Micro Motion CDM100M, Configuration And Use Manual

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Possible causes and recommended actions for excessive (saturated)
drive gain
(continued)
Table 10-7:
Possible cause Recommended actions
Flow rate out of range Ensure that the flow rate is within sensor limits.
Incorrect sensor characteriza-
tion Verify the characterization or calibration parameters.
Erratic drive gain
Possible causes and recommended actions for erratic drive gain Table 10-8:
Possible cause Recommended actions
Two-phase flow Check for two-phase flow. See Section 10.23 .
Foreign material caught in sen-
sor tubes • Purge the sensor tubes.
• Replace the sensor.
10.24.1 Collect drive gain data
Drive gain data can be used to diagnose a variety of process and equipment conditions.
Collect drive gain data from a period of normal operation, and use this data as a baseline
for troubleshooting.
Procedure
1. Navigate to the drive gain data.
2. Observe and record drive gain data over an appropriate period of time, under a
variety of process conditions.
10.25 Check the pickoff voltage
If the pickoff voltage readings are unusually low, you may have any of a variety of process
or equipment problems.
To know whether your pickoff voltage is unusually low, you must collect pickoff voltage
data during the problem condition and compare it to pickoff voltage data from a period of
normal operation.
Possible causes and recommended actions for low pickoff voltage Table 10-9:
Possible cause Recommended actions
Cavitation or flashing; settling of
two-phase or three-phase fluids • Increase the inlet or back pressure at the sensor.
• If a pump is located upstream from the sensor, increase
the distance between the pump and sensor.
• The sensor may need to be reoriented or repositioned.
Consult the installation manual for your sensor.
Troubleshooting
164 Micro Motion ® Compact Density Meters (CDM)