 registers in length.
Broadcast mode
Supported for commands 6 and 16.
Serial port hardware
Half-duplex RS485
Data format
8 bits, no parity, 1 stop bit
Baud rates
Baud rates from 300 to 19,200 are supported
Standard baud rate
9600
Maximum poll rate
Eight per second at 9600 Baud, sixteen per second at 19200 Baud
Receive-transmit delay
Minimum: 5 characters between receipt of poll and reply.
Maximum: 250 milliseconds, if maximum poll rate is reached
Error handling
Invalid start register address
Command ignored, no reply
Read more than 127 registers
Command ignored, no reply
CRC error, poll corrupted
Command ignored, no reply
Read over page boundary
Command ignored, no reply
Read invalid page
Command ignored, no reply
Data written outside valid limits
Reply is made but data is ignored
Read of unsupported register
00H Data returned in reply
12.2.
Serial Communications Notes
The modbus master should be secured from unauthorized or unintentional changes. Networked
access is not recommended.
WARNING! Serial communications must not be used for critical safety functions such as process
shutdown.
Writing illegal data outside the register‘s acceptable limits is acknowledged with a reply, but the data
is ignored. The modbus master should verify completion of write commands by a subsequent read of
the register.
Data written to the COMMANDS register is cleared as soon as the command is executed. Reading the
COMMANDS register most likely returns 00H data, even if the register has just been written. The host
should verify COMMANDS by reading the STATUS register.
Data written to non-volatile registers are saved to the EEPROM sixty seconds later. When several
write commands are received consecutively, that is, with less than 60 seconds between them, the
EEPROM is written 60 seconds after the last command. The SAVE ALL command saves to the
EEPROM immediately.
PrevEx®InstructionManual
87
SERIAL COMMUNICATIONS
Some modbus master devices prefer to receive a reply with the register data formatted with the low
order byte transmitted first. Read registers at pages 4 or 5 to get register data formatted ―lo:hi.‖
Page#
Hexadecimal addresses
Accessible contents
00
0000H through 00xxH
Registers 1 through 64
01
0100H through 01xxH
Registers 257 through 272
04
0400H through 04xxH
Copy of registers 257 through 272, lo:hi format,
effective register numbers 1025 through 1040
05
0500H through 05xxH
Copy of registers 1 through 64, lo:hi format,
effective register numbers 1281 through 1344
12.3.
Register Conversion Factors
After it is acquired, the serial port data is converted into engineering units using a conversion factor.
For the following registers, the data is a signed 16-bit word. Negative numbers are in two‘s
complement form. To convert the register data, multiply by the conversion factor in the table.
REGISTERS
READING
PEAK HI
PEAK LO
CAL RDNG
WARNING
DANGER
MA TEST
MA CAL
MA FAULT
MA TEST
MA CAL
MA FAULT
HSG TEMP
SET TEMP
FLAME
RAW ZERO
RAW SPAN
SPAN °C
FLOW
CHK FLOW
LOW FLOW
4 MA ADJ
20 MA ADJ
VARIOUS
Format
Conversion Factor
Reading
Standard unit with 100%LFL measurement range, multiply
by 0.00390625 %LFL
27
Reading format
expressed as milliamps
Multiply by 0.000625, then add + 4.0 Milliamps
Temperature
Multiply by 0.24426 C
Flow Rate
Multiply by 0.00172936 Liters per minute
Milliamps
0.1 Milliamps
ON/off
ON = 1, active; off = 0, inactive
27
Analyzers with air dilution options using software Version 5.08 and earlier have a 200%LFL range. For
these analyzers multiply by 0.0078125.
88
Control Instruments Corp.
SERIAL COMMUNICATIONS
12.4.
Registers
Register
Name
#
1
READING
M
E
N
U
The flammability reading in Percent Lower Flammable Limit (%LFL)
STATUS
2
PEAK HI
38
Register 50 is a copy of READING that includes the effect of MA CAL, MA FAULT and MA
TEST register functions.
