Radar level for cement maker
26 Jul 2006
Silo measurement device used to monitor material with very low dielectric constant
Wellingborough, UK — Concrete products supplier Xella has installed a Krohne Optiflex TDR radar meter for the level measurement of a virtually non-conductive powder material at its factory in Germany. The device has been fitted in a 15-metre-high silo containing a powder material used in the manufacture of dry lining boards.
The problem for Xella was that the material, called Perlite, has a dielectric constant of just 1.16; too low for conventional 2-wire TDR level meters, which typically measure only down to a dielectric constant of 1.5.
The Optiflex unit can detect return signals from the end of the probe even with materials of poor surface reflectivity. It then calculates the level of the material from the time taken to detect the signal emitted from the probe.
Pulse transit time depends on the dielectric constant of the material, so the instrument can accurately calculate the surface level of any material once this value is programmed into the unit, explains Krohne.
