Abstract: Disclosed is a bi-directional differential pressure flow sensor that is configured to establish a direction and flow rate of a fluid flow. The flow sensor includes a flow restriction member, a differential pressure sensor, and processing electronics. The flow restriction member is configured to produce a pressure drop when placed inline with the fluid flow. The differential pressure sensor is embedded or integral with the flow restriction member and produces a differential pressure signal that is indicative of the pressure drop. The processing electronics produces a flow rate signal that is indicative of the direction and flow rate of the fluid flow as a function of the differential pressure signal.

Abstract: A device measures air flow at multiple points in an air channel. The device includes a metering plate that has multiple passages through the metering plate. The metering plate is adapted to be positioned across the air channel in an orientation that places two or more of the multiple passages at two or more respective locations within the air channel. The metering plate is also adapted to receive two or more flow meters at the two or more passages, respectively. In addition, the metering plate is configured so that respective air flow velocities at the two or more locations when the metering plate is positioned across the air channel substantially matches air flow velocities at the two or more locations when the metering plate is not positioned across the air channel. An example embodiment includes holders such as sockets that keep the flow meters fixed in the metering plate with regard to pitch and roll.

Abstract: There is provided a multi-stage variable orifice flow obstruction sensor for measuring a fluid flow. The sensor comprises a body member having an aperture therethrough. Moreover, a cover member is engaged to the body member and is disposed within the aperture. The cover member is adapted to transition between open and closed positions with respect to the aperture. Additionally, a flow-limiting obstruction member is engaged to the body member and is disposed within the aperture adjacent the cover member. The flow-limiting member is configured to apply a generally opposing force to the cover member when the cover member extends to the open position and contacts the flow-limiting member. By doing so, a pressure differential of the fluid may be sensed such that the fluid flow can be measured therefrom.

Abstract: Improvement in a mass air flow meter having an elongated hollow body having a venturi member therein, the improvement comprising channels formed in the outside surface of the venturi member, lands defined by such outside surface which bear against the inside surface of the hollow body, such lands, together with the inside surface of the hollow body, directing the flow of sample air to be measured through such channels, around the outside surface of the venturi member and axially thereof, a first one of the channels being annular and in communication with the interior of the meter for receiving sample air therein, a second one of the channels serving as a measurement path in which the mass of sample air is measured as it travels therethrough, and a third one of the channels being annular and in which air exiting from the measurement path is accumulated before being recombined with the main flow of air traveling through the meter.

Abstract: Devices for determining at least one parameter of a flowing medium having an inner pipe according to the related art have the disadvantage that whirls are formed, which causes increased signal noise at the measuring element and pressure drop.

Abstract: Method and device for monitoring the flow speed of an infusion solution, such as with hemofiltration or hemodiafiltration. The device has a tube for conducting an infusion solution from a source of infusion solution to a pump device in the form of a metering pump, such as a peristaltic pump or a ceramic pump, and on to an infusion device, such as a drip chamber. The flow speed is determined by the metering pump. The flow speed is monitored separately in that the pressure across a restriction device in the tube is measured. The restriction device can be a separately arranged restriction valve. Alternatively the restriction device is arranged by the tube having a small internal diameter of the order of 0.5 mm in size. The pressure measuring device only needs to measure the absolute pressure with respect to the atmosphere. The hydrostatic pressure due to the infusion bag being hung above the pump and the pressure meter is subtracted in a calculation device.

Abstract: An apparatus for monitoring fluid flow within a high pressure liquid chromatography system. The apparatus includes a pump for supplying a system flow of eluent to the system, a chromatography column, a flow splitting device having a first restrictor fluidly connecting the pump and the chromatography column, a second restrictor fluidly connecting the pump to a waste line, a first fluid pressure sensor monitoring a system fluid pressure upstream of the first restrictor, and a second fluid pressure sensor monitoring a column fluid pressure downstream of the first restrictor. A method of using the apparatus for fluid flow control is also disclosed.