Device status messages, codes, and their meanings
Message
Code
Meaning
Normal
0
Normal operation, no alarms
Warning
1
Warning alarm, reading above warning level
Danger
2
Danger alarm, reading above danger level
Downscale
3
Fault, reading lower than –10%LFL
Zero On
4
Zero calibration or zero test in progress
Span On
5
Span calibration or span test in progress
Purging
6
Purging calibration gases
Cal ends
7
Calibration ending
Zero fail
8
Zero calibration failed, result unacceptable
Span fail, low
9
Span calibration failed, result too low
Span fail, high
10
Span calibration failed, result too high
Warm-up
11
Power-on time delay for self diagnostics
RAM test
12
Self diagnostic of RAM
RAM fail
13
RAM has failed self diagnostic test
Data lost
14
Checksum for nonvolatile data in EEPROM failed
EE fail
15
Self diagnostic check of EEPROM failed
Temp low
18
Temperature of analyzer is too low
Temp high
19
Temperature of analyzer is too high
Flow Low
20
Sample flow rate too low.
Flow Hi
21
Sample flow rate too high.
A/D fail
24
Self check of A/D converter failed.
TC2 Fail
25
Thermocouple for temperature control failed.
Flameout
26
Sensing flame is out.
ROM fail
27
Continuous self-diagnostic of ROM has failed.
Highest reading taken since last reset command
PEAK LOW
39
Lowest reading taken since last reset command
HSG TEMP
9
Actual flame cell housing temperature in Degrees Centigrade
Assembly
Min
Flame cell housing temperature
SNR671
50C
set point in Degrees Centigrade
SNR672
100C
SNR674
100C
SNR675
100C
50
G
A
U
G
E
S
Register Contents
Registers that can be written are indicated by this symbol: .
SET TEMP
24
FLOW
15
LOW
FLOW
23
CHK
FLOW
42
FLAME
11
Max
Default
65C
60C
153C
120C
210C
280C
200C
250C
Sample flow rate in Standard Liters per Minute
Assembly
Min
Max
Default
Sample flow rate at which “Low
SNR671
1.4
3.0
1.4
Flow” fault is activated, in
SNR672
1.4
2.7
1.4
standard liters per minute.
SNR674
1.4
2.5
1.4
SNR675
1.4
2.3
1.4
Level at which the CHK FLOW “service needed” message and relay will activate.
Do not write to this register via modbus.
Flame temperature (Thermocouple TC1 reading) in Degrees Centigrade
PrevEx®InstructionManual
89
SERIAL COMMUNICATIONS
REGISTER
NAME
C
A
L
M
E
N
U
RAW ZERO
29
RAW SPAN
30
CAL TIME
CAL RDNG
M
E
N
U
90
28
7
43
SPAN C
56
SPEED
20
CAL LOCK
C
O
M
M
A
N
D
S
#
COMMANDS
60
8
REGISTER CONTENTS
Flame temperature from zero calibration in degrees Centigrade
Minimum value is 450C
Maximum value is 550C
Default value is 500C.
Flame temperature from span cal minus the raw zero, in degrees Centigrade.
Duration of each calibration interval in minutes
Minimum setting 1 minute, maximum 4 minutes. Default is 1 minute.
%LFL reading for span calibration.
Minimum value is 40%LFL except P type,which allows 25%LFL.
Maximum value is 80%LFL. Default value is 60%LFL.
Register 43 is a copy of CAL RDNG from the last successful calibration.
Setting for expected RAW SPAN temperature rise during span calibration
Type
Standard
P-type
D- and K-type
Minimum
105°C
68
50
Maximum
140°C
140
70
Default
125°C
80
60
Speed of response and noise filter
Off
0
Slowest setting. Available with K type only.
