Yokogawa Instruction Sheet Model PH97 pH Sensor
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PREPARATION FOR USE:
1. Remove storage boot containing the
storage solution (3.8M KCl) by unwinding the black sealing tape from the sensor housing.
DO NOT remove the wetted fiber pack
from inside the storage boot.
2. Save the storage boot with fiber pack
for future use as a storage container
and bulb protector when sensor is not in
service. Be certain to use 3 to 4 M KCl
as the storage solution. Seal boot to
sensor with black electrician’s tape
using 3 to 5 complete wraps.
3. For first-time use after removing the
storage boot: Inspect the sensor for any
signs of breakage or shipping damage
and commence with Calibration Procedures.
4. For sensors with replaceable o-ring
seals: All o-rings require proper lubrication. We recommend use of PARKER O
LUBE or equal for this purpose. Follow
the instructions provided with lubricant.
For best results we recommend that all
o-rings be replaced whenever sensor is
removed for service or inspection.
Yokogawa Corporation of America
2 Dart Road, Newnan, GA 30265
Tel.: 770-254-0400 Fax.: 770-251-6427
Doc. Nr. L2530
The Model PH97/DP pH sensor is designed for use only with the Model PH87
retractable assembly. Please refer to the
Model PH87 retractable assembly installation manuals for complete assembly,
installation, and service instructions.
Refer to the specific instructions for pH
sensor calibration described in the
instruction manual provided with the
EXA pH analyzer. These instructions will
include procedures for automatic and/or
For best results it is recommended
to perform a two-point pH calibration
using NIST primary buffers.
Rinse the probe thoroughly with DI
water to remove all traces of storage
solution, process medium or previous
test solution to prevent “carry over” contamination of the pH buffer solutions.
Thoroughly rinse the probe with DI
water after each buffer test.
• Always use “fresh” pH buffer solutions
for best results.
• pH buffer solutions above 7.0 pH are
less stable and have a very limited life.
These high pH buffers will more readily
absorb CO2 from the atmosphere and
will typically change to a lower pH value
when left open.
• Keep in mind the the “older” a sensor
becomes, it will exhibit slower response
times and will become less efficient in
terms of its ability to span several pH
units with the same repeatability.
CLEANING A MODEL PH 97/DP
WITH IMPAIRED RESPONSE:
Used pH sensors which are physically
intact can sometimes be restored to an
improved level of performance. All pH
sensors have a given useful life span
depending on the conditions of use. One
of the following procedures may prove
helpful in restoring a used pH sensor.
1. Initial Cleaning: Wash with a solution of liquid detergent or enzyme detergent and warm water by gently scrubbing with a soft toothbrush or soft tissue.
Follow with thorough rinse in DI or clean
2. Inorganic Scale Deposits: Dissolve
the deposit by immersion of the sensor’s
measurement tip in dilute hydrochloric
acid for a few minutes. Repeat step #1
3. Organic Oil or Grease Films: Perform initial cleaning procedure. If film is
known to be soluble in a particular organic solvent, wash with this solvent.
Repeat step #1 above. Depending on
the extent of the oil or grease contamination, it’s possible that the liquid junction may be damaged beyond recovery.
Soak in 3 to 4M KCl solution for a minimum of 30 minutes before recalibration
and returning sensor to service.
4. Plugged or Dry Liquid Junction:
Remove any observed contaminant with
one of the above procedures, then soak
in 3 to 4M KCl solution for a minimum of
• Never permit the pH sensor to dehydrate or dry-out. Always keep it in a wetted environment especially when not in
• Cracked or broken sensors are not
• Inspect cable and connector to ensure that the insulation integrity is intact
and that there are no signs of corrosion
or contaminants on the metal components.
1. Short Term: Immerse sensor measurement tip and liquid junction surface
areas in 3 to 4M KCl. If this solution is
not available, use 4.01 pH buffer, clean
tap water, or lastly, a sample of the process being measured to keep the sensor hydrated.
2. Long Term: Fill storage boot that the
sensor was originally shipped in with a
freshly prepared 3 to 4M KCl solution
and insert sensor. Seal boot to sensor
with black electrician’s tape using 3 to 5
complete wraps. The sensor should be
stored in an upright (vertical) position.
Model PH97 pH Sensor with
Extension cable may be purchased in bulk
quantities. In the case of bulk quantities, cut to
length, then terminate the cable as shown
24" or 36"
NOTE: With the
ORP option there
are no TC cables #1
Termination procedures for WF10 cable
1. Slide 3 cm of the heat shrink tube (9 x 1.5)
over the end of the cable to be terminated.
2. Strip 9 cm of the outer (black) insulating
materials, taking care not to cut or damage
0.9 " O.D.
Connect WF10 cables 11-15
to junction box terminals 1-5,
respectively. Cables 16 and 17
of the extension cable are NOT
connected at the junction box,
and should be terminated and
taped. Connect cables 11-17 to
the appropriately labeled terminals
in the analyzer.
®DynaProbe is a registered trademark of
and manufactured by Broadley-James
Corporation. U.S. Patent 5,147,524
3. Remove loose copper screening and cut the
cotton packing threads as short as possible.
Use WF10 extension cable from
the junction box to the analyzer or
transmitter. Do no exceed 30 meters
(100 ft) between the sensor and the
4. Strip insulation from the last 3 cm of the
brown and the white coaxial cores.
YOKOGAWA CORPORATION OF AMERICA
2 Dart Road
Newnan, GA 30265-1040
Dome pH Bulb
-5000 mV to 5000 mV
(requires/ORP option which
replaces pH bulb)
100 psig @ 212˚F (100˚C)
10 feet per second
(3 meters per second)
Dome pH bulb:
Platinum (/ORP option)
Standard cable length:
5. Extract the coaxial cores from the braid,
and trim the black (low-noise) screening
material as short as possible.
All rights reserved. Copyright © 2000.
Yokogawa Corporation of America.
6. Insulate the overall screen and the 2 coaxial
screens with suitable plastic tubing.
7. Strip and terminate all ends with suitable
(crimp) terminals and identify with numbers
24” (terminated in J-box)
36” (terminated in J-box)
8. Finally, shrink the heat shrink tube into position.