Emerson Micro Motion, Installation Manual

Page: 47 / 74

Micro Motion
®
Model D and DT Sensors Instruction Manual 43
Troubleshooting
continued
Erratic flow rate
Symptom
The flowmeter indicates the flow rate is varying, even though it is steady.
Troubleshooting instructions
To troubleshoot an erratic flow rate, you will need one of the
communications devices listed on page 46 or a transmitter with a
display. Refer to the table below for the necessary steps to troubleshoot
an erratic flow rate.
Table 2. Troubleshooting erratic flow rate
Procedure Instructions What to do next
1. Check for erratic flow rate at the
transmitter See page 47 • If the signal is stable at the transmitter, go to step 2
• If the signal is erratic at the transmitter, go to step 4
2. Check for faulty output wiring See page 47 • If the output wiring is OK, go to step 3
• If the output wiring is faulty, repair or replace it, then go to
step 13
3. Check the receiving device for
malfunctions See instruction
manual for the device • If the receiving device is OK, go to step 4
• If the receiving device is faulty, contact the manufacturer
4. Check the flow units See page 46 • If the flow units are OK, go to step 5
• If the flow units are wrong, change them, then go to step 13
5. Check the damping value See page 50 • If the damping value is OK, go to step 6
• If the damping value is too low, change it, then go to step 13
6. Check for stable drive gain See page 50 • If the drive gain is stable, go to step 7
• If the drive gain is not stable, go to step 11
7. Check for a stable density reading See page 50 • If the density reading is stable, go to step 8
• If the density reading is not stable, go to step 11
8. Check for faulty or improperly
installed flowmeter wiring See page 47 • If the flowmeter wiring is OK, go to step 9
• If the flowmeter wiring is incorrect or faulty, fix or replace it,
then go to step 13
9. Check for faulty or improperly
installed grounding See page 51 • If the grounding is OK, go to step 10
• If the grounding is incorrect or faulty, fix it, then go to step 13
10. Check for vibration or crosstalk See page 53 • If there is no vibration or crosstalk, go to step 11
• If there is vibration or crosstalk, eliminate it, then go to
step 13
11. Check for two-phase flow See page 53 • If there is no two-phase flow, go to step 12
• If there is two-phase flow, fix the problem, then go to step 13
12. Check for plugging or build-up on
the sensor flow tubes See page 54 • If the tubes are not plugged, go to step 14
• If there is plugging or build-up, clear the tubes, then go to
step 13
13. Check again for erratic flow rate See page 47 • If the signal is no longer erratic, you’ve solved the problem
• If the signal is still erratic, start over at step 1 or go to step 14
14. Contact Micro Motion Phone numbers are
listed on page 41