Low
1
Default setting for D type
Med
2
Default setting for all but D type
High
3
Fastest setting
Indication of calibration lock. Read only.
Hardware Lock
Bit 0
Software Lock
Bit 1
Execute a command to control the device
0
(no commands, inactive)
Reset
200H
Reset alarms
Acknowle
100H
Silence the horn, clear “service needed” relay
dge
Calibrate analyzer with gas, adjust settings, activate faults if response unacceptable
Zero Cal
300H
Perform zero calibration and adjust zero
Span Cal
400H
Perform span calibration and adjust span
Full Cal
500H
Perform zero and span calibration and adjust
Test analyzer response with gases, but do not adjust the settings, ignore faults
Zero Test
600H
Test zero with gas, do not adjust
Span Test 700H
Test span with gas, do not adjust
Full Test
800H
Test zero and span, do not adjust
Commands affecting EEPROM
Save All
900H
Save all settings to EEPROM
Cold Start
0A00
Force device into COLD START condition. Do not use.
Commands for remote control - not on menu
0B00H
Emulates “Menu” pushbutton
0C00H
Emulates “Select” pushbutton
0D00H
Emulates “Flashlight” activation
Commands for security - not on menu
0E00H
“Momentary lock” - internal use only. Do not use.
Lock
0F00H
Locks out calibration, software lock.
Unlock
1000H
Unlocks calibration.
Control Instruments Corp.
SERIAL COMMUNICATIONS
REGISTER
NAME
O
U
T
P
U
T
S
M
E
N
U
C
O
M
P
O
R
T
M
E
N
U
#
RLY TEST
45
MA TEST
44
4 MA ADJ
25
20 MA ADJ
31
MA CAL
MA FAULT
26
REGISTER CONTENTS
Relays activated for test. Format is identical to RELAYS register. Test is run
through menu access only - do not write to this register with modbus (serial
communication).
Circuit test of milliamp output, in milliamps, increases output only, deactivates
upon leaving menu. Test is run through menu access only - do not write to this
register with modbus (serial communication).
Circuit adjustment of milliamp output at the 0%LFL (4 milliamp) point – factory set
Range is +/- 2 milliamps. Default value is 0.
Circuit adjustment of milliamp output at the full scale (20 milliamp) point –
factory set.
Range is +/- 2 milliamps. Default value is 0.
Value for milliamp output during calibrations
Minimum is 2.5 milliamps, maximum 22.7 milliamps, default is 22.1 milliamps.
Value for milliamp output during faults
Minimum is 2.5 milliamps, maximum 22.7 milliamps, default is 21.0 milliamps.
32
CONTROL1
36
Assigns a COMMAND to the CONTROL1 input. (See COMMANDS register)
CONTROL2
37
Assigns a COMMAND to the CONTROL2 input. (See COMMANDS register)
RLY CNFG
58
SET BAUD
22
BAUD RATE
47
AUTOBAUD
48
ADDRESS
21
ID NBR
19
Configuration setting for the HORN relay
00 Default setting. The relay is used for the HORN function.
01 AIR/FUEL function. The relay energizes (contacts close) when flame cell
is at proper operating temperature.
02 OVERRIDE function. Relay is always energized (contacts always closed)
Default Baud Rate Setting
(See below for allowable settings and Baud rates)
Baud Rate Currently In Use. Can differ from the default setting if AUTOBAUD is
“on.” The allowable settings are:
0010H
19200
0011H
9600
Standard value is 9600 Baud
0012H
4800
0013H
2400
0014H
1200
0015H
600
0016H
300
Control for automatic baud rate detection feature (vs. fixed baud rate setting)
0
Off
Baud rate fixed, equals “SET BAUD” value
1
On
Device automatically seeks proper baud rate
Port address of device
Valid settings are 1 to 255, Default setting is 1.
Note: the address in the modbus data packet is one less than that stored in
the address register “address 1 = 0000H”
User-assigned identification number.