Abstract: A method and apparatus for determining a state of zero gas flow in a conduit. A first gas flow signal has one polarity when gas flow is in one direction in the conduit and the opposite polarity when gas flow is in the opposite direction. A second gas flow signal has the same polarity for either direction of gas flow in the conduit. The derivatives of the first and second signals are taken at successive points in time to determine when the signs of the derivatives are present in a first predetermined combination of signs. A second point in time when the signs of the derivatives exhibit a second predetermined combination of signs different from the first combination is also determined. The combinations of signs are used to identify a state of zero gas flow in the conduit.

Abstract: A flow meter for measuring the volume of fluid flowing through the meter includes an inner cylindrical tube through which the fluid flows and an outer cylindrical tube tending over the inner cylindrical tube. The outer cylindrical tube is radially spaced from the cylindrical inner tube to provide an annular cylindrical space between the inner cylindrical tube and the outer cylindrical tube. A seal between said inner cylindrical tube and the outer cylindrical tube closes the annular cylindrical space adjacent ends of the annular cylindrical space. The inner cylindrical tube further defines at least one opening in a wall of the inner cylindrical tube to balance the fluid pressure in the annular cylindrical space with the pressure in the inner cylindrical tube. A flow restriction member is mounted to an inner surface of said inner cylindrical tube for restricting the flow of fluid through the inner cylindrical tube and produces a pressure drop in the fluid as it flows past the flow restriction member.

Abstract: A fluid delivery system having a closed-loop control process for delivering a medical fluid to a patient. A fluid infusion system includes a pump for delivering a fluid to a patient via an administration tube. A flow sensor associated with the administration tube provides an indication of the actual flow rate of fluid in the administration tube. Such a flow sensor may comprise a positive displacement flow sensor constructed using micro-fabrication and/or micro-molding techniques. A reader reads the actual flow rate signal and provides an indication to a controller for controlling the pump. The flow rate information can also be used for providing status information, such as the existence of a blockage in the fluid delivery system.

Abstract: A flow meter for measuring the volume of fluid flowing through the meter includes an inner cylindrical tube through which the fluid flows and an outer cylindrical tube tending over the inner cylindrical tube. The outer cylindrical tube is radially spaced from the cylindrical inner tube to provide an annular cylindrical space between the inner cylindrical tube and the outer cylindrical tube. A seal between said inner cylindrical tube and the outer cylindrical tube closes the annular cylindrical space adjacent ends of the annular cylindrical space. The inner cylindrical tube further defines at least one opening in a wall of the inner cylindrical tube to balance the fluid pressure in the annular cylindrical space with the pressure in the inner cylindrical tube. A flow restriction member is mounted to an inner surface of said inner cylindrical tube for restricting the flow of fluid through the inner cylindrical tube and produces a pressure drop in the fluid as it flows past the flow restriction member.

Abstract: An integrated module is provided for measuring a flow rate of a fluid, whether gaseous or liquid, with a flow restrictor comprising a plurality of orifices adapted to a flow channel of the integrated module and a sensor mounted to measure a property of the fluid at said flow restrictor corresponding to the flow rate. The integrated module provided may be used in numerous flow systems, such as reactors, ventilators and respirators, and has the benefit of better laminarization of the flow as well as better calibration between the flow sensor and the flow restrictor for more accurate flow measurements.

Abstract: A measurement system is described that includes a flow conditioner for performing the dual functions of conditioning the flow stream and acting as a check meter to the primary meter. Various flow stream characteristics are calculated from the measured differential pressure across the flow conditioner. These calculated values are compared to measurements made by the primary meter for the purpose of identifying performance or accuracy problems in the measurement equipment.

Abstract: A novel flow sensor that includes a valve responsive to a pressure differential or pressure drop across a selectively sized restriction orifice. The flow sensor may be incorporated into a high-pressure fuel injection system for sensing the opening and closing of high pressure fuel injector for injecting gaseous fuel.

