Abstract: A system and method for controlling at least one hydraulic actuator of a hydraulic system includes a flow rate measurement of a hydraulic fluid flow traveling into and out of a cavity of the hydraulic actuator. The flow rate is used to calculate piston information corresponding to a position, velocity, acceleration, and/or direction of movement of a piston of the hydraulic actuator. The piston information can then be provided to an output device to aid in the control of the hydraulic actuator. Alternatively, the piston information can be compared to a reference signal relating to a desired position, velocity, acceleration, and/or direction of movement of the piston to produce a control signal, which can be used to adjust the hydraulic fluid flow and provide the desired actuation of the piston.

Abstract: A pressure transmitter produces signals indicative of a flow in a pipe. The transmitter has a pressure sensor that is fluidly coupled to two ports in the pipe, and the pipe has a substantially constant cross-section between the two ports. Aspects of the invention include a circuit coupled to the pressure sensor that produces a digital value related to the fluid flow as a function of the pressure difference between the two ports.

Abstract: A transmitter provides an output signal indicative of mass flow rate of fluid through a conduit. The transmitter includes a temperature sensor providing a temperature signal indicative of fluid temperature. A static pressure sensor provides a static pressure signal indicative of static pressure in the conduit. A differential producer provides a differential pressure signal. The transmitter also includes a controller which provides the output signal indicative of mass flow of the fluid through the conduit.

Abstract: A vortex sensor senses the generated vortices and provides a vortex signal. A filtering circuit is coupling to the vortex sensor to receive the vortex signal and provide an output indicative of fluid flow. A temperature sensor senses a temperature of the fluid and provides a temperature value, while a pressure sensor senses a pressure of the fluid and provides a pressure value. A processor is operably coupled to the filtering circuit, the temperature sensor, and the pressure sensor for receiving the output, the temperature value, and the pressure value, respectively. The processor calculates a calibration factor as a function of the output, the temperature value, and the pressure value for use in calculating the output value indicative of the flow rate of the fluid.

Abstract: A method in a pressure transmitter and a pressure transmitter for determining a mass flow rate of a fluid in a conduit measure a differential pressure between two points in the fluid, where the conduit has a substantially constant cross-sectional area between the two points. In one aspect, the mass flow rate is calculated by multiplying the square-root of the differential pressure by a mass flow constant.

Abstract: A two-wire transmitter senses differential pressure, absolute pressure, and process temperature of a process fluid. The information can be used to provide an output representative of mass flow through a pipe. The transmitter has an electronics module housing attached to a sensor module housing. The sensor module housing contains all the sensors for the pressures and includes a boss input for receiving a signal representative of a temperature or pressure signal. The three process variables are appropriately digitized, and received by an electronics circuit board in the electronics housing including a microprocessor for calculating the mass flow. The microprocessor in the electronics housing also calculates a compressibility factor and a discharge coefficients according to a polynomials of specific forms. The boss is integral to the sensor module housing and is adapted to fit either shielded twisted pair cabling or conduit.

Abstract: A transmitter in a process control system for measuring flow rate measures total pressure (P.sub.TOT) and differential pressure (h) of process fluid flowing through a process pipe. The static pressure (P.sub.STAT) is determined based upon the total pressure (P.sub.TOT). The calculated static pressure is used to determine the fluid density (.rho.) and the gas expansion factor (Y.sub.1) of the process fluid flowing in the pipe. This information is used to calculate flow rate (Q) of the process fluid.

Abstract: A two-wire transmitter senses a pressure using an internal pressure sensor. The transmitter includes an input for receiving a process variable from a remote sensor which is separated from the transmitter. Circuitry in the transmitters transmits information on a two-wire process control loop which is related to the sensed pressure and the process variable.

Abstract: A piezoelectric fluid pressure fluctuation frequency sensor, preferably for a vortex-shedding flowmeter. A piezoelectric transducer is located in a sensor chamber between and in physical contact with a diaphragm and a chamber surface. Pressure fluctuations in a von Karman vortex street outside the diaphragm compress the transducer, between the diaphragm and the chamber surface. The transducer generates a responsive electrical signal which is representative of the pressure fluctuations.

Abstract: An improved flow meter and sensor body therefor, the body having a strain relief portion. A housing of the flow meter defines a fluid flow passage and a sensor body opening. A sensor body mounting portion is mounted to the housing. A sensor body sensor supporting portion is in the fluid flow passage, and supports flow sensor transducers in the fluid flow. The sensor body relief portion is intermediate the sensor body mounting and supporting portions, in the sensor body opening, and adapted to relieve induced strain from external vibration, whereby the flow meter is substantially insensitive to external vibration.

Abstract: A pneumatic process controller includes a nozzle mounted on a set point lever and a flapper with a connected process lever. The set point lever pivots the nozzle about a set point and input axis in response to set point adjustment. The process lever pivots the flapper about the same axis in response to the process variable. The nozzle and set point lever are mechanically separated from the flapper and process lever. Artificial effect upon the process variable from set point adjustment is eliminated.

Abstract: A vortex-shedding flowmeter comprising two stationary vortex-shedding cross-members (i.e., bluff bodies) disposed transversely to a stream of fluid. Each cross-member has a bluff face with sharp Karman vortex generating edges with independently selected edge to edge widths d of from 10 to 40% of the inside width of the conduit through which the fluid flows and lengths 1 of from 0.3 to 2.0d. The second cross-member is disposed downstream of the first cross-member a distance of from 4 to 15 times the width d of the first cross-member. Any sensor may be used in any location provided it or they sense the Karman vortices generated by co-action of the two cross-members. This flowmeter provides strong signals with a high signal to noise ratio and high Strouhal number.