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Possible causes and recommended actions for excessive (saturated)
drive gain (continued)
Table 10-8:
Possible cause Recommended actions
Cavitation, flashing, or air en-
trainment; settling of two- or
three-phase fluids
• Increase the inlet or back pressure at the sensor.
• If a pump is located upstream from the sensor, increase the dis-
tance between the pump and sensor.
• The sensor may need to be reorientated. Consult the installa-
tion manual for your sensor for recommended orientations.
Drive board or module failure Contact Micro Motion.
Bent flow tube Check the pickoff voltages (see Section 10.27). If either of them are
close to zero (but neither is zero), the flow tubes may be bent. The
sensor will need to be replaced.
Cracked flow tube Replace the sensor.
Sensor imbalance Contact Micro Motion.
Mechanical binding at sensor Ensure sensor is free to vibrate.
Open drive or left pickoff sen-
sor coil
Contact Micro Motion.
Flow rate out of range Ensure that flow rate is within sensor limits.
Incorrect sensor characteriza-
tion
Verify the characterization parameters.
Erratic drive gain
Possible causes and recommended actions for erratic drive gain
Table 10-9:
Possible cause Recommended actions
Wrong K1 characterization constant for sensor Verify the K1 characterization parameter.
Polarity of pick-off reversed or polarity of drive reversed Contact Micro Motion.
Slug flow Check for slug flow. See Section 10.25.
Foreign material caught in flow tubes • Purge the flow tubes.
• Replace the sensor.
10.26.1 Collect drive gain data
ProLink II ProLink > Diagnostic Information
Field Communicator Service Tools > Maintenance > Diagnostic Variables
Troubleshooting
186 Micro Motion
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9739 MVD Transmitters