Table 17-7: Velocity measurement problems and recommended actions
(continued)
Problem
Possible causes
Recommended actions
Erratic non-zero
flow rate
at no-flow conditions
•
Leaking valve or seal
•
Two-phase flow
•
Plugged or coated sensor tube
•
Incorrect sensor orientation
•
Wiring problem
•
Vibration in pipeline at rate close to sensor
tube frequency
•
Damping value too low
•
Mounting stress on sensor
•
Verify that the sensor orientation is
appropriate for your application. See the
installation manual for your sensor.
•
Check the drive gain and the pickoff
voltage.
•
Purge the sensor tubes.
•
Check for open or leaking valves or seals.
•
Check for sources of vibration.
•
Verify damping configuration.
•
Verify that the measurement units are
configured correctly for your application.
•
Check for two-phase flow.
•
Check for radio frequency interference.
•
Contact customer service.
Erratic non-zero
velocity reading when
velocity is steady
•
Two-phase flow
•
Damping value too low
•
Plugged or coated sensor tube
•
Output wiring problem
•
Problem with receiving device
•
Wiring problem
•
Verify that the sensor orientation is
appropriate for your application. See the
installation manual for your sensor.
•
Check the drive gain and the pickoff
voltage.
•
Check for air entrainment, tube fouling,
flashing, or tube damage.
•
Purge the sensor tubes.
•
Check for open or leaking valves or seals.
•
Check for sources of vibration.
•
Verify damping configuration.
•
Verify that the measurement units are
configured correctly for your application.
•
Check for two-phase flow.
•
Check for radio frequency interference.
•
Contact customer service.
Troubleshooting
Configuration and Use Manual
March 2019
MMI-20025166
306
Micro Motion Model 5700 Transmitters with Configurable Outputs