Emerson Rosemount TCL, Manual

Page: 80 / 108

6. Slide the replacement board partially into the board slot. Plug the sensor board into
the main board and reattach the sensor wires.
7. Carefully pull the sensor cable through the gland fitting as you push the sensor
board back into the enclosure.
8. Close the front panel.
9. Turn on power.
10.2 Total chlorine sensor
10.2.1 General
When used in clean water, the total chlorine sensor requires little maintenance. Generally,
the sensor needs maintenance when the response becomes sluggish or noisy or when
readings drift following calibration. Maintenance frequency is best determined by
experience. For a sensor used in potable water, expect to clean the membrane every
month and replace the membrane and electrolyte solution every three months.
10.2.2 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.
10.2.3 Replacing the membrane
Complete the following steps to replace the membrane on the total chlorine sensor.
1.
Hold the sensor with the membrane facing up.
2. Unscrew the membrane retainer. Remove the membrane assembly and O-ring.
See Figure 10-2 .
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 carbon
finishing paper. Rinse the cathode thoroughly with water.
4. 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. Set aside.
5. Put a new O-ring in the groove.
6. Place a drop of electolyte solution on the cathode. Invert the membrane assembly
and place it over the cathode stem.
7. Screw the membrane retainer back in place.
8. Hold the sensor with the membrane pointing down. Shake the sensor a few times,
as though shaking down a clinical thermometer.
Maintenance
72 Rosemount TCL