Abstract: A flow adapter for measuring the rate at which air flows into the brake pipe. The adapter includes a housing, a flow valve and a transducer. The primary passage of the housing contains a primary orifice and a secondary passage contains a secondary orifice. The flow valve is disposed within a supplemental passage. When the rate of air flowing from the input passage into the input chamber is less than or equal to a predetermined amount, the flow valve closes the supplemental passage. When the flow rate into the input chamber is greater than the predetermined amount, the flow valve opens the passage to an extent determined by the magnitude of the flow rate. This allows air to flow through the supplemental passage, in addition to that flowing through the primary passage. The transducer generates a signal proportional to the difference in pressure between input and output chambers.

Abstract: A separator partitions an upstream side air passage of a bypass passage into first and second sub passages. A thermal flow sensor is attached to the separator facing the first sub passage. A convex is formed on the inner wall of an outer pipe defining the second sub passage. The convex protrudes toward the separator. Minimum flow passage area S2 of the second sub passage is smaller than minimum flow passage area S1 of the first sub passage, so that flow passage loss of the second sub passage is larger than flow passage loss of the first sub passage. Thus, measured air-flow amount average when the air-flow pulsates is corrected to be larger.

Abstract: A flow sensor for an analytical instrument. The flow sensor can be used to detect the flow of a fluid such as purge gas in the instrument. The sensor can measure the fluid flow at an opening of the instrument enclosure. The sensor has first and second differential pressure switches connected in series. The sensor has a sealed chamber which is in the opening. Bordering the sealed chamber are first and second restrictors through which the fluid can flow. A sensing tube transfers the pressure in the sealed chamber to the first and second switches.

Abstract: A differential pressure flow rate measurement apparatus comprises:

Abstract: A flow meter and method for determining the corrected flow rate of a liquid falling into a predetermined class of liquids based on its viscosity and density is disclosed. The flow meter comprises a flow sensor for measuring an uncorrected flow rate of the liquid, a temperature sensor for measuring the temperature of the liquid, and a microprocessor for calculating the corrected flow rate based on the liquids predetermined class and the measured temperature. The flow sensor can include a restriction in the fluid flow path, first and second pressure sensors positioned one on each side of the restriction and a temperature sensor. The first and second pressure sensors measure the drop in fluid pressure created by the restriction and the temperature sensor measures the temperature of the liquid. By basing the corrected flow rate calculation on the predetermined class of the liquid, the calculation becomes a closed form solution that is deterministic providing for quick and accurate corrected flow rate calculation.

Abstract: A fan powered by a controlled external energy source and a flow measurement device measure the airflow exiting or entering grilles/registers of an HVAC system without impeding the airflow being measured. A flow straightening element is preferably employed to overcome any effects of a non-uniform or swirled airflow profile on the fan. Preferably, the RPM of the fan is measured to determine the airflow. The RPM/flow calibration of the fan is insensitive to pressure differentials or the fan is a pressure-sensitive fan submitted to appropriate pressure differentials. Alternatively, the voltage or current supplied to the external energy source is used to determine the airflow. Finally, the pressure differential across the flow straightening element can be measured to determine airflow, eliminating the impact of pressure differential across the flow measurement device and fan.

Abstract: A flowmeter based on the pressure difference across a flow resistance element which is an array of surfaces generally parallel to the flow direction, which is operated such that over at least part of its range the Reynolds number is larger than the traditional limiting Reynolds number for laminar flow of approximately 2000. Also, the L/D ratio is shorter than in a traditional laminar flow element, so that for at least part of its range its operation is determined by the behavior of boundary layers forming on those surfaces. Such a flow resistance element provides a pressure drop vs. flowrate relationship which over a wide range of flow conditions is less steep than quadratic. This allows a larger flowrate turndown ratio for a given range of differential pressure measurement. The flowmeter may additionally comprise other sensors and a microprocessor.

