Teledyne Analytical Instruments Model 311 Portable Oxygen Analyzer Manual
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The sensor(s) used in this instrument uses electrolytes which contain substances that are
extremely harmful if touched, swallowed, or inhaled. Avoid contact with ANY fluid or powder
in or around the unit. What may appear to be plain water could contain one of these toxic
Flush contact area with cold water for several minutes.
Seek medical attention.
Flush with cold water for at least 15 minutes. Seek
immediate medical attention.
Drink milk or milk of magnesia. Seek immediate medical
Move immediately to an area of fresh air, or assist victim
to fresh air. If victim is having difficulty breathing, use
artificial respiration or administer oxygen. Seek immediate
TABLE OF CONTENTS
Method of Analysis
1.3.1 Micro-Fuel Cell
1.3.2 Reliable Calibration
1.3.3 Integral Power Supply
1.3.4 Accuracy and Response
1.3.5 Compact Packaging
SUPPORTING EQUIPMENT AND SERVICES
3.2.1 Air Calibration Procedure
3.2.2 Standard (Span) Calibration Procedure
Positive Pressure Sampling
Atmospheric Pressure Sampling
Battery Power Supply Services
TRANSDUCTION AND TEMPERATURE COMPENSATION
SPARE PARTS LIST
APPENDIX - Effect of CO2 on B-2C Cell Life
TRACE OXYGEN ANALYZER
Description: The Teledyne Analytical Instruments (TAI) Model 311 is a
portable, intrinsically safe trace oxygen analyzer which can be operated without an external
power source and reliably calibrated without the use of cumbersome, questionable, so-called
“certified” calibration gases.
The instrument provides for trace oxygen analysis in decade steps ranging from 0-10 to 0-10,000
ppm (full scale) plus a special calibration range that encompasses the known oxygen
concentration of atmospheric air (209,000 ppm).
Sample oxygen is read from an extremely accurate integral meter (0.5% linearity) whose range of
measurement is determined by the position of the range selector switch. The 100 division meter
scale and the multiplying factor indicated by the position of the range switch determine the full
scale oxygen sensitivity of the instrument. The linear 5 inch scale (mirror equipped to eliminate
parallax) provides excellent resolution and accuracy.
Sample gas is introduced and vented via a pair of quick disconnect fittings that feature integral
shutoff valves which automatically close when the mating male fitting is withdrawn. The fittings
are an integral part of the measuring cell manifold so that internal sample passage volume is at an
absolute minimum. Sample flow control, although not critical (0.1 to 10 liters/min.) must be
accomplished with accessory equipment.
Method of Analysis.
The sample oxygen is measured by a unique
electrochemical transducer which functions as a fuel cell; in this instance, the fuel is oxygen.
Oxygen diffusing into the cell reacts chemically to produce an electrical current that is
proportional to the oxygen concentration in the gas phase immediately adjacent to the
transducer’s sensing surface. The linear, but minute, signal produced by the transducer from
trace oxygen is amplified by a two stage amplifier. The dual stages of amplification provide
enough gain to drive the 0-100 microampere meter and thermistor controlled network utilized to
compensate for the positive temperature co-efficient of the transducer.
the Model 311:
The following unique features are incorporated into
1.3.1 Micro-Fuel Cell: The Micro-Fuel Cell* is a sealed electrochemical transducer with no electrolyte to change or electrodes to clean. When the cell reaches the end of its
useful life, it is merely thrown away and replaced, as one would replace a worn out battery in a
flashlight. The life of the cell is warranted by TAI (see Section 4.4) in a fashion similar to that
employed by the manufacturers of automobile batteries. This procedure guarantees the customer
compensation for failure of a given cell to perform as specified.
1.3.2 Reliable Calibration. The unique qualities of the Micro-Fuel Cell allows
the user to calibrate the instrument with the most economical, reliable, abundant, standardization
gas there is -- atmospheric air.
