Abstract: There is disclosed a differential pressure sensor with a first and a second measuring chamber. Each measuring chamber being limited by a rigid carrier plate and a diaphragm plate, which is formed in the region of the measuring chamber as a pressure-sensitive measuring diaphragm. To design the differential pressure sensor to be resistant to overloading, the carrier plate is arranged between a first and a second diaphragm plate and has congruent concave depressions on opposite sides in the plane of the plate. The depressions are connected to one another by a decentered duct, penetrating the carrier plate perpendicularly to the plane of the plates. In the region of the measuring chambers, the diaphragm plates are formed congruently in relation to the depressions as pressure-sensitive measuring diaphragms. The measuring chambers and the duct are filled with an incompressible fluid.

Abstract: A pressure monitor includes a housing containing a reservoir and distributed ports. A pressure sensor is mounted inside the housing at the reservoir for measuring pressure in a liquid contained therein. A flexible membrane sealingly closes the ports and transmits external pressure to the internal liquid for measurement by the pressure sensor.

Abstract: A pressure sensor for measuring a pressure p contains a membrane with a front and a rear clamped into a body. The pressure p can be applied to the rear of the membrane. The front of the membrane is actively linked to a piston. In addition, a force transmitter is present with which a predetermined force can be applied to the piston. For the purpose of re-calibration, the membrane of the pressure sensor can be deformed by the force transmitter under precisely defined conditions and the output signal re-calibrated. A positioner can also be foreseen instead of the force transmitter.

Abstract: A method for assessing the dynamic stiffness of a flight control actuator comprising the steps of (1) providing a control surface actuator system including an actuator having a portion thereof coupled to an aircraft control surface; (2) applying a command signal to the actuator control system, causing the production of a pressure differential across the actuator in response to the command signal based on the ability of the actuator to react to an inertial load generated by the attempted acceleration of the control surface; and (3) processing a pressure signal representative of the pressure differential produced across the actuator.

Abstract: A port fitting (12, 42) is formed with a closed, pedestal end forming a diaphragm (12a, 42b) on which a strain gauge sensor (22) is mounted. A support member (16, 44) is received on the pedestal end and is formed with a flat end wall (16a, 44a) having an aperture (16c, 44c) aligned with the sensor. A portion of a flexible circuit assembly (24a, 58a) is bonded to the flat end wall. An electronics chamber is formed in a connector (18, 46) which is inverted and maintained at a selected height adjacent to the flat end wall of the support member to facilitate soldering of the flexible circuit to terminals (20, 48) in the connector and electronic components to the flexible circuit. The port fitting, when assembled to the support member, is also maintained at the selected height adjacent to the inverted connector to facilitate wire bonding the sensor to the bonded portion of the flexible circuit.

Abstract: Methods and apparatus are disclosed for accurately measuring stresses in respective membrane regions of segmented mask blanks destined to be made into masks or reticles for use in microlithography. A mask blank is held to a securing plate, e.g., by electrostatic attraction. The mask blank is held such that the struts of the mask blank contact the surface of the securing plate. The securing plate defines an array of through holes that are aligned with individual subfields of the mask blank. A pressure differential is applied across the membrane via the through-holes, causing the membrane regions to bulge. While measuring the pressure, the magnitude of bulge of individual membrane regions is measured using a displacement-measuring device. From data concerning the magnitude of bulge, membrane stress and Young's modulus are determined.

Abstract: A differential pressure sensor, for determining the differential pressure between two measuring points, comprises a pressure vessel 4 which is filled with a transfer fluid; a measuring cell which is arranged in the pressure vessel 4 and is surrounded by the transfer fluid, with two half-cells 1; a diaphragm-like deforming body 2 which separates the two half-cells 1 from each other in a pressuretight manner; two pressure supply lines 7, which respectively feed the pressure from one of the two measuring points outside the pressure vessel 4 to one of the two half-cells; and at least one pressure accumulator 6, the pressure of which acts on the transfer fluid in the vessel. Elastic or compressible bodies with a linear or degressive characteristic are suitable as the pressure accumulator 6. The pressure accumulator 6 compensates for changes in volume of the transfer fluid on account of temperature fluctuations.

Abstract: A silicon pressure sensor includes a bossed diaphragm provided with a planar surface. The bossed diaphragm converts a pressure applied to the planar surface to a force, and transmits the force through a central boss to a sensing diaphragm positioned next to the bossed diaphragm. The sensing diagram converts the force to an electrical signal. To fabricate the sensor, both diaphragms are formed in large numbers on silicon wafers and then bonded together before being separated as individual, complete sensors.

