The Foxboro Company

Avgi Engineering, Inc.

Waters Investments Limited

Millipore Corporation

George E Sgourakes

Stanislaw Koziol

John P Angelosanto

Richard W Kalinoski

David A Richardson

Duane T Thompson

Carlton H Paul

John L Koukol, Jr

John R Curran

Richard L Vigeant

Robert C McCullough

Paul J Lefebvre

Barry T Malloy

Joseph F Actor

Mark D Freeman

Methods of compensating for undesired influences in a pressure transmitter wherein the pressure transmitter comprises a body for housing a low-pressure sensor and a high-pressure sensor each of which is in fluid communication with a port and in further fluid communication with each other through a connector tube containing a fill fluid. Various embodiments of the compensation process use one of the high-pressure and the low-pressure sensor as a common reference, compensating for changes in calibration, such as changes in the effective areas or spring rates of the non-reference sensor.

Differential pressure transmitter with intrinsic verification

A differential pressure transmitter is disclosed, which comprises a body for housing a high-pressure sensor and a low-pressure sensor, a plurality of high-pressure process connectors formed in said body and fluidly coupled to said high-pressure sensor for transmitting a first pressure of a process fluid to said high-pressure sensor, each of said high-pressure process connectors comprising a conduit having an opening for receiving the process fluid, a plurality of low-pressure process connectors formed in said body and fluidly coupled to said low-pressure sensor for transmitting a second pressure of a process fluid to said low-pressure sensor, each of said low-pressure process connectors comprising a conduit having an opening for receiving the process fluid, wherein said second pressure is equal to or less than said first pressure, wherein said openings of the high-pressure connectors are spaced relative to said openings of the low-pressure connectors to allow a plurality of pair-wise connections to the process fluid.

The present invention provides a dual sensor differential pressure transmitter with a single fill fluid volume that intrinsically eliminates process and environmental performance influences, increases signal level while substantially reducing product costs.

A vortex flow meter that senses the alternating pressure variations generated by a fixed vortex shedding generator. The alternating pressure variations of the vortices within the rows on each side of the vortex shedding generator act upon flexible elements producing forces on long columns that are transmitted to remotely located piezoelectric force sensors. The alternating forces upon the two columns are used to determine the passage of a vortex and thereby the flow. Improved output signal by minimizing loss of parasitic energy. 97% of the available signal is applied to the piezoelectric force sensors as compared to conventional 60%. Process influences such as vibration in all planes and pumping pulsations are equal and opposing and are rejected by the sensor. A capability of operating at extreme process temperatures is assured for the high temperature of the process is dissipated to the environment along the long columns. Reliability of operation is assured for the sensor has no process seals and is easily replaced by technicians, without interrupting flow or venting process. Improved process containment is realized with construction having a high safety factor and multiple stages of process containment. Wafer form reduces installation costs and an optional redundant sensor improves reliability of operation, decreases pumping losses, and only requires one K-factor. Process up-time is assured with an economical redundant sensor.

Vortex flow meter

A fluid transfer device includes a cylinder and a displacement rod. The cylinder is fabricated rigid enough to minimize distortion of volume yet compliant enough to create a seal between itself and the surface of the displacement rod. The cylinder is constructed with a bore hole through its central portion running from end to end. The diameter of the bore hole is larger than the diameter of the displacement rod. The displacement rod is constructed of a rigid material. At least one end of the cylinder has a diameter reduced so the diameter of the bore hole and the diameter of the displacement rod are substantially the same to form a seal with each other. As the displacement rod is withdrawn from the bore hole, a sample is drawn into the bore hole. The volume of the sample drawn into the bore hole is a function of the volume of the displacement rod withdrawn from the bore hole. A cross hole, for venting undesired fluid such as gas bubbles or previous sample(s), is located on the displacement rod. The cross hole is connected to a passageway through the inside of the displacement rod leading to an opening on its surface which is outside of the cylinder.

Autosampler syringe with compression sealing

Differential pressure generator,includes a stacked pair of opposed novel gravity transducers of the inverted-cup falling-cylinder type. First enclosure,contains a first gravity transducer,and second enclosure,contains a second gravity transducer,. First gravity transducer,includes first cylinder,, and first piston,. The first cylinder is mounted for gravity-driven, viscosity-limited motion with respect to the first piston to generate a first pressure difference. The second gravity transducer includes a second cylinder and a second piston. The second cylinder is mounted for gravity-driven, viscosity-limited motion with respect to the second piston to generate a second pressure difference. The first cylinder has a displacement volume that is equal to the displacement volume of the second cylinder, and the first cylinder is heavier than the second cylinder. The first pressure difference and the second pressure difference are summed in opposition to produce a reference differential pressure.