The special “CAL” range of the instrument features a mark that coincides with the 209,000 ppm
oxygen concentration of air. By drawing air through the instrument (see the Sample Calibration
Procedure in Section 3.2) reliable calibration can be achieved.
After the electronics have been properly zeroed (a one-time factory operation), the instrument
cannot produce an output indication in the absence of oxygen; therefore, the need for a “zero”
standardization gas is obviated (Refer to Section 5 if readjustment is required).
1.3.3 Integral Power Supply. The differential power requirement (plus a
minus 3.6 volts D.C.) of the instrument amplifier is furnished by two internally mounted 750
milliampere hour nickel cadmium batteries. Fully charged, these batteries will provide enough
power to operate the instrument continuously for a period of about thirty-five (35) days.
Furthermore, an overnight charge on a one-month duty cycle should keep the original batteries
supplied usable for many years.
An integral charging circuit and a detectable power cord are provided so that the batteries may be
recharged from any 50 or 60 cycle, 105 to 125 volt, convenience outlet.
The instrument is designed to either sample or have its batteries recharged. Both operations
cannot be carried out simultaneously. TAI has deliberately interlocked the circuitry so that both
operations cannot be carried on at the same time.
Only when the selector switch is placed in the OFF position will the neon lamp on the back plate
of the Model 311 light up to indicate power to the battery charging circuit.
* U.S. Pat. Nos. 3,767,552 and 3,668,101
A current limiting resistor (R1 and R2) is potted into the end of each battery. This assures that
under no circumstances can more than 25 milliamperes (100 milliwatts) be switched or drawn
from either battery supply. This means that the Model 311-C may be used in explosive
atmospheres where arcs of 100 milliwatts or less can be tolerated. The Model 311 meets Factory
Mutual approval requirements as intrinsically safe for Class I, Division I, Groups A, B, C and D
This safety feature does not apply when the instrument is being charged (AC power cord
connected and selector switch in the “OFF” position). The instrument should not be used in
explosive atmospheres when the batteries are being charged.
To determine the state of the rechargeable batteries turn the range selector knob
counterclockwise to the battery test position and hold there (spring loaded switch). Observe that
the meter indicator stays within the battery limits, *if not, recharge of the batteries is in order).
Release Range Selector Switch, it will automatically return to the OFF position.
1.3.4 Accuracy and Response. The Model 311 provides monitoring accuracy
of ±2% of full scale or ±1 ppm, whichever is greater, at constant temperature. A ±5% of reading
accuracy is achievable throughout the operating temperature range of 30 to 125 Deg. F.
With a sample flowrate of 150 cc/min. 90% response is achieved in 10 seconds in the X10,
X100, X1000, and CAL range switch positions. When in the X1 (0-10 ppm) range, 90%
response is realized in 61 seconds.
1.3.5 Compact Packaging. The instrument is housed in a 6-1/8” X 9-1/2” X 55/8” aluminum case that is equipped with a carrying handle and foot pads. When in use, the
analyzer should be placed in an upright position on a level surface (off level positioning will
detract from meter accuracy).
Access to the instrument interior is gained by loosening (ccw) the three (3) 1/4 turn screw driver
type fasteners on the back of the outer case. The case may then be detached from the driver type
fasteners on the back of the outer case. The case may then be detached from the control of the
outer case. The case may then be detached from the control panel assembly. Further
disassembly may be accomplished by removing the back plate assembly from its four (4)
mounting standoffs and laying the two separated assemblies out as illustrated on the “Analyzer
Wiring Diagram”. The diagram is included among the drawings at the rear of the manual.
SUPPORTING EQUIPMENT AND SERVICES
Sampling Equipment. The customer must provide a means of controlling the
pressure and flowrate of the sample gas. For positive pressure applications, TAI suggests a
simple throttle valve installed in the sample line between the sample point and the analyzer. The
flowrate should be limited to between 0.1 and 10 liters/min.
IMPORTANT: If a pressure regulator is necessary or desirable, it must have a metallic
diaphragm. Regulators with organic or plastic diaphragms are permeable to oxygen and, if used
in the sampling system, will lead to high oxygen readings.
