Patent ID: 6119528
Filing Date: 2000-09-19
Classification: G01F

Abstract:
A system for measuring liquid flow, comprising:a flow meter for indicating a flow rate of a fluid flowing therethrough; the flow meter having a housing composed of a generally cylindrical tube, the generally cylindrical tube having an inlet, an outlet, and a passageway extending between said inlet and outlet, a flow sensing member mounted within the passageway, and a signaling element mounted on the housing to provide a signal corresponding to the flow rate of the fluid;a signal-conditioning circuit connected to the signing element to receive said signal from the signaling element, and to convert said signal into a 4-20 mA output signal indicative of the flow rate of the fluid through the passageway;a flow totalizer connected to the signal-conditioning circuit and responsive to the output signal from the signal-conditioning circuit the flow totalizer processing the 4-20 mA output signal to an accumulated total of the fluid flowing through the passageway; andan ultrasonic fluid sensor having a first end and a second end, said sensor mounted through the housing with the second end disposed within the passageway and the first end connected to the signal-conditioning circuit; the second end of the ultrasonic fluid sensor sensing the liquid in the passageway and interrupting transmission of the 4-20 mA output signal from the signal-conditioning circuit to the totalizer when there is substantially no liquid present in the passageway.