Emerson Micro Motion LNG Series, Руководство по конфигурации и использованию

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10.3 Flow measurement problems
Flow measurement problems and recommended actions Table 10-2:
Problem Possible causes Recommended actions
Non-zero flow reading
at no-flow conditions
or at zero offset • Misaligned piping (especially in new instal-
lations)
• Open or leaking valve
• Incorrect sensor zero
• If the reading is not excessively high, re-
view the live zero. You may need to restore
the factory zero.
• Check for open or leaking valves or seals.
• Check for mounting stress on the sensor
(e.g., sensor being used to support piping,
misaligned piping).
• Contact Micro Motion.
Erratic non-zero flow
rate at no-flow condi-
tions • 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 appro-
priate for your application (refer to the
sensor installation manual).
• Check the drive gain and the pickoff volt-
age.
• If the wiring between the sensor and the
transmitter includes a 9-wire segment,
verify that the 9-wire cable shields are cor-
rectly grounded.
• Check the wiring between the sensor and
the transmitter.
• For sensors with a junction box, check for
moisture in the junction box.
• 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.
• Check for radio frequency interference.
• Contact Micro Motion.
Troubleshooting
Configuration and Use Manual 75