Emerson Rosemount FCL, Reference Manual

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9.3.13 Broken Glass
The sensing element in the pH sensor is a thin glass membrane. Normally, the impedance
of the glass membrane is about 80 - 100 MΩ. If the glass membrane gets broken or
cracked, the impedance drops to less than 10 MΩ.
Procedure
1. Check sensor settings under the Measurement submenu. Confirm that the
preamplifier location is set to transmitter.
2. Confirm that the pH sensor is installed in the flow cell and sample is flowing through
the cell.
3. Check the sensor response in two buffers having different pH values.
If the membrane is cracked or broken, the pH reading will be about the same in
both buffers.
4. Replace the pH sensor.
9.4 Troubleshooting when a Warning message is
showing
Warning message Explanation Section
Sensor No solution Gnd pH sensor may be miswired. Sensor No Solution Gnd
Sensor Need Factory Cal The sensor board was not calibrated at
the factory. Sensor Need Factory Cal
Sensor Out of Range The pH measurement is invalid. Sensor Out of Range
Sensor Negative Reading The chlorine reading is less than -0.5
ppm. Sensor Negative Reading
Sensor RTD Sense Open RTD sensor line is broken or not
connected. Sensor RTD Sense Open
Sensor Temperature High Temperature is greater than 155 °C
(311 °F). Sensor Temperature High or Low
Sensor Temperature Low Temperature is less than -20 °C (-4 °F). Sensor Temperature High or Low
Broken Glass Disabled Advisory only (applies to pH sensor
only). Broken Glass Disabled
9.4.1 Sensor No Solution Gnd
This message implies that the pH sensor is miswired. Check sensor wiring.
9.4.2 Sensor Need Factory Cal
The sensor board was improperly calibrated at the factory. Call the factory for assistance.
Reference Manual Troubleshoot
00809-0100-3412 May 2019
Rosemount FCL 1056 91