Abstract: Individually actuatable digital valve elements in parallel interconnect a fluid source to a receiver. In the flow passage of each valve element, there is a converging-diverging nozzle that feeds into the receiver. A trim adjustment screw is movable along the axis of each nozzle to vary the effective cross-sectional area of such nozzle. The nozzle and screw are part of an insert that can be mounted in the valve body after individual calibration.

Abstract: A plurality of individually actuatable, value weighted digital bistable valve elements in parallel interconnect a fluid source to a fluid receiver. A linear relationship is preferably maintained between the resultant fluid flow rate from the source to the receiver and the product of a flow rate determinative fluid parameter times the sum of the weighted values of the digital valve elements in the open state. The fluid parameter is sensed, the states of the digital valve elements are controlled, and a flow rate representative signal is derived from the states of the valve elements and the fluid parameter. If the fluid is liquid, the parameter is the square root of the pressure difference across the valve elements, in the absence of cavitating venturis, and is the square root of the difference between the upstream pressure and the vapor pressure of the liquid in the presence of cavitating venturis. If the fluid is gas, the parameter is the source pressure divided by the square root of the source temperature.