Differential pressure generator

A magnetostrictive pump is provided which makes use of a magnetostrictive element which, when an alternating magnetic field is applied to it, compresses a chamber containing a working fluid. A bellows located within the working fluid is repeatedly compressed by the compression of the chamber, and pumps a fluid to be pumped in and out of the bellows. Since the magnetostrictive element does not directly contact the bellows, the bellows life is greatly extended. Valves are provided to direct the fluid flow in a desired manner. The pump may be combined with other pumps in various series or parallel arrangements to create a pump system. The pump may be pre-biased to make its response more linear by either mechanical or magnetic biasing. A permanent magnet may be used to magnetically bias the pump and create an 'at-rest' initial extension of the magnetostrictive element. Similarly, a spring may be used to mechanically load the magnetostrictive element. A controller is used to detect feedback signals from pressure and pump displacement transducers, and thereby provide active control of the pump or pump system. It is especially useful for high performance liquid chromatography.

Durable high-precision magnetostrictive pump

A sealing means is provided that may be used, among other things, for sample injection apparatus used in liquid chromatography. The seal includes a jacket having a central bore through which a hypodermic needle containing a sample is inserted. The jacket includes a U-shaped cross section having an inner axial surface and an outer axial surface. Metal cylindrical bands which function as springs are positioned tightly against the inner and outer axial surfaces respectively. Each band has a slot extending through its thickness and along its entire axial length.

Fluid seal

A differential pressure measuring system comprising a transmitter for a pressure-measuring instrument connected to a control room by a two-wire transmission line carrying a d-c signal powered from the control room and representing the measured pressure. The instrument includes a reference pressure device of the falling-ball type, wherein a ball is first lifted to an upper position and then allowed to descend under the force of gravity to produce a reference pressure pulse for calibrating the instrument span. The lifting device for the ball is a two-coil magnetic actuator powered by current from the two-wire transmission line, and is operable at a sufficiently low current to be classified intrinsically safe. The reference pressure device is supported by an adjustable mounting providing two degrees of freedom for movement so as to permit ready adjustment of the device orientation to assure alignment with the force of gravity.

System for calibrating the span of pressure measuring instruments

Floating the diaphragm portion of a diaphragm sensor in the pressurizing fluid frees the diaphragm from exterior housing forces, and makes overall manufacture and replacement inexpensive. A diaphragm can be protected from exterior stress by interspersing a channel between the diaphragm edge and the closure and support structure of an enclosing housing. By extending the channel and incorporating an adequate seal, the diaphragm structure may be made replaceable. The replaceable diaphragm further allows use of a smaller amount of costly materials, and makes repair less costly.

Floating diaphragm apparatus

A differential-pressure transmitter having a range diaphragm and a slack diaphragm to receive process pressures and to apply such pressures to an interior sealed chamber containing a fill-liquid. An internal passageway between the regions adjacent the diaphragms provides for transfer of fill-liquid in response to differential pressure changes. The passageway serially includes a vertically-oriented tube containing a ball of magnetic material and surrounded by a solenoid winding. Energization of the winding lifts the ball to the top of the tube. When the winding is de-energized, the ball drops down through the fill-liquid to create a reference pressure pluse which is directed to the range diaphragm to correspondingly alter the instrument output signal. The output signal is monitored to check the span calibration, and adjustments are made as needed.

Apparatus and method for calibrating span of pressure measuring

A differential-pressure transmitter having a range diaphragm and a slack diaphragm to receive process pressures and to apply such pressures to an interior sealed chamber containing a fill-liquid. An internal passageway between the regions adjacent the diaphragms provides for transfer of fill-liquid in response to differential pressure changes. The passageway serially includes a vertically-oriented tube containing a ball of magnetic material and surrounded by a solenoid winding. Energization of the winding lifts the ball to the top of the tube. When the winding is de-energized, the ball drops down through the fill-liquid to create a reference pressure pulse which is directed to the range diaphragm to correspondingly alter the instrument output signal. The output signal is monitored to check the span calibration, and adjustments are made as needed.

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Millis, MA, United States of America

George E Sgourakes