Emerson Micro Motion 3711 Configuration And Use Manual page 185

Maintenance and Troubleshooting
Table 15-3 Process variables problems and possible remedies
Symptom
Steady non-zero flow rate under
no-flow conditions
Erratic non-zero flow rate under
no-flow conditions
Erratic non-zero flow rate when flow
is steady
Configuration and Use Manual
Cause
Misaligned piping (especially in new
installations)
Open or leaking valve
Bad sensor zero
Bad flow calibration factor
RF interference
Wiring problem
Incorrectly grounded 9-wire cable (in
remote core processor with remote
transmitter installations)
Vibration in pipeline at rate close to
sensor tube frequency
Leaking valve or seal
Inappropriate damping value
Slug flow
Plugged flow tube
Moisture in sensor junction box
Mounting stress on sensor
Sensor cross-talk
Incorrect sensor orientation
Problem with receiving device
Inappropriate damping value
Excessive or erratic drive gain
Slug flow
Plugged flow tube
Wiring problem
Possible remedy
Correct the piping.
Check or correct the valve mechanism.
Rezero the meter. See Section 5.6.
Verify characterization. See
Section 15.13.
Check environment for RF interference.
Verify all sensor-to-transmitter wiring
and ensure the wires are making good
contact.
Verify 9-wire cable installation. See the
Model 3711 installation manual.
Check environment and remove source
of vibration.
Check pipeline.
Check configuration. See Section 5.4.
See Section 15.12.
Check drive gain and tube frequency.
Purge the flow tubes.
Open junction box and allow it to dry.
Do not use contact cleaner. When
closing, ensure integrity of gaskets and
O-rings, and grease all O-rings.
Check sensor mounting. Ensure:
• Sensor is not being used to support
pipe.
• Sensor is not being used to correct
pipe misalignment.
• Sensor is not too heavy for pipe.
Check environment for sensor with
similar (±0.5 Hz) tube frequency.
Sensor orientation must be appropriate
to process fluid. See the installation
manual for your sensor.
Test with another receiving device.
Check configuration. See Section 5.4.
.
See Section 15.16.2
See Section 15.12.
Check drive gain and tube frequency.
Purge the flow tubes.
Verify all sensor-to-transmitter wiring
and ensure the wires are making good
contact.
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