ALTEC PH Service Manual

pH Sensor

ALTEC

Features double junction reference design for extended service life in
harsh applications.

1. SENSOR SPECIFICATIONS

pH Range: 0 - 14 pH
Bulb Glass:* HT-3(industrial grade)

HT-4(high pH> 12.0)
Gp (flat bu lb)

Temperature Range: *0 - 60°C
Pressure Range:* up to 150 psig

Signal Cable: Low Noise Coax, Dual Shielded

* Varies depending upon Model selected

2. PREPARATION FOR USE

1. Remove protective cap containing the storage solution (3.8 Molar KCI).

2. Save the protective cap for future use as a storage container and bulb protector when sensor is
not in service.
We recommend 3.8M KCI as the Storage solution.

3. For first-time use: Inspect the sens or for any signs of breakage or shipping damage and
commence with Calibration Procedures.

4. For s ensors with replaceable O-ring seals: All O-rings require proper lubricati on. We reco mmend
using PARKER OLUBE or equal for this purpose. Follow the instructions p rovided with lub ricant.
For best results we recomme nd th at al l O-rings be replaced whenever sensor is removed for
service or inspection.

CAUTION:

Hand-tighten only! It is n ot necessary to apply excessive torque to achieve a liquid tight
installation. Severe twisti ng o f th e sensor housing could cause internal damage. If necessary, use
a wrench for remov al onl y! For valve retractable sensors, refer to SA 877/SA878 Service Manuals
for assembly, installation, and complete service instructions .

3. CALIBRATION PROCEDURE

Refer to the specific instructions for pH sensor calibration described in the instruction manual
provided with the host pH instrument. These instructions will include procedures for automatic
and/or manual calibration. The ProcessProbe is d esigned to work wi th all quality pH in struments.
For best res ults it is recommended to perform a two-point pH calibration using tw o pH bu ffer

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pH Sensor

solutions in accordance with ASTM Method D1293, "Standard Test Methods for pH of Water".

Recommended Two-Point Calibration:

1. Rinse t he ProcessPro be thoroughly with D.I. water to remove all traces of storage solution,
process medium, or previous test solution to prevent "carry over" contamination of the pH buffer
test solutions. Thoroughly rinse the ProcessProbe with D.I. water after each buffer test.

2.Insert t he ProcessProbe in 7.0 pH buffer solution and momen tarily stir with sensor to e nsure
proper contac t. Allo w up to 10 minute s for integral T.C . devi ce to thermally equilibrate with the
buffer solution before taking a pH reading.
The pH reading sh ould be 7 .0 pH±0.33 pH (± 20 mV) @ 25°C. Ma ke any necessary adjus tments to
the pH meter with the "standardize" or "zero" control for a pH indication = 7.0 pH.

3. Rinse t he Proce ssProbe with D.I. water and insert in a 4.01 pH buffer solution. Stir with sensor
to ensure proper contact. Allow u p to 10 minutes for the integra l T.C. device to th ermally equilibrate
with the buffe r solu tion b efore taking a pH readi ng. Ma ke any necessary adjustments to the pH
meter with the "slope" or "span" control for a reading 4.01 =pH units.

ALTEC

NOTES:

●Always use "fresh" pH buffer solutions for best results.

●PH buffer solutions above 7.0 pH are less stable and ha ve a very limited li fe.
These high pH buffers will more r eadily absorb CO from the atmosphere and will typically change

to a lower pH value when left open.

●Keep in mind that the "older" a sensor becomes, it will exhibit slower respons e times and will
become less efficient in terms of its ability to span several pH units wit h the same repeata bility.

●pH sensors are imper fect devices and require "calibration" fr om time to time in order to be
properly characterized to the host pH meter.

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4. GRAB SAMPLE CALIBRATION

1. Grab samp le calibration of a pH sensor is more vali d when the se nsor has been previously
"characterized" to its pH meter via the two-point pH buffer calibration proced ure. The grab sample
technique will evaluate the pH senso r's performanc e under actual operating conditions which d iffer
from the pH buffer calibration conditions previo usly seen by the sen sor.

2. For a proper grab sample technique, a known good labora tory p H sensor and pH met er tha t are
in calibration with each other are required equipment. The laboratory pH s ensor should be ex­posed to the grab sample at t he identical temperature that the on-stream pH sensor encounters
in service.

3. No two pH sen sors are identical, therefore, exact pH readings are rarely achieved. The on­stream pH sensor has been conditioned to the process environment and may report the process
pH m ore accurately than a laborat ory pH sensor which has no t yet totally acclimated to the process

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