Abstract: A method and device for the measurement of dissolved gas within a fluid. The fluid, substantially a liquid, is pumped into a pipe. The flow of the fluid is temporally restricted, creating one or more low pressure regions. A measurement indicative of trapped air is taken before and after the restriction. The amount of dissolved air is calculated from the difference between the first and second measurements. Preferably measurements indicative of trapped air is obtained from one or more pressure transducers, capacitance transducers, or combinations thereof. In the alternative, other methods such as those utilizing x-rays or gamma rays may also be used to detect trapped air. Preferably, the fluid is a hydraulic fluid, whereby dissolved air in the fluid is detected.

Abstract: A differential force sensor method and apparatus for automatically monitoring manual injections through an intravenous line. The differential force sensor includes two piezoresistive sense die that are packaged in close proximity utilizing a number of packaging processes. The two piezoresistive sense die can be utilized to measure forces exerted on a diaphragm on either side of an orifice. The piezoresistive sense die can be packaged in close proximity to make intimate contact with the diaphragms on either side of the orifice. The differential force sensor further includes two plungers that make intimate contact with the diaphragm and transfer the force into the piezo-resistive sense dies. Additionally, one or more ASICs and microcontrollers can be utilized to provide thermal calibration and differential calculation.

Abstract: A flow measuring device has a flow channel block including a main flow channel whose both ends are open, and an auxiliary flow channel that branches from the main flow channel, a flow amount measurement element provided for the auxiliary flow channel, and a branch entrance and a collection exit that open in a wall surface of the main flow channel, and that communicate to the auxiliary flow channel, so that a part of a gaseous body that flows through the main flow channel is directed to the auxiliary flow channel through the branch entrance, and the gaseous body that has passed through the auxiliary flow channel is directed back to the main flow channel through the collection exit. A holding member containing portion is provided in a depressed manner for an area excluding an area including the branch entrance and an area including the collection exit in a circumference surface of a space of the flow channel block that configures the main flow channel. An orifice is contained within the main flow channel.

Abstract: A system for monitoring non-volatile residue concentrations in ultra pure water includes a nebulizer for generating an aerosol composed of multiple water droplets, a heating element changing the aerosol to a suspension of residue particles, and a condensation particle counter to supersaturate the dried aerosol to cause droplet growth through condensation of a liquid onto the particles. The nebulizer incorporates a flow dividing structure that divides exiting waste water into a series of droplets. The droplets are counted to directly indicate a waste water flow rate and indirectly indicate an input flow rate of water supplied to the nebulizer. The condensation particle counter employs water as the condensing medium, avoiding the need for undesirable chemical formulations and enabling use of the ultra pure water itself as the condensing medium.

Abstract: Systems and methods for metering fluid flow are disclosed. A valve may generally include an orifice plate, and a disc positioned adjacent to the orifice plate. An orientation of the disc relative to the orifice plate is adjustable to regulate a fluid flow rate through the valve. An effective area of an aperture in the orifice plate may be manipulated to adjust the fluid flow rate. In some configurations, the valve may provide sonic flow control or differential pressure regulation. In some applications, a controller may adjust the orientation of the disc relative to the orifice plate to maintain a substantially constant pressure drop across the orifice plate in order to determine a fluid flow rate through the valve.

Abstract: There is provided a housing for a flow conditioner. The housing comprises a body having first and second pipe connections, a flow passage between the pipe connections, a carrier receiving cavity within the flow passage, and an opening corresponding to the carrier receiving cavity. A plate carrier has a sealing portion and a flow conditioner carrying portion. The sealing portion has a sealing surface for sealing the opening corresponding to the carrier receiving cavity, and the flow conditioner carrying portion depends from the sealing portion. The flow conditioner carrying portion is sized to be inserted through the opening and into the carrier receiving cavity, and has a plurality of set screw receiving apertures or a retaining lip for securing the flow conditioner. There is a connector for securing the plate carrier within the body such that the sealing surface seals against the body.

