c. Place the end of the tubing in a 5 mL graduated cylinder.
d. Start the reagent pump and collect reagent for ten minutes.
e. Note the volume of reagent collected in the graduated cylinder. After ten
minutes, the volume should be about 2 mL.
Figure 13-1: Disconnecting Sample (A) and Reagent (B) Tubing Prior to Checking Flow
13.5.2 Process readings are erratic or wander
1. Is the sensor properly wired to the transmitter? See Wiring. Verify that all
connections are tight.
2. Readings can be erratic when a new sensor is first placed in service. Readings
usually stabilize after about an hour.
3. Is the air pump working? There should be a vigorous stream of bubbles in the flow
cell. The bubbles help mix the sample and keep carbon dioxide bubbles off the
membrane. Carbon dioxide forms when bicarbonate alkalinity in the sample reacts
with acetic acid. The bubbles accumulate in the membrane and eventually break
away, causing the total chlorine reading to wander.
4. Is the membrane damaged or loose? Replace the membrane if necessary.
5. Is the space between the membrane and cathode filled with electrolyte solution, and
is the flow path between the electrolyte reservoir and membrane clear? Often the
flow of electrolyte can be started by simply holding the sensor with the membrane
end pointing down and sharply shaking the sensor a few times as though shaking
down a clinical thermometer. If shaking does not work, try clearing the holes around
Troubleshoot Reference Manual
January2023 00809-0200-3415
68 Emerson.com/Rosemount
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