Abstract: A disposable differential pressure pneumotachometer includes an inlet chamber having an air inlet, an outlet chamber having an air outlet, and a resistive element disposed between the inlet and outlet chambers. Air flow across the resistive element results in a pressure gradient which is measured to provide air flow rate. According to one aspect of the invention, the pressure port through which the static pressure in the inlet chamber is sensed is disposed in the outlet chamber. According to a further aspect of the invention, the resistive element comprises a bacterial filter material. Also described is a pneumotachometer in which at least one pressure port is covered with a bacterial filter material.

Abstract: A fluid control module that may be connected in-line within a chemically corrosive or ultra pure fluid flow circuit that delivers fluids in either a liquid or gaseous state. The fluid control module of the present invention may be utilized to control the flow, pressure or volume of fluid flowing through the fluid flow circuit and is capable of automatically adjusting or “calibrating” the module to compensate for changes in atmospheric pressure or drift in the pressure sensors of the fluid control module. The fluid control module also includes a rapid or macro adjustment of the control valve to reach the desired flow rate at a quicker pace.

Abstract: A method and device for use with a hydraulic system is adapted to measure a position, velocity and/or acceleration of a piston of a hydraulic actuator based upon differential pressure measurement. The device of the present invention utilizes a differential pressure flow sensor to establish a flow rate of a hydraulic fluid flow traveling into and out of a cavity of the hydraulic actuator, from which the position, velocity and acceleration of the piston can be determined.

Abstract: A disk probe velocimeter is formed by multiple orthogonal disks fitted with pressure transducers positioned to measure dynamic pressure differences between the center of one disk face and the center of the other face of each disk. The velocimeter can measure reasonably accurately three components of velocity where the approximate direction of the flow is not known. Where the dominant velocity component is known, the velocimeter may be combined with a Pitot probe to form a compact anemometer.

Abstract: There is provided a multi-stage variable orifice flow obstruction sensor for measuring a fluid flow. The sensor comprises a body member having an aperture therethrough. Moreover, a cover member is engaged to the body member and is disposed within the aperture. The cover member is adapted to transition between open and closed positions with respect to the aperture. Additionally, a flow-limiting obstruction member is engaged to the body member and is disposed within the aperture adjacent the cover member. The flow-limiting member is configured to apply a generally opposing force to the cover member when the cover member extends to the open position and contacts the flow-limiting member. By doing so, a pressure differential of the fluid may be sensed such that the fluid flow can be measured therefrom.

Abstract: A measurement system is described that includes a flow conditioner for performing the dual functions of conditioning the flow stream and acting as a check meter to the primary meter. Various flow stream characteristics are calculated from the measured differential pressure across the flow conditioner. These calculated values are compared to measurements made by the primary meter for the purpose of identifying performance or accuracy problems in the measurement equipment.

Abstract: A flow meter system that calculates mass flow rate based only on a single pressure signal. A flow controller is arranged in parallel with a restriction such that a constant pressure differential is maintained across the restriction. The pressure, and temperature if not controlled, of the fluid flowing through the restriction is measured on either side of the restriction. The pressure is compared to a plot of pressure versus mass flow rate calculated for the specific restriction and fluid being measured. The constant pressure differential maintained across the restriction yields a linear relationship between pressure and flow rate. If temperature is not controlled, the plot of pressure versus mass flow rate will remain linear, but the slope of the curve will be adjusted based on the temperature of the fluid.

Abstract: A flow meter system that calculates mass flow rate based only on a single pressure signal. A flow controller is arranged in parallel with a restriction such that it constant pressure differential is maintained across the restriction. The pressure, and temperature if not controlled, of the fluid flowing through the restriction is measured on either side of the restriction. The pressure is compared to a plot of pressure versus mass flow rate calculated for the specific restriction and fluid being measured. The constant pressure differential maintained across the restriction yields a linear relationship between pressure and flow rate. If temperature is not controlled, the plot or pressure versus mass flow rate will remain linear, but the slope of the curve will be adjusted based on the temperature of the fluid.