Abstract: The present invention refers to a flow sensor with double obstruction disclosing a simple and innovative structure, able to promote a series of advantages and new technical effects from the combination of fixed and variable obstruction elements. More particularly, the present invention comprises a front main body (12) and a main body (40) fitted to each other so to press two obstruction elements, the first one being fixed (30) and the second being variable (50), so to increase sensitivity and reduce the annoying noise, being especially useful to monitor patients for long periods.

Abstract: A flow rate ratio variable type fluid supply apparatus includes a flow rate control system supplying gas of flow rate Q that is diverted to first flow diverting pipe passage and second flow diverting pipe passage with prescribed flow rates Q1/Q0 so gas is supplied to a chamber, and a first orifice having opening area S1 is installed on the first flow diverting passage, and the second flow diverting passage is connected to a plurality of branch pipe passages connected in parallel, orifices having opening area installed on the branch passages, and open/close valves installed on all, or some of, the branch passages so gas is diverted to flow diverting passages with flow rate ratio Q1/Q0 equivalent to the ratio of the first orifice and the total opening area S2o of flow passable orifices of the second flow diverting passage by regulating total opening area of the flow passable orifices.

Abstract: A pressure sensor having a structure in which compressible fluid is prevented from stagnating in the vicinity of a pressure-receiving surface of the pressure sensor in the interior of a pressure introducing portion is provided. In a pressure sensor including a sensor body arranged in a pressure introduction flow channel branched in a T-shape upward from a primary fluid flow channel in which fluid to be subjected to pressure measurement flows, the pressure introduction flow channel includes an inclined surface extending in a direction to increase an opening area on the side of an inlet port of the fluid on a wall surface on the downstream side in terms of the direction of flow of the fluid.

Abstract: A tilt sensor is provided that is generally adapted to detect tilted and non-tilted stated of an object associated therewith, which in some cases is a ventilation circuit component. The tilt sensor may correspond to a pneumatically operated tilt sensor that can be used in conjunction with a ventilator to help prevent compromised measurements from certain elements which can be used in a ventilator patient circuit.

Abstract: A flow meter device that features a way to obtain an accurate differential pressure across an orifice body situated in line with the flow of gas and liquids. The orifice body is held in place by sealing components integrated into the orifice body. The differential pressure is sensed via openings incorporated into the body of the device, upstream and downstream of the orifice body. The device with its improved accuracy may be used for small and large applications measuring flow. The device 31 is comprised of a meter body 32; an orifice disk 43 with features; a sealing means 50; a cover means 33, and a means to secure the device 31 into a fluid stream where the device 31 may be used to easily and accurately measure fluid flow in a pipe.

Abstract: An element of an averaging orifice plate fluid flow meter for measuring the volumetric rate of fluid flow in a conduit having an interior circumference for carrying a flow of fluid comprising, a planar flow impedance plate for disposition transversely across the interior of the conduit and perpendicular to the fluid flow, a plurality of spaced apart orifices disposed in the plate where the profile of each orifice is a segment of a circle on an arc where the arc is coincident with a portion of the interior circumference of the conduit.

Abstract: Methods and apparatus enable measuring flow of a fluid within a conduit. For example, flowmeters may measure the velocity of production fluid flowing through production pipe of an oil/gas well. The flowmeters rely on detection of pressure variations generated as a result of a backward-facing step as a basis for flow measurement calculations. Pressure sensing occurs away from the step in a direction of the flow of the fluid in an enhanced turbulence region of the flowmeter where the inner diameter remains enlarged as a result of the step.