For atmospheric pressure sampling, connect a pump and flow control valve downstream from the
analyzer and draw (rather than push) the sample through the instrument.
TAI supplies three (3) male disconnect fittings with the instrument. One for installation of the
customer’s sample line; one to be used to open the vent fitting of the instrument, and one
(equipped with a plastic tube) for drawing air through the unit for calibration purposes.
Power Service. A source of single phase, 105 to 125 volt, 50 or 60 Hertz power,
capable of delivering a maximum of 1/4 ampere of current will be periodically required to
recharge the instrument’s battery power supply. An eight (8) foot, UL approved, 3-wire detachable power cord is provided with the instrument and should be stored in a safe place when not in
use. As a no cost option the 311 can be furnished with 220 volt, 50 or 60 Hertz charging power.
Introduction. The Model 311 is supplied completely assembled and ready for
instant use. The Micro-Fuel Cell is in place within the manifold, and prior to shipment the manifold was purged with an inert gas to eliminate all but traces of oxygen from the internal sampling
system. The integral shut-off valves in the quick disconnect sample fittings, if not disturbed, will
maintain this inert atmosphere within the manifold indefinitely. This can be demonstrated by
advancing the range selector switch to the X100 (0-1,000 ppm) position.
When the range selector is advanced from the “OFF” position, power to the instrument’s
circuitry is established. The meter will constantly respond to the residual oxygen within the
integral sample passages.
It is impossible to achieve a “perfect” seal of the internal sample system, and what the meter is
indicating is the diffusion -- consumption balance point of internal sample system and the MicroFuel Cell.
This “balance” point, with a properly calibrated instrument is always within the limits of the
X100 range. If the reading climbs off the limits of this scale, a leak in the manifold assembly is
TO EXTEND CELL LIFE AND MINIMIZE THE TIME REQUIRED TO MAKE THE
NEXT ANALYSIS, THE INSTRUMENT SHOULD ALWAYS BE PURGED WITH THE
SAMPLE OR AN INERT GAS PRIOR TO BEING TAKEN OUT OF SERVICE FOR
STANDBY OR STORAGE.
Calibration. The inherently constant output of the cell during its useful life
precludes a definitive calibration cycle. TAI feels that the interval between calibrations should
be dictated by the customer’s application. If the instrument is being used to certify the oxygen
content of a product for delivery, then, a calibration prior to certification would certainly be in
order. If, on the other hand, the instrument is being used to monitor or guard a sample and the
evidence provided by the analyzer will in themselves determine when a calibration check is in
order. The sensitivity of the analyzer should be checked at two to four week intervals.
DO NOT CALIBRATE THE INSTRUMENT UNLESS THERE IS A TRACE OXYGEN
GAS READILY AVAILABLE FOR PURGING IMMEDIATELY FOLLOWING THE
3.2.1 Air Calibration Procedure. Employ the following step by step
procedure to calibrate the instrument.
Stand the instrument upright on a level surface, and with the range switch in the
“OFF” position, check the alignment of the meter pointer with the zero mark on
the scale. Use the mirror to eliminate parallax, and adjust the screw on the face
of the meter, if necessary, until the pointer and zero mark are in precise coincidence.
Advance the range switch to the “CAL” position.
Install the plastic tube equipped male disconnect fitting in either of the analyzer’s
sample ports, and a blank disconnect fitting in the other port (direction of sample
flow is of no importance). A pump is recommended on the plastic tube. Pump
the tube until the meter reading is stable.
CAUTION: DO NOT SUCK ON THE TUBE WITH YOUR MOUTH, THERE IS A
POSSIBILITY THE MICRO-FUEL CELL MAY LEAK. THE CELL CONTAINS KOH
SOLUTION WHICH IS CAUSTIC AND EXTREMELY HAZARDOUS!
Unlock and adjust the span control until the meter pointer is in coincidence with
the “CAL” mark on the meter scale. BE SURE TO RELOCK THE
CONTROL AFTER THE ADJUSTMENT IS MADE.