Valid settings are 0 to 99. Default setting is 0.
PrevEx®InstructionManual
91
SERIAL COMMUNICATIONS
REGISTER
NAME
WARNING
5
DANGER
6
RATE
61
LATCHES
A
L
A
R
M
S
#
17
FAILSAFE
18
AUTO IGN
35
VERSION
M
E
N
U
TYPE
62
REGISTER CONTENTS
The warning alarm level, in the same format as reading
Default setting is 40% LFL
Adjustable from 5% LFL to 60% LFL.
Should be set below the DANGER level.
The danger alarm level, in the same format as reading
Default setting is 50% LFL
Adjustable from 10% LFL to 60% LFL
Enables and disables the rate-of-rise alarm.
ON = Rate-of-rise alarm is enabled
OFF = Rate-of-rise alarm is disabled
Alarms that will latch until manually reset, versus those that will auto reset
Format is identical to RELAYS register.
Default is WARNING, DANGER AND FAULT set to latching.
Relays that are failsafe (normally energized) and which de-energize upon
activation of the alarm. WARNING, DANGER AND FAULT relays are always
failsafe. Format is identical to RELAYS register. Do not write to this register via
modbus - change only through the operator panel.
Automatic Re-ignition setting
0 = None, single attempt to ignite is made upon flameout, after reset.
1 to 120 = Number of re-ignition attempts at 15 second intervals.
Default setting is 0, disabled.
Software version (for complete Version header see below registers 257 - 272)
Analyzer type - This register is written once at factory
0
Undefined – this value will cause DATA LOST fault
1
SNR671
2
SNR671D
3
SNR672P
4
SNR672
5
SNR672D
6
SNR672K
7
SNR674P
8
SNR674PL
9
SNR674
10
SNR674D
11
SNR675
12
SNR675D
13
SNR675K
Options:
D = Air dilution option
P = Allows 0.6% volume Propane calibration gas
K = Air dilution with ability to set SPEED to OFF
L = Low flow adjustment option (now standard on all types)
92
SERIAL
63
LANGUAGE
64
Serial number – displayed as year of production and serial, eg, 02-101 for year
2002 serial 101. Data in this register is the serial only. The year of production
is stored in the ASCII text string registers 257 to 272.
This register is written once, at the factory upon shipment.
Display language
0 = English (default)
1 = German
Control Instruments Corp.
SERIAL COMMUNICATIONS
REGISTER
NAME
FULLSCLE
RELAYS
DUMMY
A/D REF
SERVICE
VERSION
DISPLAY
#
3
4
49
46
16
59
257
thru
272
40
51
thru
55
MA SCALE
57
LINEAR
41
28
Register Contents
Note: These registers are accessible through the serial port
In some prior software versions LINEAR and MA SCALE were on menus.
28
Full scale measurement range. 100 for standard units.
Logical state of the control relays. This data matches the corresponding LED indicators.
A bit of 1 = “active”, 0 = “inactive”
Data is in binary format. Packed flags: 0000 0000 TISZ HFDW
T
I
S
Z
H
F
D
W
Heater
Ignition
Span solenoid valve
Zero solenoid valve
Horn relay
Fault relay
Danger relay
Warning relay
Copy of RELAYS in low byte position and FAILSAFE register in high byte position.
A register that performs no function, but can be used to debug serial communications
The reference voltage of the A/D converter. Should be 506 ± 25.
SERVICE NEEDED indication. A bit of 1 = “active”, 0 = “inactive”
Data is in binary format. Packed flags: 0000 0000 A0RD LSZF
F
Z
S
L
D
R
A
CHK_FLOW
CHK_ZERO
CHK_SPAN
CHK_LED - controls flashing of fault LED when any CHK_ bit is set
CHK_DATA
CHK_RDNG
AIR_FUEL
Device identification, in ASCII text string.