Abstract: A differential-pressure flow meter is capable of easily eliminating adhesion to an orifice of an extraneous material. The differential-pressure flow meter includes: a pair of pressure sensors provided on a straight pipe part of a main fluid channel; an orifice unit interposed between the pair of pressure sensors; a columnar orifice body provided on the main fluid channel to be detachable in a direction orthogonal to a flow direction of a fluid in the main fluid channel; and an orifice hole penetrating the orifice body in the flow direction of the fluid, wherein the orifice body is rotatable at a prescribed installation position to reverse an upstream side and a downstream side with respect to the orifice hole, and flow rate measurement is performed by converting into a flow rate a difference in pressure that is obtained from two pressure values sensed respectively by the pair of pressure sensors.

Abstract: An orifice fitting having a drainage system. In some embodiments, the orifice fitting includes a housing having a chamber therein, a flow path extending through the chamber, an orifice plate moveable between a first position in the flow path and a second position outside of the flow path, and a rotatable shaft extending through the housing into the chamber. The shaft has a flowbore extending between a first fluid inlet in fluid communication with the chamber and a fluid outlet formed adjacent the end of the shaft.

Abstract: A flow sensor includes a detector provided on a side surface of a body formed in a tubular shape. First and second passages formed in the interior of the body communicate with an introduction passage of the detector via first and second sensor passages. The first and second sensor passages penetrate through and open respectively on first and second projections, which project at predetermined heights from an inner circumferential surface of the body, communicating with the first and second passages. A fluid, which flows from the first passage and into the first sensor passage, after being guided to the introduction passage and the flow rate thereof detected by a detector, flows through the second sensor passage and into the second passage.

Abstract: A disposable assembly for use with a sensor assembly, and method for making the same, the disposable comprises a body, a flow restricting element, and a fluid pressure membrane. The body has a lid portion and a base portion. The body defines a fluid flow passage that forms an inlet and an outlet. The flow restricting element is positioned along the fluid flow passage between the inlet and the outlet. The fluid pressure membrane is at a location in the fluid flow passage between the inlet and the outlet. The fluid pressure membrane defines an opening for receiving the flow restricting element. The fluid pressure membrane is located between the lid portion and the base portion of the body.

Abstract: In an adaptor for a flow sensor, a tubular body is adapted to allow respiratory gas to pass through. At least one fluid-resistant member is disposed in the tubular body. At least two pairs of first passages are formed in the fluid-resistant member and adapted to lead out pressures at two positions in the tubular body which are to be detected by the flow sensor.

Abstract: Methods and apparatus enable measuring flow of a fluid within a conduit. For example, flowmeters may measure the velocity of production fluid flowing through production pipe of an oil/gas well. The flowmeters rely on detection of pressure variations generated as a result of a backward-facing step as a basis for flow measurement calculations. Pressure sensing occurs away from the step in a direction of the flow of the fluid in an enhanced turbulence region of the flowmeter where the inner diameter remains enlarged as a result of the step.

Abstract: An element of an averaging orifice plate fluid flow meter for measuring the volumetric rate of fluid flow in a conduit having an interior circumference for carrying a flow of fluid comprising, a planar flow impedance plate for disposition transversely across the interior of the conduit and perpendicular to the fluid flow, a plurality of spaced apart orifices disposed in the plate where the profile of each orifice is a segment of a circle on an arc where the arc is coincident with a portion of the interior circumference of the conduit.

Abstract: A compact differential-pressure flow meter with reduced wiring is provided. The differential-pressure flow meter has first and second pressure sensors 12A and 12B fixed to a base member 14 on upstream and downstream sides of an orifice member 11 along a flow channel to determine a flow rate based on a pressure difference measured between the two sides of the orifice member 11 by the pressure sensors. The differential-pressure flow meter includes specific control boards disposed near pressure-sensing parts installed in the respective pressure-sensing device and a main control board disposed in a board installation space formed inside the base member. The specific control boards are connected to the main control board with wires passing through a plurality of wiring conduits provided in housings of the pressure-sensing device, and external wiring are connected to one of the specific control boards or to the main control board.