Immediately after Step 4 has been accomplished, disconnect the tubing equipped
calibration fitting, and plug in either the sample or a source of inert gas.
If the instrument is to be used for sampling after the calibration procedure has been completed,
follow the decreasing oxygen reading by positioning the range switch so that the meter gives the
best possible resolution of the oxygen. DO NOT ATTEMPT TO ACTUALLY TAKE A
READING UNTIL THE METER INDICATION STABILIZES. If the sample oxygen
content lies within the limits of the X1 range (0-10 ppm), an overnight purge is recommended for
the instrument to recover sufficiently from the effects of the 209,000 ppm oxygen concentration
of air (over four decades of range differential). Recovery time is proportionally less the coarser
If, on the other hand, the instrument is not to be used immediately after calibration, and a low
ppm oxygen gas is being employed as a purge, allow the manifold to be purged overnight, and
then disconnect both male fittings. ALWAYS DISCONNECT THE SOURCE FITTING
FIRST, AND IMMEDIATELY THEREAFTER, THE VENT FITTING.
Standard (Span) Gas Calibration (optional)
- Zero gas
- (70-90%) of full scale of the primary (working) range
If the primary (working) range is a lower range, when
you change to a higher range recalibration is a must for
accuracy (see Figure 2 Chart, included).
Stand the instrument upright on a level surface, and with the range switch in the
“OFF” position, check the alignment of the meter pointer with the zero mark on
the scale, use the mirror to eliminate parallax and adjust screw on the face of the
meter, if necessary, until the pointer and zero mark is in precise coincidence.
Install a sensor.
Install quick disconnect, FIRST TO THE VENT then the sample inlet.
Purge the analyzer with a zero gas for 12-16 hours at 2 SCFH.
Advance the range to CAL.
Connect span gas.
Advance the range when oxygen level is decreasing, wait until the reading
Unlock and adjust span control until the meter reads the oxygen content.
Advance the range to CAL.
Disconnect the span gas.
Connect the sample gas.
Advance the range when the oxygen level is decreasing, so that the meter gives
the best possible resolution of the oxygen. DO NOT attempt to take a reading until the meter
Positive Pressure Sampling. When connecting the instrument to a positive
pressure sample source, ALWAYS proceed as follows:
Before making any connections to the instrument, establish a flowrate in the
sample line of from 0.1 to 10 liters/min. Allow the sample to vent to accomplish
long enough to purge the line free of air.
Install the vent fitting first, and then the sample source fitting. Be prepared to
make the connections in rapid order, so that atmospheric diffusion time through
the vent fitting is held to a minimum.
When disconnecting the instrument, reverse the procedure: source fitting first, and then vent
The objective of the connection -- disconnection procedure is to obviate the possibility of
pressurizing the manifold. IF A FLOWING SAMPLE WAS CONNECTED TO THE
MANIFOLD WITHOUT THE VENT FITTING IN PLACE, THE PRESSURE IN THE
MANIFOLD WOULD RISE AND BE EQUAL TO THE SAMPLE PRESSURE ALMOST
IMMEDIATELY. In such a situation, depending on the magnitude of the sample pressure,
leaks in the manifold might result.
Atmospheric Pressure Sampling. If the sample is at atmospheric pressure (or
slightly negative), a sample pump will be required downstream from the analyzer. The inlet side
of the pump should also be equipped with a throttle valve -- so that sample flow can be reduced
to between 0.1 and 10 liters/min. If pump loading is a consideration, the inlet side of the pump
will have to include a bypass path that is open to the atmosphere through still another throttle
valve. The sample path and bypass path may then be balanced by manipulating the two valves,
so that sample flow is within the prescribed limits without loading the pump.
UNDER NO CIRCUMSTANCES SHOULD THERE BE ANY RESTRICTIONS IN THE
LINE BETWEEN THE SAMPLE POINT AND THE ANALYZER -- as a partial vacuum
would then be drawn on the cell. Since the cell is a partial pressure sensitive device, any oxygen
readings taken under these conditions would be erroneous and vacuums in excess of one-third of
an atmosphere may damage the cell.