„ PREVEX „
Analyzer Model
„ VER 5.11‟
Software version
„ SNR67x „
Analyzer assembly number
‟ 2005 „
Analyzer serial number – year of production
Internal pointer used for display of version - do not use.
Copy of the LCD display buffer in ASCII.
The %LFL reading equal to 20 milliamps. Always 100%LFL. Older air dilution types D
or K at version 5.08 or lower adjusted to 100%LFL or 200% LFL.
For sensor with Air Dilution Option, type D or K, sets the linear range.
OFF
40% LFL
Standard setting without Air Dilution.
ON
80% LFL
Air Dilution installed and active.
For analyzers with air dilution option - D or K in the TYPE (eg SNR675K, SNR674D. etc.) at software
5.08 and earlier, the full scale is 200.
VERSION
PrevEx®InstructionManual
93
Drawing Index:
H7FTA124
C7FTA114
D7FTA119
C5SNR671
C7CAL129
B7FLT070
B7FLT067
B7CAL130
C7SRV135
C7HTR070
H7FTA182
Fax Troubleshooting Worksheet
FTA Mounting
Assembly Diagram
Wiring Diagram
FM Calibration Guide
Compressed Air Line Filter
End Of Line Filter
Calibration Kit
“Y” Purge Installation
Heat Trace Mounting
Maintenance Instructions
FAX this form to 973-575-0013
(Questions? Call 973-575-9114)
Troubleshooting Worksheet for PrevEx Flammability Analyzers (SNR671, 672, 674, 675)
Please answer all questions. Use additional paper if needed.
Company Name
Person to Contact
Email
Contact Phone
Conta
Equipment Serial Number(s)
ct Fax
Sales
Order Number
Serial numbers are indicated on the instruments serial plate, which is located on the side exterior of the instrument.
Describe the problem you are experiencing. What do you think is the cause of this problem?
Scroll through the instrument’s display menus. Record the values shown below
Gauges
Cal Menu
Alarms
Outputs
Reading
Raw Zero
Warning
RLY Test
COM Port
Set Baud
Status
Raw Span
Danger
mA Test
BaudRate
Peak Hi
Cal Time
Rate
mA Scale
AutoBaud
Peak Low
Cal Rdng
Latches
4mA Adj
Address
HSG Temp
Span °C
Fail Safe
20mA Adj
ID NBR
SET Temp
Linear
Auto Ign
mA Cal
Flow
Speed
Version
mA Fault
Low Flow
CAL Lock
Type
Control 1
Chk Flow
Serial
Control 2
Flame
Language
RLY Cnfg
Record any LEDs that may be lit on the front panel. Identify any indicators that are lit by filling in the circles.
Use the following legend: Off = | On = z Flashing = [
Fault
Danger
Warning
Horn
Zero
Span
Ignite
Heat
|
|
|
|
|
|
|
|
Alarm |
| Scan
Record the following values at the sensor:
a Fuel Inlet Pressure
PSIG
b
Dilution Air Inlet Pressure
PSIG
c
Span Inlet Pressure
PSIG
d
Zero Inlet Pressure
PSIG
e
Compressed Air Inlet Pressure
PSIG
Is the process under pressure or
vacuum at the sample point? Fill in
the value and the unit of measure
H7FTA124 rev. G
Where is the sample
pickup tube located?
Where does the
exhaust tube go to?
ab
c d
e
Customer / Field Drawings
The drawings which follow represent field connections and wiring.
Maintenance Instructions
!
Before disassembly make sure you have replacements for ALL O-Rings!
Always replace O-Rings after removal, or if they are brittle or damaged.
Low Flow
Disassembly Preventative
Reassembly
Sequence Maintenance * Troubleshooting * Sequence
Step 1
X
Step 1
Step 9
Step 2
Step 1
Step 2
Step 8
Step 3
Step 2
Step 3
Step 7
!
Check for leaks and recalibrate after any maintenance
procedure to verify proper operation.