Abstract: Methods and apparatus for extracting gas samples from a particle-laden fluid stream are disclosed. An exemplary sampling probe apparatus includes a probe head having an upstream face and a downstream face, an intake orifice inwardly tapering from the upstream face into a central bore region of a cavity within the probe head, and an outlet orifice outwardly tapering from said central bore region to the downstream face, so as to permit fluid gas flow through the central bore region of the cavity. A filter device disposed within the cavity of the probe head extends between the intake orifice and the outlet orifice so as to divide a low-pressure sampling region of the cavity from the central bore region. A sampling tube in fluid communication with the low-pressure sampling region provides for extracting gas samples from the low-pressure sampling region of the cavity.

Abstract: Methods and apparatus enable measuring flow of a fluid within a conduit. For example, flowmeters may measure the velocity of production fluid flowing through production pipe of an oil/gas well. The flowmeters rely on detection of pressure variations generated as a result of a backward-facing step as a basis for flow measurement calculations. Pressure sensing occurs away from the step in a direction of the flow of the fluid in an enhanced turbulence region of the flowmeter where the inner diameter remains enlarged as a result of the step.

Abstract: A device for controlling fluid flow pressure and flow rate is disclosed. The device includes a first orifice plate, a second orifice plate housed in a tubular structure. The first orifice plate includes a first orifice of a first diameter (d1) and the first orifice is positioned near an edge of the first orifice plate. The second orifice plate includes a second orifice of a second diameter (d2) and the second orifice is positioned near an edge of the second orifice plate. The tubular structure has an effective diameter (D) comprising the first orifice plate and the second orifice plate placed at perpendicular direction to the fluid flow within the tubular structure, separated by an optimum distance (X).

Abstract: A flow meter filter system (200) according to an embodiment of the invention includes a noise pass filter (203) configured to receive a first version of a flow meter signal and filter out the flow meter data from the flow meter signal to leave a noise signal, a noise quantifier (204) configured to receive the noise signal from the noise pass filter (203) and measure noise characteristics of the noise signal, a damping adjuster (205) configured to receive the noise characteristics from the noise quantifier (204) and generate a damping value based on the noise characteristics, and a filter element (206) configured to receive a second version of the flow meter signal and receive the damping value from the damping adjuster (205), with the filter element (206) being further configured to damp the second version of the flow meter signal based on the damping value in order to produce a filtered flow meter signal.

Abstract: A differential pressure based flow sensor assembly and method of using the same to determine the rate of fluid flow in a fluid system. The sensor assembly comprises a disposable portion, and a reusable portion. A flow restricting element is positioned along a fluid flow passage between an inlet and an outlet. The disposable portion further has an upstream fluid pressure membrane and a downstream fluid pressure membrane. The reusable portion has an upstream fluid pressure sensor and a downstream fluid pressure sensor. The upstream fluid pressure sensor senses the upstream fluid pressure at a location within the fluid flow passage between the inlet and the flow restricting element. The downstream fluid pressure sensor senses the downstream fluid pressure at a location within the fluid flow passage between the flow restricting element and the outlet. The process utilizes output of the sensors to calculate the flow rate of the fluid.

Abstract: A process fluid pressure transmitter includes a process fluid pressure sensor, measurement circuitry, a controller and a loop communicator. The process fluid pressure sensor has an electrical characteristic that varies with process fluid pressure. The pressure sensor is coupleable to a source of process fluid pressure. The measurement circuitry is coupled to the process fluid pressure sensor and provides a signal indicative of the electrical characteristic of the process fluid pressure sensor. The controller is coupled to the measurement circuitry and receives the signal and calculates a process fluid pressure based at least in part upon the signal. The controller is also configured to detect a process fluid pressure transient and store at least one parameter related to the process fluid pressure transient. The loop communicator is coupled to the controller and is configured to provide a signal over a process communication loop based upon the process fluid pressure.

