Siemens SITRANS LUT400 Operating Instructions Manual page 245

Symptom
Reading fluctuates
while material level is
still
A5E33329501 SITRANS LUT400 (HART) – OPERATING INSTRUCTIONS
Cause
Material level is changing
Strong false echoes
Incorrect damping
Improper echo Algorithm selec-
tion
High noise levels
Weak echo
Foam on surface of material
Rapid temperature changes
Faulty temperature sensor
Vapours
Action
Visually verify, if possible.
Determine source of false echoes;
Relocate transducer to avoid
source.
Adjust damping. See Damping Fil-
ter (2.3.3.) on page 143.
Set algorithm to default. If no
improvement, try a different algo-
rithm. See Algorithm (2.12.2.1.) on
page 182.
Verify source and minimize. See
"Noise Problems" on page 242.
Determine cause;
Check noise, confidence, FOM,
and echo strength. See Echo
Quality (3.2.9.) on page 204.
Eliminate source of foaming;
Use stilling well.
Use an external temperature sen-
sor. See Temperature Source
(2.12.1.3.) on page 181.
Verify operation;
Replace if required, or use fixed
temperature. See Temperature
Source (2.12.1.3.) on page 181.
If fluctuation is unacceptable, con-
sider an alternative technology.
Contact your Siemens representa-
tive.
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