G
Part Name, Quantity, and Number
Sample/Exhaust Tube and Leak Check
A
Flame Arrestor Cap (2) : SNP188
B
Flame Arrestor O-Ring (2) : ORG005 or ORK005 **
Step 4
Step 3
Step 4
Step 6
C
Flame Arrestor (2) : SNP189 Hand tight
Step 5
Step 4
Step 5
Step 5
D
Filter Element (2) : FLT012
Step 6
Step 4
E
Orifice Filter : FLT087 Use 10” Quick Wedge screwdriver (TOL044) to remove
F
Sample Flow Orifice : ORF024 Use 1/8” Allen Key (TOL046) to remove
Step 6
X
Step 7
X
X
Step 8
X
Step 7
P
-1/8th of a turn
Spring : SPR013
J
Spacer : SPC009
K
Nozzle : NZL001
Step 2
S
A
L
** ORK are Kalrez, used for Model SNR675.
ORG are Viton, used for all other models.
B
Leak Check
Flame Cell
L
Bolts (4) : MSC023 Use 5mm Allen Key to remove
M
Flame Cell Block : SNP219
N
Burner Plate : SNP215
P
O-Ring : ORG044 or ORK046 **
Check the analyzer for leaks. Plugging the
sample inlet tube should reduce the
sample flow to near 0 LPM, as indicated
in the GAUGES menu.
Thermocouple Detail
The thermocouple is
aligned directly above
the burner, 1/4” away.
!
Thermocouple
TC
Spark Electrode
1"
4
973-575-9114
SPARK
BURNER
Q
Bolts (4) : MSC007
R
Aspirator Block : SNP359
Use 5mm Allen Key to remove
1"
10
Thermocouple Gap Tool
Burner
S
Step 1
R
C
!
Step 3
M
F
D
Aspirator
Step 8
E
Plug : PLG002 Use 1/4” Allen Key to remove
H
K
Q
Aspirator Nozzle
G
* For each step in these procedures, remove, inspect, and
clean part, if necessary replace
it.
N
H
J
Flame Cell Detail
O-Ring (2) : ORG041 or ORK047 **
Thermocouple Alignment Detail: Use Gap tool TOL047
!
The electrode is located
1/10” behind and
above the back edge of
the burner.
©2004 Control Instruments Corporation (973) 575-9114. All rights reserved. H7FTA182 Rev B 9/09.
Maintenance Instructions
Monthly Maintenance
How to Display and Change a Setting
Press Menu to move
between menus
Press
Select
Press Select to Press Menu again to
enter menu
display registers
on EXIT register to leave menus
Press Select
Press Select yet again,
again to display to change a setting
register’s value
! Wait until flashing stops
to keep the new setting
Menu
to escape
and keep the old setting
! Press
Press Menu to go
to next register
! After 3 minutes of inactivity the display automatically exits the menu
Menu Explanations
Registers
COMMANDS
RESET
ACKNWLDG
ZERO CAL
SPAN CAL
FULL CAL
ZERO/SPAN/FULL TEST
LOCK CAL
Clear latched alarms and peak readings, retry ignition
Clear service needed messages
Start calibration of zero using air = 0% LFL
Start span calibration using test gas, typically 1.15% Ethylene = 60%
Automatically zero and then span using test gases
Similar to calibration, except no adjustment is made
Lock out calibration
READING
STATUS
PEAK HI
PEAK LOW
HSG TEMP
SET TEMP
FLOW
LOW FLOW
CHK FLOW
FLAME
Flammability reading in % LFL (Lower Flammable Limit)
Device status, alarms and faults
Highest reading since last RESET command
Lowest reading since last RESET command
Operating temperature of the flame cell housing in °C
Temperature setting for the flame cell housing in °C
Sample flow rate in standard liters per minute (LPM)
LOW FLOW fault occurs if flow goes below this LPM setting
CHK FLOW service needed occurs if flow goes below this LPM setting
The temperature of the flame in°C
RAW ZERO
RAW SPAN
CAL TIME
CAL RDNG
SPAN °C
SPEED
CAL LOCK
The temperature of the flame in air (at 0% LFL) - from zero calibration
