Checking Process Variables - Emerson Micro Motion 4200 Configuration And Use Manual

Troubleshooting
April 2019
Excessive (saturated) drive gain
Table 15-1: Possible causes and recommended actions for excessive (saturated) drive gain
Possible cause
Bent sensor tube
Cracked sensor tube
Flow rate out of range
Open drive or pickoff
sensor coil
Over-pressurized tubes
Plugged sensor tube
Sensor case full
of process fluid
Sensor imbalance
Sensor tubes
not completely full
Two-phase flow
Vibrating element
not free to vibrate
Erratic drive gain
Table 15-2: Possible causes and recommended actions for erratic drive gain
Possible cause
Foreign material
caught in sensor tubes

15.30 Checking process variables

Micro Motion suggests that you make a record of the process variables listed below, under normal operating
conditions. This list will help you recognize when the process variables are usually high or low.
• Flow rate
• Density
• Temperature
• Tube frequency
• Pickoff voltage
• Drive gain
198
Recommended actions
Check the pickoff voltages (see
zero (but neither is zero), the sensor tubes may be bent. The sensor will need to be
replaced.
Replace the sensor.
Ensure that the flow rate is within sensor limits.
Contact customer support.
Contact customer support.
Check the pickoff voltages (see
zero (but neither is zero), plugged tubes may be the source of your problem. Purge the
tubes. In extreme cases, you may need to replace the sensor.
Replace the sensor.
Contact customer support.
Correct process conditions so that the sensor tubes are full.
Check for two-phase flow. See
Ensure that the vibrating element is free to vibrate.
Recommended actions
• Purge the sensor tubes.
• Replace the sensor.
Check the pickoff voltage). If either of them are close to
Check the pickoff voltage). If either of them are close to
Check for two-phase flow (slug
Configuration and Use Manual
MMI-20048166
flow).
Micro Motion 4200 Transmitters