Abstract: An improved flow measuring device, such as a mass flow meter or mass flow controller, providing a high turn-down ratio as compared to prior art devices. In accordance with various embodiments of the invention, a flow sensor includes a sensor flow path that includes one or more restrictions configured to provide the sensor flow path with a non-linear relationship between a pressure drop across the sensor flow path and the flow of fluid through the flow sensor conduit. Such a flow sensor preferably achieves a high turn-down ratio by way of a variable bypass ratio that is directly proportional to the sensor tube mass flow rate so that the turn-down ratio of the mass flow controller will be ideally proportional to the square of the turndown achievable by the flow sensor conduit fluid sensing portion alone. In some embodiments, the restriction can be employed as a part of a fluid seal having an orifice and disposed between a flow sensor portion of a flow meter and a bypass portion of the flow meter.

Abstract: A simple, passive and rugged device for measuring the flow rate of liquid. A variable area obstruction valve, a differential pressure sensor and a densitometer are combined in a single housing to provide for a highly accurate and precise measure of mass flow.

Abstract: The present invention refers to a flow sensor with double obstruction disclosing a simple and innovative structure, able to promote a series of advantages and new technical effects from the combination of fixed and variable obstruction elements. More particularly, the present invention comprises a front main body (12) and a main body (40) fitted to each other so to press two obstruction elements, the first one being fixed (30) and the second being variable (50), so to increase sensitivity and reduce the annoying noise, being especially useful to monitor patients for long periods.

Abstract: In an adaptor for a flow sensor, a tubular body is adapted to allow respiratory gas to pass through. At least one fluid-resistant member is disposed in the tubular body. At least two pairs of first passages are formed in the fluid-resistant member and adapted to lead out pressures at two positions in the tubular body which are to be detected by the flow sensor.

Abstract: A process flow device that includes a self-averaging orifice plate type of primary flow element with a high pressure tap located on or incorporated into its upstream surface, and a low pressure tap located on or incorporated into its downstream surface, for measuring, by a differential pressure process, the volumetric rate of fluid flow at a point in a fluid carrying conduit where the velocity profile of the fluid is asymmetric with respect to the longitudinal axis of the conduit. The improved pressure tap configuration consists of two fluid conduits, one carried by each of the downstream and upstream faces of the orifice plate, establishing fluid communication between openings in the downstream and upstream faces of the orifice plate and their respective terminal pressure ports.

Abstract: A device and method for calibration of a mass flow sensor (14) employs a flow channel and a holder for the mass flow sensor in the flow channel. An adjustable throttle device is provided between the holder and a connection to a pump during a calibrating operation to operate on the basis of a predetermined time/displacement profile by means of a control device. During operation of the pump, the throttle device generates a supercritical flow with which a flowing medium has the speed of sound in the narrowest cross section of the throttle device.

Abstract: An industrial pressure transmitter, for use in industrial process control systems, comprises a differential pressure sensor and an integrated process connector connected to the differential pressure sensor. A process fluid flow duct extends through the process connector and receives an industrial process fluid. A primary element is positioned in the process fluid flow duct for producing a pressure differential in the process fluid across the primary element. The differential pressure sensor is connected to the process fluid flow duct to sense the pressure differential across the primary element.

Abstract: Provided are an orifice member, and a differential-pressure flow meter and a flow-regulating device using the orifice member, that allow purging to be carried out easily when changing the fluid to be circulated, that are less likely to cause contamination and leaching of impurities to the circulated fluid, and that can be easily produced. The flow-regulating device includes a first pressure-measuring device (object to be connected to) that is connected to one end of the orifice member, and a second pressure-measuring device (object to be connected to) that is connected to the other end of the orifice member, and a flow-regulating valve that is connected to the downstream side of the differential-pressure flow meter, which includes the above-mentioned units.

