Liquid level indicators

Abstract

Abstract A LIQUID LEVEL INDICATOR, PARTICULARLY SUITABLE AS A TIDE GAUGE, INDICATES THE MEAN LEVEL OF A LIQUID. A NUMBER OF SENSING ELEMENTS, E.G. CAPACTIVE ELECTRODES OR DONCUTIVITY SENSORS, SPACED VERTICALY, SENSE THE PRESENCE OR ABSNCE OF LIQUID AT EACH ELECTRODE AND GIVE SIGNALS WHICH MAY BE CONVERTED TO A BINARY DIGITAL NUMBER INDICATING THE INSTANTANEOUS LEVEL. THIS DIGITAL OUTPUT SIGNAL CONTROLS A SERIES OF AND GATES TO PASS PULSES WHICH, FOR EACH GATE, ARE AT A RATE CORRESPONDING TO THE SIGNIFICANCE OF THE APPROPRIATE DIGIT. THE PULSES ARE NON-COINCIDENT PULSES OBTAINED BY DIVIDING DOWN THE OUTPUT OF AN OSCILLATOR. THE TOTAL NUMBER OF PULSES FROM ALL THE GATES OVER A PREDETERMINED PERIOD IS FED TO A COUNTER WHICH INDICATES THE MEAN LEVEL OVER THAT PERIOD. BY USING PULSE TRAINS, THE LEVEL IS AVERAGED OVER A PERIOD OF TIME ENABLING THE MEAN LEVEL TO BE DETERMINED TO AN ACCURACY BETTER THAN THE ELECTRODE SPACING.

Inventors

• 👤 James Stewart Johnston

Bibliographic Details