Flame temperature increase expected from span calibration
Duration of the calibration in minutes
Flammability of the span gas, for example, 1.15% Ethylene = 60% LFL
Flame temperature increase expected from span gas, for example: 125°C
Speed-of-response setting
Present state of the calibration lock (ON/OFF)
WARNING
DANGER
RATE
LATCHES
FAIL SAFE
AUTO IGN
VERSION
TYPE
SERIAL
Warning alarm setting, % LFL
Danger alarm setting, 50% LFL or less
Rate-of-rise alarm setting (ON/OFF)
Alarm latches - hold until RESET
Relays in failsafe mode - normally energized
Automatic reignition of sensing flame, number of retries
Software version
Analyzer type
Serial number of the analyzer
GAUGES
Display the reading and status,
flow and temperatures, and other
operating parameters
CAL MENU
Calibrate the analyzer reading
Display the calibration settings
ALARMS
Configure alarms
OUTPUTS
Test relays and the 4-20 milliamp
output
Configure relays and controls
RLY TEST
Used to activate relays for testing alarms
MA TEST
Used to test 4 to 20 milliamp output
4 MA ADJ, 20 MA ADJ
Factory adjustment for milliamp output
MA CAL
Overrides milliamp output during calibration
MA FAULT
Overrides milliamp output during faults
CONTROL 1, CONTROL 2 COMMAND that executes from CONTROL input
RLY CNFG
Horn relay can be configured as AIR/FUEL cutoff
COM PORT
! Calibrate safely - never calibrate if combustible gases or vapors
might be present.
Turn calibration cylinders on and set pressure at analyzer inlet to
20 PSIG. Do not over or under pressurize.
Use FULL CAL on COMMANDS menu to initiate the automatic
calibration sequence.
Menus
Reset latched alarms
Acknowledge service needed
messages
Initiate and control calibrations
Calibration
For each analyzer, observe the reading during the calibration
process:
1 Zero LED is on.
2 Reading is near 0% LFL.
3 After about one minute (CAL TIME on CAL MENU)
reading adjusts to 0% LFL.
4 Zero LED is off. Span LED comes on.
5 Reading climbs up to near CAL RDNG, typically about
60% LFL.
6 After about one minute reading adjusts to CAL RDNG.
7 Span LED off. Zero LED back on for about 30 seconds
to purge. Reading falls back to 0% LFL.
Gauges
Regularly check the settings and reading on the GAUGES menu.
Alarms
Use RLY TEST in OUTPUTS menu to activate relays. Verify that the
FAULT and DANGER relays activate the E-Stop (shut-down, or
machine stop).
Notes
20 PSIG compressed air allows the analyzer to use fuel safely.
Keep the fuel and power off until the air is on and checked.
Compressed air drives the sample flow. Keep air pressure steady
and at 20 PSIG or else LOW FLOW may occur.
The sensing flame is fed by a small flow of fuel. The fuel pressure at
the inlet must be high enough to make a stable sensing flame or
else the reading may drift.
The analyzer uses AC power for its heater and electronics. When
first turned on, the STATUS will be TEMP LOW and the heater LED
will be on until the analyzer temperature (HSG TEMP) reaches its
operating temperature setting (SET TEMP). When analyzer reaches
operating temperature, the heater LED cycles on/off. Analyzer may
still be in fault condition FLAMEOUT.
When in FLAMEOUT (FLAME temperature less than 450˚C), use
RESET command to re-ignite sensing flame.
For serial communications settings only (See Manual)
©2004 Control Instruments Corporation (973) 575-9114. All rights reserved. H7FTA182 Rev B 9/09.