Abstract: A flow meter for use in an oil well has a central bore region in which an annular tube is fixed co-axially with the central bore region by a ring, which also seals the gap between the inner bore of the central bore region and the tube at its downstream end, thus forming a pocket open to the direction of fluid flow through the central bore region. The pocket brings the fluid to rest, thereby converting all of the dynamic pressure of the fluid into static pressure. This has the effect of maximizing the pressure differential obtainable between the central bore region and a position upstream of the tube, which allows an electronic calculation to be made to provide a more accurate flow rate measurement than would have been possible without the pocket.

Abstract: A dynamic flow adapter to be used in measuring the rate at which air flows into the brake pipe of a locomotive. The flow adapter includes a housing, a dynamic flow valve and a differential transducer. The housing defines an input passage, an input chamber, a primary passage, a supplemental passage, an output chamber, a secondary passage and an output passage. The primary passage contains a primary orifice having a first diameter. The secondary passage contains a secondary orifice having a second diameter. The input passage communicates with the input chamber, and the input and output chambers communicate through the primary orifice. The output chamber communicates with the output passage through the secondary orifice. The supplemental passage is in parallel with the primary passage and when opened allows further communication between the input and output chambers. The dynamic flow valve is disposed within the supplemental passage.

Abstract: A differential flow plate insertable into a flow path including a flow interrupter extending about an outer periphery of the flow path forming a constricted flow opening and a temperature sensor channel disposed proximate to the flow interrupter.

Abstract: A fluid control module that may be connected in-line within a chemically corrosive or ultra pure fluid flow circuit that delivers fluids in either a liquid or gaseous state. The fluid control module of the present invention may be utilized to control the flow, pressure or volume of fluid flowing through the fluid flow circuit and is capable of automatically adjusting or “calibrating” the module to compensate for changes in atmospheric pressure or drift in the pressure sensors of the fluid control module. The fluid control module also includes a rapid or macro adjustment of the control valve to reach the desired flow rate at a quicker pace.

Abstract: A fluid mass flow controller, particularly adapted for controlling mass flow rates of toxic and reactive gases used in semiconductor device fabrication, includes a control circuit connected to pressure sensors for sensing the differential pressure across a flow restrictor in the mass flow controller for controlling a valve to control the fluid mass flow rate to a setpoint. The control circuit compares the differential pressure with the downstream pressure at a measured temperature with a data set of a gas passing through the flow controller for a range of differential pressures and downstream pressures and adjusts the flow control rate accordingly. The flow controller is mechanically uncomplicated including a two part body for supporting the pressure sensors, a remotely controllable flow control valve and the flow restrictor.

Abstract: A device measures air flow at multiple points in an air channel. The device includes a metering plate that has multiple passages through the metering plate. The metering plate is adapted to be positioned across the air channel in an orientation that places two or more of the multiple passages at two or more respective locations within the air channel. The metering plate is also adapted to receive two or more flow meters at the two or more passages, respectively. In addition, the metering plate is configured so that respective air flow velocities at the two or more locations when the metering plate is positioned across the air channel substantially matches air flow velocities at the two or more locations when the metering plate is not positioned across the air channel. An example embodiment includes holders such as sockets that keep the flow meters fixed in the metering plate with regard to pitch and roll.

Abstract: A method for approximating compressible flow is described that is applicable across any pressure range of interest uses upstream and downstream pressure. The approximation minimizes variance with respect to a true flow equation. A flow control system is given using the new method that achieves accurate control with minimum complexities. The control system is application to various systems, including internal combustion engine airflow control, internal combustion engine exhaust gas recirculation control, internal combustion engine alternative fuel flow control, and many other compressible flow control problems.

