Siemens Sitrans LR200 Instruction Manual page 132

Center
Uses center of the echo.
Hybrid
Uses the Center algorithm for the top part of the vessel, and the CLEF algorithm for the
part nearest the vessel bottom, according to the setting for CLEF range.
CLEF (Constrained Leading Edge Fit)
• Uses the leading edge of the echo.
• Is used mainly to process the echo from materials with a low dK value.
In an almost empty flat-bottomed vessel, a low dK material may reflect an echo weaker
than the echo from the vessel bottom. The echo profile shows these echoes merging. The
device may then report a material level equal to or lower than empty
The CLEF algorithm enables the device to report the level correctly.
Example: CLEF off: Position set to Hybrid
Vessel height: 1.5 m; CLEF range set to 0 (Center algorithm gives the same result.)
material
echo
echo marker
Page 124 SITRANS LR200 (HART) – INSTRUCTION MANUAL
default TVT
vessel
bottom
echo
selected
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