Abstract: A gas monitoring system that comprises a sensor, a first valve, and a second valve. The sensor is disposed within a sensor housing that has an inlet and an outlet. The sensor generates a signal based on a characteristic of a gas within the housing. The first valve is disposed at the inlet. The second valve is disposed at the outlet. The first valve and the second valve open and close based on an orientation of the sensor housing.

Abstract: A process device providing total fluid flow control is provided. The device includes a closure mechanism disposed in a flow conduit. The closure mechanism, which is preferably an iris-type diaphragm, provides a variable internal diameter. The device includes a differential pressure sensor for sensing the differential pressure on opposite sides of the diaphragm. A controller receives an indication of differential pressure and generates a control signal to an actuator that actuates the closure mechanism. The closure mechanism, differential pressure sensor and controller create a closed-loop flow controller in a single process device.

Abstract: A flow meter filter system (200) according to an embodiment of the invention includes a noise pass filter (203) configured to receive a first version of a flow meter signal and filter out the flow meter data from the flow meter signal to leave a noise signal, a noise quantifier (204) configured to receive the noise signal from the noise pass filter (203) and measure noise characteristics of the noise signal, a damping adjuster (205) configured to receive the noise characteristics from the noise quantifier (204) and generate a damping value based on the noise characteristics, and a filter element (206) configured to receive a second version of the flow meter signal and receive the damping value from the damping adjuster (205), with the filter element (206) being further configured to damp the second version of the flow meter signal based on the damping value in order to produce a filtered flow meter signal.

Abstract: An orifice plate for use in a conduit through which fluid flows is defined by a central circular region having a radius R0 and a ring-shaped region surrounding the central circular region. The ring-shaped region has holes formed therethrough with those holes centered at each radius R thereof satisfying a relationship AR=a/(XRVRb) where AR is a sum of areas of those holes having centers at radius R, XR is a flow coefficient at radius R, VR is a velocity of the fluid that is to flow through the conduit at radius R, b is a constant selected to make at least one process variable (associated with the fluid that is to flow through the conduit) approximately equal at each radius R, and a is a constant that is equal to (XRARVRb) at each radius R.

Abstract: Microfluidic devices, systems, and methods measure viscosity, flow times, and/or other flow characteristics within the channels, and the measured flow characteristics can be used to generate a desired flow. Multi-reservoir pressure modulator and pressure controller systems, electrokinetic systems and/or other fluid transport mechanisms can generate the flow, controllably mix fluids, and the like.

Abstract: A wafer for placement in a pipe. The wafer includes a housing having an outer surface and an orifice adapted to allow fluid flowing in the pipe to pass through the housing. The housing has at least a first port extending into the housing from the outer surface for holding a first acoustic transducer. The wafer includes means for attaching the housing to the pipe. A method for obtaining information about fluid in a pipe.

Abstract: An exhaust gas recirculation system directs exhaust gasses from an exhaust manifold to an intake manifold of an internal combustion engine. The exhaust gasses travel from the exhaust manifold, first passing through a flow control valve and then through a measuring orifice before entering the intake manifold. Pressure upstream of the orifice is used, along with correction pressure downstream of the orifice, to measure and control exhaust gas flow. Further, manifold pressure is determined from downstream pressure and the used along with the measured exhaust gas flow to calculated a cylinder air charge amount.

Abstract: A Rotary Air-data System (RADS) periodically samples pressure data from a main rotor blade mounted pitot-scoop integrated with a high accuracy pressure sensor to compute a velocity vector that is resolvable into the aircraft's coordinate system. Mathematical techniques are employed which provide accurate computations of static pressure without a static pressure sensor. The RADS also computes the direction of the relative wind which is particularly useful when the pilot executes hover or low speed, low altitude maneuvers in restricted visibility. The availability of relative wind velocity information coupled with navigation data enhances the ability of rotary aircraft to perform accurate low altitude hover, fire control and other autopilot maneuvers.

