Patent ID: 7069137

Claim:
A gas control valve, comprising: a variable flow metering device capable of realizing a plurality of predetermined mass flow rates by varying configuration of the flow metering device; at least one sensor configured to: a. detect variable configurations of the flow metering device and generate a first output signal that is a function of the configuration of the flow metering device; b. detect fluid pressure upstream of the flow metering device and generate a second output signal that is a function of the detected upstream fluid pressure; c. detect fluid pressure downstream of the flow metering device and generate a third output signal that is a function of the detected downstream fluid pressure; d. detect temperature upstream of a flow metering device and generate a fourth output signal that is a function of the detected temperature; memory including first computer program code for calculating a combined coefficient of discharge times area that gives a desired flow for a given configuration of the flow metering device, upstream pressure, downstream pressure, and temperature for subsonic flow and second computer program code for calculating a combined coefficient of discharge times area that gives a desired flow for a given configuration of the flow metering device, upstream pressure, and temperature for sonic flow; and processing circuitry configured to receive the signals, determine whether flow is subsonic or sonic, and implement a corresponding one of the first and second computer program codes to calculate a combined coefficient of discharge times area that will generate a desired mass flow rate for the flow metering device.