Siemens SITRANS LUT400 - Page 276

SITRANS LUT400
274 Operating Instructions, 07/2019, A5E33329501-AC
Symptom
Possible Cause
Action
Weak echo Determine cause; Check noise, confidence,
FOM, and echo strength. See Echo Quality
(3.2.9.) (Page 244).
Foam on surface of mate-
rial
Eliminate source of foaming; Use stilling well.
Rapid temperature
changes
Use an external temperature sensor. See
Temperature Source (2.12.1.3.) (Page 218).
Faulty temperature sensor Verify operation;
Replace if required, or use fixed temperature.
See Temperature Source (2.12.1.3.)
(Page 218).
Vapours If fluctuation is unacceptable, consider an
alternative technology. Contact your Siemens
representative.
Reading is fixed, but
material level changes
or reading does not
follow material level
Incorrect speed of re-
sponse
Verify response speed setting is adequate for
process. See Quick Start (Page 59) (set in the
Quick Start Wizard).
Loss of Echo condition
(LOE)
Check Noise, Echo Strength, Confidence.
See Echo Quality (3.2.9.) (Page 244).
Check LOE Timer is not set too short. See
LOE Timer (2.4.2.) (Page 175).
Agitator blade stopped in
front of transducer (false
echo)
Ensure agitator is running.
Foam on surface of mate-
rial
Eliminate source of foaming. Use stilling well
Incorrect Algorithm used Set algorithm to default. If no improvement,
try a different algorithm. See Algorithm
(2.12.2.1.) (Page 220).
Transducer mounting:
wrong location or incor-
rectly mounted
Ensure beam has a clear path to material
surface;
Verify transducer is not too tight;
Use an isolation coupling.
Incorrect transducer used
for the application
Use correct transducer. Contact your Sie-
mens representative.
Unavoidable false echoes
from obstructions
Relocate transducer to ensure beam has a
clear path to material surface;
Use manual TVT shaping or Auto False Echo
Suppression. See TVT Shaper (2.12.4.)
(Page 223) or
Auto False Echo Suppression
(2.12.3.1.) (Page 222).
Accuracy Varies Faulty temperature sensor Verify operation; Replace if required, or use
fixed temperature. See Temperature Source
(2.12.1.3.) (Page 218).
Vapours present in vary-
ing concentrations
Eliminate vapours or consider a different
technology. Contact your Siemens repre-
sentative.
Thermal gradients Insulate vessel;
Consider external temperature sensor.