Nozzle Mountings; Set The Sitrans Lut400 To Ignore The Bad Echo; If The Echo Is Close To The Transducer; Adjust The Tvt To Ignore The Echo - Siemens SITRANS LUT400 Operating Instructions Manual

11.7.2

Nozzle Mountings

If the transducer is mounted on or in a nozzle, grind smooth any burrs or welds on the inside
or open end (the end that opens into the vessel). If the problem persists, install a larger
diameter or shorter length nozzle, bevel the inside of the bottom end, or cut the open end of
the nozzle at a 45° angle.
See the transducer manual for complete mounting instructions.
If the mounting hardware is over tightened, loosen it. Over tightening changes the resonance
characteristics of the transducer and can cause problems.
11.7.3

Set the SITRANS LUT400 to Ignore the Bad Echo

If the preceding remedies have not fixed the problem, the false echo has to be ignored.
11.7.3.1

If the Echo is Close to the Transducer

If there is a static, incorrect, high level reading from the SITRANS LUT400 there is probably
something reflecting a strong echo back to the transducer. If the material level never reaches
that point extend the Near Range (2.2.4.) (Page 172) to a distance to just past the
obstruction.
11.7.3.2

Adjust the TVT to Ignore the Echo

Use Auto False Echo Suppression (2.12.3.1.) (Page 222). If this does not correct the
problem, use TVT Shaper (2.12.4.) (Page 223) to manually shape around false echoes.
11.8

Wrong Reading

If the Reading is erratic, or jumps to some incorrect value periodically, ensure the:
1. Surface monitored is not beyond the SITRANS LUT400's programmed range or the
transducer's maximum range.
2. Material is not falling into the transducer's acoustic beam.
3. Material is not inside the blanking distance (near range) of the transducer.
11.8.1

Types of Wrong Readings

If a periodic wrong Reading is always the same value, see Fixed Reading (Page 280).
If the wrong Reading is random, ensure the distance from the transducer to the material
surface is less than Far Range (2.2.5.) (Page 172) value plus one meter (i.e. ensure you are
still within the measurement range programmed in the device). If the material/object
monitored is outside this range, increase Far Range (2.2.5.) (Page 172) as required. This
error is most common in OCM applications using weirs.
SITRANS LUT400
Operating Instructions, 07/2019, A5E33329501-AC
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