Abstract: The invention comprises an improvement to the prior art differential pressure fluid flow meter described in U.S. Pat. No. 6,308,581. The prior art fluid flow meter includes a longitudinal recess angled to the surface of the vessel so as to form a ramp, and a dynamic port surface angled extending from the floor of the ramp to the surface. The dynamic port is formed in the dynamic port surface and is connected through a dynamic port channel to a pressure transponder. The improvement comprises combining the above described differential pressure fluid flow meter with a low pressure port, at an angle less than 90 degrees to the dynamic port, wherein fluid flow draws pressure from the low pressure port in a direction counter to fluid flow entering the dynamic port.

Abstract: A reactor pressure vessel (RPV) for a nuclear reactor that permits measurement of the flow through each reactor internal pump (RIP) is described. The reactor pressure vessel also includes at least one reactor internal pump that includes an impeller and a pump diffuser. At least two seal rings extend circumferentially around an outer surface of the diffuser housing outer wall and are located in circumferential grooves in the housing outer wall. At least one lateral bore extends through the housing outer wall into a diffuser housing longitudinal flow passage. Each lateral bore is located in an area between two adjacent seal rings, with each inter-seal ring area containing one lateral bore. At least one pressure tap bore extends from the outer surface of the RPV bottom head petal, through the pump deck to an inner surface of a pump deck opening. Each pressure tap bore is aligned with an area in the RIP containing a corresponding lateral bore.

Abstract: Improvement in a mass air flow meter having a static pressure manifold disposed upstream from an air flow path for sample air and capable of accumulating a volume of air therein, the flow path constructed to receive an air flow transducer, the static pressure manifold having an inlet arrangement in communication with the kinematic main air flow traveling through the meter so as to be capable of sensing different static pressures thereof, the static pressure manifold having a single outlet serving as the sole inlet for the sample air to be measured by the air flow transducer, the static pressure of the air accumulated in the static pressure manifold being such that it functions as a resultant average of the different static pressures sensed at its inlet arrangement, the static pressure manifold providing substantial immunity for the meter in respect to turbulent air flow upstream therefrom.

Abstract: A flowmeter for accurately measuring the flowrate of fluids in high pressure chromatography systems. The flowmeter is a porous bed of a material, the porous bed having a porosity in the range of about 0.1 to 0.6 and a pore size in the range of about 50 nm to 1 &mgr;m, disposed between a high pressure pumping means and a chromatography column. The flowmeter is provided with pressure measuring means at both the inlet and outlet of the porous bed for measuring the pressure drop through the porous bed. This flowmeter system provides not only the ability to measure accurately flowrates in the range of &mgr;L/min to nL/min but also to provide a signal that can be used for a servo loop or feedback control system for high pressure pumping systems.

Abstract: A method for measuring flow through an orifice using an upstream gauge pressure sensor and a downstream absolute pressure sensor determines atmospheric pressure when flow through the orifice is substantially zero, or less than a predetermined value. Then, this estimate, along with the upstream and downstream pressure sensors are used to measure flow through the orifice.

Abstract: A flow meter for use in a flow stream with a tubular housing, including a fluid inlet and a fluid outlet, in the flow stream, with the inlet pressure exceeding the outlet pressure. The interior has an orifice defined in a crystalline silicon membrane, along crystal planes of the silicon so that the geometry of the orifices is precisely known and has a sharp knife edge rim profile. Where the fluid is a gas, pressure and temperature transducers measure conditions inside of the housing for application of gas law principles. By using instantaneous pressure and temperature in the chamber, mass flow through the outlet orifices of the chamber is computed and delivered as an output signal.

Abstract: Fluid mass flow meters, particularly for measuring a wide range of relatively low flow rates of gas used in semiconductor fabrication processes include a body adapted to be interposed in a purge gas line leading to or from a mass flow controller or in a process gas line with the mass flow controller. The flow meter body includes a flow restrictor interposed in a passage and plural mass flow sensors which sense overlapping full scale fluid mass flow ranges across the flow restrictor to increase the overall range of fluid mass flow rates sensed by the meter. The flow meter body may include series or parallel arranged flow restrictors, a second set of mass flow sensors, and valving to cause a set of mass flow sensors to sense fluid mass flow rates across one or both of the flow restrictors. Embodiments of the flow meter include a pressure transducer mass flow sensor and conduits arranged with additional flow restrictors therein to selectively vary the full scale measurement range of the mass flow sensor.

