User's Manual

Page 94 SITRANS LR250 (HART) – INSTRUCTION MANUAL 7ML19985JE03
mmmmm
Parameters
2.8.7. TVT setup
2.8.7.1. Auto False Echo Suppression
Used together with Auto False Echo Suppression Range (2.8.7.2.) to screen
out false echoes in a vessel with known obstructions.
A ’learned TVT’ (time
varying threshold) replaces the default TVT over a specified range. See
Auto False Echo Suppression (2.8.7.1.) on page 130 for a more detailed
explanation.
a) Determine Auto False Echo Suppression Range. Measure the actual
distance from the sensor reference point to the material surface
using a rope or tape measure.
b) Subtract 0.5 m (20") from this distance, and use the resulting value.
Note: Default settings in the parameter tables are indicated with an asterisk
(*) unless explicitly stated.
Notes:
• Make sure material level is below all known obstructions when Auto
False Echo Suppression is used to learn the echo profile. (An empty or
almost empty vessel is recommended.)
• Note the distance to material level when Auto False Echo learns the
environment. Set Auto False Echo Suppression Range to a shorter
distance to avoid the material echo being screened out.
• Set Auto False Echo Suppression and Auto False Echo Suppression
Range during startup, if possible.
• If the vessel contains an agitator it should be running.
• Before adjusting these parameters, rotate the instrument for best
signal (lower false-echo amplitude).
Before Auto False Echo Suppression
default TVT
TVT
Hover
Level
Level (db)
echo marker
material level
false echo