Abstract: A device for metering and controlling fluid flow includes a variable orifice and is configured to use a pressure sensor. The device includes a fluid flow conduit having at least one planar inner wall that extends along a portion of the fluid flow conduit length, and an element having a linear edge configured to mate with the at least one planar inner wall of the fluid flow conduit. The element is movable in a direction transverse to an axis of the conduit between an open position wherein fluid flows through the conduit and a closed position wherein the element substantially shuts off fluid flow in the conduit.

Abstract: A device for metering fluid flow is disclosed. The device includes a variable sized orifice defined by a fluid flow conduit and an element movable relative to the fluid flow conduit to vary a size of the orifice, a pressure sensor configured to determine a pressure differential across the orifice and generate a pressure signal, a positioning device configured to determine a position of the element relative to the conduit and generate a position signal, and a processor configured to determine the fluid flow rate using the pressure signal and the position signal. The system can directly control the adjustable valve or orifice. Alternatively, the system can move back and forth between a direct mode and a PID mode. When in a PID mode, the system employs a standard PID algorithm with a variable gain term. The system switches to direct mode when it is advantageous for the controller to directly change the valve position based upon the setpoint, and the input and output pressures.

Abstract: A method of improving the accuracy of a variable orifice flow meter that includes characterizing the flow coefficient of the flow meter orifice for different orifice openings and for different differential pressures. The method may be particularly useful with a flow metering and controlling device that includes a fluid flow conduit having at least one planar inner wall and an element having a linear edge configured to mate with the at least one planar inner wall of the fluid flow conduit. The element is movable relative to the conduit to define a flow orifice and vary a cross-sectional area of the orifice. The device also includes a processor configured to calculate the fluid flow based on the cross-sectional area of the orifice, the differential pressure, and the flow coefficient.

Abstract: A method of improving the accuracy of a variable orifice flow meter that includes characterizing the discharge coefficient of the flow meter orifice for different orifice openings and for different differential pressures. The method may be particularly useful with a flow metering and controlling device that includes a fluid flow conduit having at least one planar inner wall and an element having a linear edge configured to mate with the at least one planar inner wall of the fluid flow conduit. The element is movable relative to the conduit to define a flow orifice and vary a cross-sectional area of the orifice. The device also includes a processor configured to calculate the fluid flow based on the cross-sectional area of the orifice, the differential pressure, and the discharge coefficient.

Abstract: A method of improving the accuracy of a variable orifice flow meter that includes characterizing the flow coefficient of the flow meter orifice for different orifice openings and for different differential pressures. The method may be particularly useful with a flow metering and controlling device that includes a fluid flow conduit having at least one planar inner wall and an element having a linear edge configured to mate with the at least one planar inner wall of the fluid flow conduit. The element is movable relative to the conduit to define a flow orifice and vary a cross-sectional area of the orifice. The device also includes a processor configured to calculate the fluid flow based on the cross-sectional area of the orifice, the differential pressure, and the flow coefficient.

Abstract: A device for metering and controlling fluid flow includes a variable orifice and is configured to use a pressure sensor. The device includes a fluid flow conduit having at least one planar inner wall that extends along a portion of the fluid flow conduit length, and an element having a linear edge configured to mate with the at least one planar inner wall of the fluid flow conduit. The element is movable in a direction transverse to an axis of the conduit between an open position wherein fluid flows through the conduit and a closed position wherein the element substantially shuts off fluid flow in the conduit.