Sludge Measurement System Thrives in Extreme Temperatures

Sept. 6, 2002

Solartron Mobrey's MSL600 system recently was tested as part of an evaluation process conducted by Toronto, Canada's Highland Creek sewage treatment plant managers. After careful analysis of the results, they determined the MSL600 sludge level monitoring system installed on trial at the plant performed without problem even at temperatures as low as -28°C.

The system is used for sludge control on the plant's primary settlement tank. The ultrasonic transducer unit, suspended in the supernatant, transmits an ultrasonic pulse, which is reflected off the sludge blanket. The time of flight of the echo determines the height of the blanket to an accuracy of ±25mm.

The blanket level measurement and a graphical display of the sludge blanket are displayed continuously on the control unit, located in the plant?s control room, as the bridge traverses the tank. A wireless radio telemetry link between the bridge mounted control unit and the control room based receiver allows the process to be monitored and controlled at a distance without having to install expensive cable.

Herb Kershaw, president of BEP Bestobell Limited, Solartron Mobrey's Canadian distributor, explains: "The system installed at Highland Creek STW has a self-cleaning ultrasonic transducer. The extreme conditions could have presented the system with problems, but the self-cleaning mechanism has not been hampered by the low temperature at all."

Fouling of the sensor face in the hostile environment of the sludge tank is prevented by an innovative air-purge system which cleans the face of debris at regular, user-programmable intervals. Much more effective than mechanical cleaning devices--which can themselves easily become fouled--the MSL600 air purge system maintains the reliability and accuracy of the measurement.

A member of The Roxboro Group, Solartron Mobrey manufactures measurement and control sensors, offering an extensive range of level, flow, pressure, density, viscosity and other measurement solutions.