Other Troubleshooting - Chlorine - Emerson Rosemount FCL Reference Manual

Reference Manual
00809-0200-3412
9.5

Other troubleshooting - chlorine

Although calibration troubleshooting information is available in the transmitter by
pressing INFO, troubleshooting information for process measurement problems is not.
Problem
Process readings are erratic.
Readings drift.
Sensor does not respond to changes in chlorine level.
9.5.1 Process readings are erratic or wander.
Recommended actions
1. Make sure the sensor is properly wired to the transmitter. Verify that all connections
2. If the sensor is new, wait about an hour for readings to stabilize.
3. Make sure the air pump is working.
4. Check to see if the membrane is damaged or loose. Replace the membrane if
5. Make sure the space between the membrane and cathode is filled with electrolyte
6.
9.5.2 Readings drift.
Recommended actions
1. Check to see if the sample temperature is changing.
Rosemount FCL 56
are tight.
Readings can be erratic when a new sensor is first placed in service.
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.
necessary.
solution and the flow path between the electrolyte reservoir and membrane is clear.
Try starting the electrolyte flow by holding the sensor with the membrane end
pointing down and sharply shaking the sensor a few times as though shaking down
a clinical thermomemter.
Membrane permeability is a function of temperature. The transmitter automatically
corrects for changes in sensor current caused by temperature changes. The time
constant for the Rosemount
the reading may drift for a while after a sudden temperature change.
™
499ACL-02 sensor is about five minutes. Therefore,
Troubleshoot
May 2019
See Section
Process readings
are erratic or
wander.
Readings drift
Sensor does not
respond to
changes in
chlorine level.
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