Battery Power Supply Service. The Model 311 is designed to be intrinsically
safe, and therefore is for use ONLY when it is not connected to the AC power line. TAI suggests
that an overnight recharge be accomplished every four (4) weeks of continuous use. To recharge
the batteries, place the range switch in the “OFF” position and connect the power cord to a
convenient outlet. NOTE: The amber charge lamp (back of case) will be lit during charging.
The integral charging circuit will automatically energize and regulate the battery charging
current when the switch is in the “OFF” position and the AC cord is plugged into the power
WARNING: DO NOT TURN THE RANGE SWITCH EITHER TO “BATT TEST” OR
TO ANY OF THE OPERATING RANGE POSITIONS WHILE THE UNIT IS PLUGGED
INTO THE POWER LINE! DOING SO MAY CAUSE THE INTEGRATED CIRCUITS
When recharging is completed, unplug the unit from the AC outlet. Turn the range switch to the
“BATT TEST” position or to the operating position.
NOTE: The “BATT TEST” position will not give a reliable indication of the battery
charge immediately after a charge cycle. Allow the unit to run for awhile before testing the
If the instrument is stored with the range switch in the “OFF” position (charge cord
disconnected), the period of time between charge periods is extended from one month to four
months. However, do not leave it longer than this time period.
Routine Maintenance. Beyond adhering to a battery recharge schedule, no
routine maintenance is required, as there are no moving parts in the instrument other than the
meter movement. The Micro-Fuel Cell is a sealed, modular component that should be replaced
only when faulty.
Cell Replacement. The characteristics of the Micro-Fuel Cell are similar to those
of a mercury battery in that both provide an almost constant output through their useful life, and
then fall off sharply towards zero at the end. If the sample being analyzed has a low (X1 range)
oxygen concentration, cell failure will probably be indicated by the inability to properly calibrate
the analyzer. The user will find that very little adjustment of the 10-turn span potentiometer will
be required to keep the analyzer calibrated properly during the duration of a given cell’s useful
life. If large, many turn adjustments (cw) are required to calibrate the instrument, or calibration
cannot be achieved within the range of the control, the cell should be immediately replaced (read
Section 5.4 before replacing cell).
To offset the possibility of not having a replacement cell available when it is needed, TAI
recommends that a spare cell be purchased shortly after the instrument is placed in service, and
each time the cell is replaced thereafter.
The spare cell should be carefully stored in an area that is not subject to large variations in
ambient temperature (75 Deg. F nominal), and in such a way as to obviate any possibility of
incurring damage. Under no circumstances, disturb the integrity of the cell package until the cell
is to be actually used. If the cell package is punctured and air permitted to enter, the cell will
immediately start to react to the presence of oxygen.
No tools are required to replace the cell in the instrument. Simply unscrew (ccw) the plug at the
bottom of the analyzer and the cell will drop out of the manifold cavity.
Remove the new cell from its package, and carefully remove the shorting clip. Do not touch the
silver colored sensing surface of the cell -- as it is covered with a delicate Teflon membrane that
can be ruptured in handling.
Place the cell on the end of the manifold plug -- so that the sensing surface of the cell is in
contact with the plug and the electrical contact plate end of the cell is facing upwards. Insert the
cell and plug in the manifold cavity, and screw the plug back into place. Apply as much pressure
as you can with your fingers, but use no tools.
After the cell has been installed, purge the instrument with an inert gas (or the sample), and then
proceed as directed in Section 3.2.1.
Cell Warranty. The Class B-2C cell employed in the Model 311 is warranted for
80,000 percent-hours or six (6) months of service (whichever occurs first).
With regard to spare cells, service time starts when the cell is removed from its shipping
package. The customer should stock only one spare cell per instrument at a time. Do not attempt
to stock- pile spare cells.
