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MODEL TCL SECTION 12
MAINTENANCE
FIGURE 12-2. Detail of Front Panel of 54eA Controller
12.2 TOTAL CHLORINE SENSOR
12.2.1 General
When used in clean water, the total chlorine sensor
requires little maintenance. Generally, the sensor
needs maintenance when the response becomes slug-
gish or noisy or when readings drift follow calibration.
Maintenance frequency is best determined by experi-
ence. If the sensor is a used in potable water, expect to
clean the membrane every month and replace the
membrane and electrolyte solution every three months.
Sensors used in dirty water require more frequent
maintenance and calibration. However, if experience
shows the sensor is holding calibration and not drifting
appreciably between calibration intervals, the mainte-
nance interval can be extended.
12.2.2 Cleaning the membrane.
Keep the membrane clean. Clean the membrane with
water sprayed from a wash bottle. Use a soft tissue to
gently wipe the membrane.
12.2.3 Replacing the membrane.
1. Hold the sensor with the membrane facing up.
2. Unscrew membrane retainer. Remove the mem-
brane assembly and O-ring. See Figure 12-3.
3. Inspect the cathode. If it is tarnished, clean it by
gently rubbing in the direction of the existing
scratches (do not use a circular motion) with 400-
600 grit silicon carbide finishing paper. Rinse the
cathode thoroughly with water.
4. Put a new O-ring in the groove. Hold the mem-
brane assembly with the cup formed by the mem-
brane and membrane holder pointing up. Fill the
cup with electrolyte solution.
5 Next, place a drop of electrolyte solution on the
cathode. Invert the membrane assembly and place
it over the cathode stem.
6. Screw the membrane retainer back in place.
7. Hold the sensor with the membrane pointing down.
Shake the sensor a few times, as though shaking
down a clinical thermometer.
12.2.5 Replacing the membrane and electrolyte
solution.
1. Unscrew the membrane retainer and remove the
membrane assembly and O-ring. See Figure 12-3.
2. Hold the sensor over a container with the cathode
pointing down.
3. Remove the fill plug and allow the electrolyte solu-
tion to drain out.
4. Wrap the plug with several turns of pipe tape and
set aside.
5. Prepare a new membrane. Hold the membrane
assembly with the cup formed by the membrane
and membrane holder pointing up. Fill the cup with
electrolyte solution.
CAUTION
Fill solution may cause irritation.
Avoid contact with skin and eyes.
May be harmful if swallowed.