Emerson Rosemount 5408 Reference Manual page 110

Service and troubleshooting
February 2020
Table 7-6: Incorrect Level Readings
(1)
Symptom
Measured value jumps to a lower value.
Measured level fluctuates.
Measured level is occasionally unstable.
Measured level lags during rapid level
changes.
110
(continued)
Possible causes
Multiple products in the tank,
e.g. thin oil layer on top of
water that is sometimes
detected, sometimes not.
Time
Excessive foaming or
turbulence.
Time
May be caused by an empty
tank with the amplitude
threshold set too low.
The product surface is close
to a suppressed false echo.
Time
Damping value too high.
Maximum Level Rate value
too low.
Time
Reference Manual
00809-0100-4408
Recommended actions
Set Double Surface Handling to Track
Upper Surface or Track Lower Surface, see
Double surface handling.
• Under turbulent conditions with low
level rates, consider increasing the
Damping value, see Damping
• Enable the Foam parameter or
Turbulent Surface parameter, or both.
See Process conditions.
Analyze the echo curve and check
amplitude thresholds, see Amplitude
thresholds.
If possible, remove the disturbing object.
If there is a problem with lag during rapid
level changes, consider decreasing the
Damping value, see Damping
Verify Maximum Level Rate configuration.
value.
value.
Reference Manual