Gauging system providing remote readout of liquid levels in gasoline storage tanks

Abstract From the Canadian patent

Abstract:, A controller at a monitor location generates interrogate signals which are transmitted over a telephone line to a transmitting unit associated with a plurality of underground gasoline storage tanks, The transmitting unit responds to the interrogate signals to selectively couple pressure sensing lines to a pressure sensing transducer. Each line extends into a different one of the storage tanks and provides a pressure which is proportional to the depth of the liquid in the corresponding tank. As each line is coupled to the transducer in sequence the, transducer provides an output voltage corresponding to the sensed pressure. The output voltage controls a transmitter of the …