Device for metering by weight the delivery of liquids

A device for measuring the flow of liquids, particularly of fuels, comprising in combination a container for containing said liquid, an inlet and outlet aperture in said container, an undeformable measuring body of thermally stable material partly immersed in said container, an electrically controlled valve controlling the delivery of said liquid into the container through said inlet aperture, spring means fastened to said container and to said measuring body to deflect proportionally to the level of the liquid in the container, a transducer, coupled to the spring means and to said container, an electrical generator driving said transducer, first, second and third comparators each having a non-inverting input, and an inverting input and an output, said non-inverting inputs being connected to said transducer, three reference sources connected to said inverting inputs respectively, a first flip-flop having a first input j connected to the output of said first comparator, a second input k connected to said third comparator and an output, a second flip-flop having a first input j connected to the output of said second comparator, a second input k and an output q, amplifier means having an input connected to said output q of said first flip-flop and an output operatively connected to said electrically controlled valve to operate said valve to maintain liquid in said container between maximum and minimum levels, a timer having input connected to the output of said second flip-flop and an output connected to the second input k of said second flip-flop, a digital voltmeter connected to said transducer and to the output q of said second flip-flop, and a control source controlling said first and second flip-flops through a control switch, whereby the switching of said second flip-flop releases said digital voltmeter to respond to the output of said transducer and actuates the timer which, after its timing period, inhibits the voltmeter from responding to said transducer so that the digital voltmeter reads a quantity representative of liquid delivery rate at the conclusion of said timing period.