Velocity measurement problems and recommended actions (continued)Table 10-4:
Problem Possible causes Recommended actions
Erratic non-zero ve-
locity 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 appro-
priate for your application (refer to the
sensor installation manual).
• Check the drive gain and the pickoff volt-
age. See Section 10.24 and Section 10.25.
• 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 con-
figured correctly for your application.
• Check for two-phase flow. See
Section 10.23.
• Check for radio frequency interference.
See Section 10.20.
• Contact Micro Motion.
Inaccurate velocity
reading
• Wiring problem
• Inappropriate measurement unit
• Incorrect flow calibration factor
• Incorrect density calibration factors
• Incorrect grounding
• Two-phase flow
• Problem with receiving device
• Incorrect sensor zero
• Verify that the measurement units are con-
figured correctly for your application.
• Verify all of the characterization or calibra-
tion parameters. See the sensor tag or the
calibration sheet for your meter.
• Zero the meter. See Section 2.4.
• Check the grounding of all components.
See Section 10.3.
• Check for two-phase flow. See
Section 10.23.
• Verify the receiving device, and the wiring
between the transmitter and the receiving
device.
• Replace transmitter.
Velocity switch trig-
gered erroneously
• Incorrect sensor zero • Zero the meter. See Section 2.4.
Troubleshooting
154 Micro Motion
®
Compact Density Meters (CDM)
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