Abstract: A sensor assembly for a fluid flow meter, more particularly a gas meter, includes a sensor well made of a non-magnetic material and a sensor which is removable from the well without depressurizing the fluid line in which the flow meter is located. The sensor well is mounted within a bore formed in a meter body boss and, in a preferred embodiment, extends through the internal rotor housing and includes an inner face contoured to conform to the inner wall of the housing. In certain embodiments of the invention, the sensor is shaped to cover the sensor well mounting bolts so that the well cannot be removed without first removing the sensor. In other embodiments, the sensor well mounting bolts are retained in the sensor well by dowel pins, stakes or retaining rings such that the bolts must be gradually and sequentially loosened to remove the sensor well, in order to prevent improper removal of the sensor well from the meter body boss.

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 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: The flow tube of a ceramic material used for a magnetic flowmeter is formed with electrodes that are positioned in the wall of the tube and form a fluid tight fitting. The electrodes have a center plug made of a ceramic material with a metallization layer between the plug and the surface of the opening in the flow tube. The inner ends of the plugs are covered with a conductive ceramic electrode layer that electrically joins the metallization on the plugs to couple the EMF generated by the flowing fluid to the exterior of the flow tube. The conductive ceramic layer is engaged by the fluid in the flowmeter to protect the metallization from erosion. The electrodes are connected to suitable circuitry on their exterior ends.

Abstract: A vortex sensor used in a vortex flowmeter that has a single sensing diaphragm parallel to the direction of flow that is sensitive to differential pressures caused by vortices shed by a vortex shedding bar associated with the sensing diaphragm. A beam is attached to the sensing diaphragm and it transfers the deflecting motion of the sensing diaphragm due to differential pressures to a sensor external to the flow passageway. The sensor provides an output indicating motions of the beam caused by the beam pivoting when the sensing diaphragm deflects. The beam preferably is pivoted on a relatively rigid, fluid-tight isolator diaphragm with one end of the beam on the outside of the isolator diaphragm. The sensing diaphragm which is used to measure differential pressure rejects variations in the static pressure, that is, increases and decreases of the static pressure on both sides of the diaphragm, which is a common source of problems with existing vortex flowmeter sensors.

Abstract: The optical displacement sensor modulates intensity of the light beam as a function of the physical displacement. The sensor includes a reflector positioned in a path of the light beam between a light source and a light detector. The reflector has a non-reflective portion surrounded by a reflective portion. Relative movement (displacement) of the beam and the reflector occurs as a function of a parameter which is being sensed. In a normal (no displacement) condition, the non-reflective portion can be positioned with respect to the light beam so that intensity of the light beam received by the detector is at a minimum, and the sensor is operating in a darkfield mode. Displacement from the normal position causes an increase in the light intensity received by the detector.

Abstract: A differential pressure sensor (10) adapted specifically for use with vortex shedding flowmeters which can be used in small spaces, uses a bending beam (60) for providing an electrical signal proportional to differential pressures between two oppositely facing diaphragms (40A, 40B). The diaphragms deflect under differential pressure and cause the beam (60) to be bent. The diaphragms have low mass and have a support structure (43) between them, carrying spring clips (50) which load one end of the bending beam (60). The other end of the bending beam (60) is then supported so it cantilevers from its mounting or support (61, 62) and upon movement of the diaphragms under differential pressure the beam (60) will bend. The signal can be derived by using a bending element made of a piezoelectric "bimorph" beam, which provides a voltage output as it bends, a strain gauge sensor on a beam, or an optical sensor, such as a fine fiber which deflects and provides an optical output may be used, as well as similar devices.

Abstract: A vortex flowmeter utilizes a bluff body which has three sections: An upstream head member, an intermediate section co-extensive with the head member, having a width less than that of the head member, and a tail section having a width greater than the intermediate section but less than the head section. A differential pressure sensor is mounted in the intermediate section. For different pipe sizes the head member and tail section are varied but the intermediate section width is maintained constant. This allows interchangeability of the pressure sensor in the intermediate section.