Emerson Rosemount 3308 Series Reference Manual page 116

Service and troubleshooting
February 2020
Table 6-6: Incorrect level readings
Symptom
Level stuck in measuring range.
Level stuck in empty.
Level fluctuations (a couple of inches).
Table 6-7: Incorrect or missing interface level reading
Symptom
Incorrect Interface Level reading.
Missing Interface Level reading (reported as NaN).
There are two products in the tank, but only the product
surface or interface is detected.
There are two products in the tank, but no readings are
reported.
116
(continued)
Possible cause and recommended actions
• May be caused by a disturbing object in the tank. Read
the Echo Curve and adjust Thresholds, see
thresholds.
• Check if the probe is bent and in contact with the tank
wall. This contact causes a false echo reading.
• Heavy coating or contamination on the probe. Clean
the probe.
• Thresholds may be too high, see
• There is too much disturbing noise in the tank (from
foam, splashing etc.). Set the Performance Mode to
High to get a stable measurement signal, refer to
Resolve noise or weak surface
• There are rapid level changes in the tank. Select a faster
Update Rate, refer to
• Thin oil layer on top of water that is sometimes
detected, sometimes not. Set the Peak Detection
Method to Threshold Intersection to improve the
stability of level measurements in such applications.
Refer to
Possible cause and recommended actions
• The Upper Product Dielectric Constant is not correct,
see
• Air gap is too big when the Measurement Mode is set to
Interface Level with Submerged Probe. Reduce air gap
or switch the Measurement Mode to Product Level and
Interface Level.
• The Measurement Mode is set to Product Level. Set
Measurement Mode to Product Level and Interface
Level, refer to
• The Interface Peak is difficult to detect, because the
bottom product has a low dielectric constant, or the
signal is attenuated in the upper product. Check
Thresholds. For more information, see
Interface peak not
• The upper product is too thin to be detected. No action
is needed. See
interface thickness for different probe types.
• Check Thresholds, see
• Check Thresholds, see
echoes.
Configure update
Resolve thin oil layers.
Upper product dielectric constant.
Measurement mode.
found.
Interface measurements
Adjust thresholds.
Adjust thresholds.
Reference Manual
00809-0100-4308
Adjust
Adjust thresholds.
rate.
Example 2:
for minimum
Rosemount 3308 Series