Abstract: Methods and apparatus for a bi-directional dual chamber orifice fitting comprising a body with a chamber in fluid communication with a flow bore. The fitting also comprises an orifice supported by an orifice plate carrier that is selectably disposable in the bore. In the preferred embodiment, the lower chamber includes two passageways connecting the chamber to the flow bore. One passageway is located on either side of the orifice plate. Each passageway may also be equipped with a check valve to permit flow in only one direction through the passageway. In operation, the passageway on the upstream side of the orifice would allow fluid to flow into the lower chamber while the passageway on the downstream side would prevent flow back into the flow bore.

Abstract: A method and an apparatus for measuring the concentrations of the components of a fluid are described, which can be used to measure the concentrations of the components continuously in real time and to monitor a high pressure gas, and is suitably used for in-line monitoring. In the method and the apparatus, a fluid sample is conducted through a measuring tube, wherein the measuring tube has a small aperture with a constant diameter in a fluid flow path. The pressure difference (P1?P2) between the upstream and the downstream of the small aperture and the flow rate at the downstream of the small aperture are measured to determine the concentrations of the components of the fluid.

Abstract: A method and an apparatus for measuring the concentrations of the components of a fluid are described, which can be used to measure the concentrations of the components continuously in real time and to monitor a high pressure gas, and is suitably used for in-line monitoring. In the method and the apparatus, a fluid sample is conducted through a measuring tube, wherein the measuring tube has a small aperture with a constant diameter in a fluid flow path. The pressure difference (P1−P2) between the upstream and the downstream of the small aperture and the flow rate at the downstream of the small aperture are measured to determine the concentrations of the components of the fluid.

Abstract: A coupling having an integral orifice plate engages upstream and downstream segments of a landfill piping system. Upstream and downstream ports are respectively formed through the walls of the coupling adjacent the orifice plate. The difference in pressure at the ports is correlated to a flow rate through the pipe. Sensor fittings are threadably engaged with the ports, and to support the threadable engagement, the wall of the coupling through which the ports are formed has a thickness of at least around one-half inch.

Abstract: Microfluidic devices, systems, and methods measure viscosity, flow times, and/or other flow characteristics within the channels, and the measured flow characteristics can be used to generate a desired flow. Multi-reservoir pressure modulator and pressure controller systems, electrokinetic systems and/or other fluid transport mechanisms can generate the flow, controllably mix fluids, and the like.

Abstract: The present invention provides a high-performance mass flow controller which is compact and lightweight, which has a flow path having a simple structure and which does not have dead space in which a fluid is likely to stagnate and cause the problem of contamination. A cylindrical valve conduit having a hollow structure, a yoke and a sensor conduit are connected in tandem. A fluid inlet portion is connected to an end of the valve conduit and a fluid outlet portion is connected to an end of the sensor conduit. A solenoid valve is provided on a side of the fluid inlet portion and a thermal mass flowmeter is provided on a side of the fluid outlet portion. In the valve conduit, a cylindrical plunger providing a movable portion of the solenoid valve and a valve portion of which a degree of opening is adjusted by moving the plunger are provided on a side of the fluid inlet portion. A bypass for generating a laminar flow is disposed in the sensor conduit so as to effect one-way flow of a fluid.

Abstract: A gas mass flow meter includes an elongated channel extending through a high thermal mass body and a critical flow nozzle in a downstream portion of the channel. A heat exchanger is provided upstream in the channel. Gas is forced through the heat exchanger and the critical flow nozzle at a flow rate of up to 5000 slm and at sufficiently high-pressure to ensure critical flow of the gas through the critical flow nozzle. The heat exchanger brings the gas close to the temperature of the high thermal mass body. The pressure of the gas is measured upstream and downstream from the nozzle and the temperature of the gas emerging from the heat exchanger is measured. The mass flow rate of gas through critical flow nozzle is computed from the upstream pressure, downstream pressure, temperature of the high thermal mass body, density of the gas, and a dimensional characteristic of the critical flow nozzle.