Abstract: A flow device including a differential flow plate insertable into a flow path between pipe sections including a flow conduit supporting a flow interrupter and differential pressure taps. The flow conduit including a seamless interface between the flow interrupter and the pressure taps to reduce non-attributable pressure loss between differential pressure taps as well as reduce field installation labor including that of pressure testing the various pressure couplings.

Abstract: The present invention provides a method for calculating flow rate of a fluid using a pressure differential device, based on detected pressure and temperature upstream of and detected pressure adjacent a flow constriction of the pressure differential device, and calibration coefficients calculated from the results of a flow calibration performed on the pressure differential device. By incorporating the results of the flow calibration in the computation, a non-iterative method for obtaining mass flow rate is realized.

Abstract: A separator partitions an upstream side air passage of a bypass passage into first and second sub passages. A thermal flow sensor is attached to the separator facing the first sub passage. A convex is formed on the inner wall of an outer pipe defining the second sub passage. The convex protrudes toward the separator. Minimum flow passage area S2 of the second sub passage is smaller than minimum flow passage area S1 of the first sub passage, so that flow passage loss of the second sub passage is larger than flow passage loss of the first sub passage. Thus, measured air-flow amount average when the air-flow pulsates is corrected to be larger.

Abstract: An air flow measurement device includes a connector conduit with a constant inner diameter wall for the air flow, a transverse restrictor plate located within the conduit with a plurality of generally uniformly spaced apertures extending therethrough, and an annular mounting piece secured centrally about the conduit for securely mounting a pair of air pipes to the opposite ends of the conduit in air-tight engagement therewith. The restrictor plate is maintained in the connector conduit by a swaging operation which causes it to be expanded outwardly into tight engagement with the conduit wall. A pair of tank valves are mounted, by a special saddle, to the mounting piece, and passages are provided through the mounting piece and conduit wall for communication with the interior of the conduit just upstream and downstream of the restrictor plate whereby a differential pressure meter may be connected to the valves to measure the difference in pressure to thereby determine the air flow rate.

Abstract: A flowmeter used to measure the flow rate of a fluid in a conduit includes a flow restrictor insert. The conduit is coupled to an upstream and downsteam conduit portion and includes three pressure measuring stations axially spaced along the conduit wall. The flow restrictor insert includes two cylindrical portions, the second of which has a diameter larger than the first. The flow restrictor insert is positioned in the flowmeter conduit such that the first cylindrical portion is aligned with the second pressure measuring station and the second cylindrical portion is aligned with the third pressure measuring station. When a fluid flows through the conduit, the flow restrictor insert causes the fluid to diverge around the cylindrical portions thereby creating a venturi effect. The fluid flow rate is calculated from the pressure differentials derived from the data measured at the three pressure measuring stations.

Abstract: A method and device for use with a hydraulic system is adapted to measure a position, velocity and/or acceleration of a piston of a hydraulic actuator based upon differential pressure measurement. The device of the present invention utilizes a differential pressure flow sensor to establish a flow rate of a hydraulic fluid flow traveling into and out of a cavity of the hydraulic actuator, from which the position, velocity and acceleration of the piston can be determined.

Abstract: The fluid flow meter of the present invention includes a ramp inclined to the surface of a vessel so as to form a recess in the surface. A dynamic port surface extends from the lower end of the ramp to the surface of the vessel. A dynamic port is formed in the surface of the vessel, and a static port is formed in the ramp. The differential pressure between the dynamic and static ports is measured and is related to the flow velocity of fluid over the surface. The inventive flow meter has advantages of reduced drag, reduced likelihood of fouling and reduced likelihood of impact damage compared to conventional flow meters.