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Ultrasonic probes in tanker
Page 64
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ASPECIALIZED road tanker, built to carry an exceptionally highly volatile liquid used in the manufacture of foam rubber, has recently been completed by Darham Industries Ltd. An unusual feature of the vehicle is the use of ultrasonic probes to determine the load level within the tank. This system was adopted to ensure that there was no likelihood of spillage during loading operations, and that when unloading it was possible to maintain a level above the exhaust valve of the vessel, so preventing internal contamination.
A problem was presented by the extremely ' high viscosity of the liquid carried, in that drainage from the sensing device would be slow. After a series of laboratory tests the Sonac probes—which were supplied by Westool Ltd., of Bishop Auckland, Co. Durham—were shown to give a dependable signal under all conditions of operation.
The high-level probe gives a visual signal on the control panel mounted in the driver's cab and the low-level probe cuts off the tank exhaust valve as soon as the liquid falls below the diaphragm.
The sensor cables terminate in sockets so that the amplifier can be used for both highand low-level control. A pair of ganged switches set the circuit for correct operation and warning lights monitor the findings of the sensing units.