Emerson Rosemount 5408 Reference Manual page 100

Service and troubleshooting
June 2019
Table 7-11: Incorrect Level Readings
(1)
Symptom
Level is stuck in measuring range.
Level is stuck in full tank.
100
(continued)
Possible causes
Incorrect alignment of the
transmitter.
Disturbing objects in the
tank.
Time
Disturbing objects near the
antenna.
Time
Product build-up on the
antenna.
Cone antenna does not
extend below the nozzle.
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Recommended actions
• Verify the transmitter head is correctly
aligned, see Align transmitter
• Use the suppress false echoes function
to manage strong disturbance echoes,
see Suppressing false echoes.
• Analyze the echo curve and check
amplitude thresholds, see
thresholds.
• Remove the disturbing object.
• Change alignment of transmitter head
in steps of about 15 degrees, see
transmitter head. After each step,
check if impact of disturbing echoes is
decreased using the echo curve.
• Put an inclined metal plate on top of
the disturbing object.
• Move the transmitter to another
position. Refer to Installation
considerations for installation
considerations.
• Use the suppress false echoes function
to manage strong disturbance echoes,
see Suppressing false echoes.
• Analyze the echo curve and check
amplitude thresholds, see
thresholds.
• For process seal antenna installed in a
nozzle taller than 10-in. (25 cm), adjust
the pre-configured amplitude
threshold, see Handling disturbances at
top of tank.
• Increase the Upper Null Zone, see
Handling disturbances at top of
• Remove the disturbing object.
• Move the transmitter to another
position. Refer to Installation
considerations for installation
considerations.
• Clean the antenna.
• Use transmitter with air purging
connection.
Use the extended cone antenna.
head.
Amplitude
Align
Amplitude
tank.
Reference Manual