The Model 311 should not be used in applications where CO2 is a major component in the
sample. Concentrations of 1,000 ppm or less will not effect the cell performance. The following
page is a graph showing the effects of CO2 on cell life.
If a cell was working satisfactorily, but ceases to function before the warranty period expires, the
customer will receive credit, toward the purchase of a new cell.
Customer’s having warranty claims must return the cell in question to the factory for evaluation,
after obtained an RMA number. If it is determined that failure is due to faulty workmanship or
material, the cell will be replaced at no cost to the customer.
WARNING: Evidence of damage due to tampering or mishandling will render the cell
warranty null and void.
TRANSDUCER AND TEMPERATURE COMPENSATION
The Micro-Fuel Cell has an inherent positive temperature coefficient, the effects of which have
been minimized through the implementation of a calibrated thermistor compensation circuit.
Internal electronic calibration is accomplished by TAI. However, should there by any doubt
concerning it, the following procedure can be used to recalibrate. Refer to Schematic.
Move range switch to “CAL” position.
Adjust R1 (designated as R1 on Schematic B14463 and designated on the A1 PCB
module assembly as R28) such that the output of A1, pin 6, measures between 0
and +0.5 mV, ideally +0.3 mV.
Adjust R2 (designated as R2 on Schematic B14463 and designated on the A3 PCB
module assembly as R28) for 0 ± 1 mV at output of A3, pin 6.
Verify that the offset is the same on all ranges.
If a leak is suspected in the unit, DO NOT ATTEMPT TO TIGHTEN THE
THE FITTINGS ARE POTTED IN EPOXY AND
TIGHTENING THEM WILL BREAK THE SEAL!.
To check the leaks, TAI recommends one of the following procedures:
Purge the instrument down as low as possible.
Place the vent line in water and disconnect the sample.
Next, disconnect the vent line and place the range switch on the X100 range.
The unit should stay on the X100 range if there are no leaks.
Purge the instrument with Nitrogen at the sample port.
Note the reading once it has stabilized (at least 24 hrs. on the 0-10 ppm range) and
increase the flow rate.
If the reading goes down, the unit, or the tubing to the unit, has a leak.
PRODUCT SPECIFICATION DATA
0-10, 0-100, 0-1000, 0-10000 ppm Oxygen
CAL range for air calibration
0.5% of Full Scale
±2% of full scale (except ±1 ppm for 0-10 ppm range) at constant
temperature and pressure (temperature and pressure of calibration).
±5% of full scale (except ±1 ppm for 0-10 ppm range), over
operating temperature range (once temperature equilibrium has been
System Operating Temperature:
90% response time 61 seconds
±1% at constant temperature
System Power Requirements:
Model 311 - AC power for battery recharge circuit of two
current limited rechargeable NiCad batteries, 115 VAC,
50/60Hz (100/220 VAC optional).
6 lb (2.71 Kg.).
Intrinsically Safe (Class I, DIV. I, GROUP A, B, C and D), Factory
RECOMMENDED SPARE PARTS LIST
MICRO-FUSE, 0.25 AMP., FAST-BLOW
(FOR 210-240 VAC)
MICRO-FUSE, 0.25 AMP., FAST-BLOW
(FOR 100-125 VAC)
C6689 -B2C MICRO-FUEL CELL, CLASS B-2C
MICRO-FUEL CELL, CLASS A-2C (CO2 applications)
DIAL-RANGE OF 0-10, 0-100, 0-1000, 0-10000 PPM O2
& CAL. (USE WITH M70 METER)
A MINIMUM CHARGE IS APPLICABLE TO SPARE PARTS ORDERS.
SEND ORDERS TO:
Orders for replacement parts should include the part number (if available),
model number, serial number, sales order number, and range/background
of the analyzer for which the parts are intended.
TELEDYNE ANALYTICAL INSTRUMENTS
16830 CHESTNUT STREET
CITY OF INDUSTRY, CALIF. 91749
The MSDS on this material is available upon request through the Teledyne
Environmental Health and Safety Coordinator. Contact at (626) 934-1592.