Abstract: A method for measuring multiple pressures and a pressure sensing system for accomplishing the same. The method for measuring a plurality of pressures includes, exposing each of a plurality of pressure sensors to a corresponding plurality of environments each having a corresponding pressure to be measured, determining how frequently to measure each of the plurality of pressures, determining a sequence for utilizing the pressure sensors to measure the corresponding plurality of pressures, the sequence being dependent upon the determined frequency for each of the plurality of pressures and selectively utilizing each of the plurality of pressure sensors according to the determined sequence to measure the pressure to which it is exposed.

Abstract: An arrangement for measuring a fluid pressure, comprising a pressure sensor portion (10), which is devised for accommodation in a recess (12), which is open at least at one end, wherein the pressure sensor portion (10) in relation to the recess (12) is to be dimensioned in such a way that the pressure sensor portion (10) is surrounded by a gap (14) for receiving fluid, wherein first and second surfaces (16a, 16b, 18a, 18b), which are situated on the pressure sensor portion (10) and in contact with fluid, are so dimensioned and aligned that forces, which are exerted by the fluid pressure on the first surfaces (16a, 16b) and push the pressure sensor portion (10) in the direction of the open end of the recess, are equal to or lower than the forces, which are exerted by the fluid pressure on the second surfaces (18a, 18b) and push the pressure sensor portion (10) away from the open end of the recess (12).

Abstract: A description is given of a differential pressure pickup with a small hysteresis volume which has a sensor element (1), two pressure measuring chambers (2, 3) adjacent thereto, two pressure receiving chambers (22, 32) closed off by separating diaphragms (21, 31) and two overload chambers (23, 33) separated from each other by an overload diaphragm (6), in which pickup the overload diaphragm (6) has a closed outer edge and a closed inner edge and is firmly restrained along its outer edge and its inner edge.

Abstract: A pressure differential measuring transducer has measuring membranes arranged side by side on one side of a membrane disk and a common fluid space allocated to them. To obtain a measured electric quantity which is proportional to a pressure difference and is independent of changes in static pressure with such a measuring transducer, a part of the membrane disk carrying a first measuring membrane is accommodated from the side in the interior of a tube with a seal, said tube being acted upon by a first pressure at its one end and at its other open end. Another part of the membrane disk having a second measuring membrane extends into an interior space of a container adjacent to the tube to which a second pressure can be applied.

Abstract: A pressure transmitter apparatus having a unitary body portion, separate diaphragms and flange elements and disposed within the body, a first and second normally vertical pressure passage. The first and second pressure passageways communicate respectively between first and second pressure openings extending normally horizontally through the body portion, and a transducer mounting element. The mounting element, coupled to the body portion and located above the pressure passageways, mounts a transducer that generates a differential pressure signal. One or a pair of diaphragm elements are configured to form first and second process diaphragms, closing first and second pressure openings. The flange element overlies the diaphragm element and is removably and replaceably secured to the body portion.

Abstract: A cell for converting a differential pressure into an electric signal, which comprises two chambers and a sensor. The two chambers are filled with an incompressible fluid and each are closed by a respective membrane suitable for deforming under the action of an external pressure. The chambers are separated from each other by a rigid wall. The sensor associated with the wall and responsive to the pressure difference exerted across the wall, delivers an electric signal in response thereto. At least one passage is formed between the two chambers and possesses appropriate dimensions firstly for at least attenuating a parasitic pressure difference existing across the wall at a frequency that is low or zero, and secondly for allowing the sensor to detect the pressure difference exerted across the wall at higher frequencies.

Abstract: A pressure transducer, particularly a transducer for measuring gaseous pressure differential across a chamber wall is disclosed. The transducer finds particular application in an air cleaning system. The pressure transducer of the invention is designed and arranged to include a load cell disposed between the chamber wall and a diaphragm which is designed and arranged to seal about a hole in the chamber wall.

Abstract: An air flow rate measuring apparatus includes a casing having opposite open ends, a flow rectifier mounted within the casing at an upstream-side portion thereof with respect to a direction of flow of fluid to be measured, and at least one fluid pressure detector which is mounted within the casing, and is disposed downstream of the flow rectifier, the fluid pressure detector including at least one differential pressure detector member. The differential pressure detector member includes a pair of tubular members of an identical configuration, and each of the tubular members has a flattened shape having opposed narrow side walls and opposed wide side walls, and at least one pressure-measuring port is formed through one of the opposed narrow side walls. The differential pressure detector member further includes a pair of plug members mounted on and closing opposite open ends of each of the tubular members, respectively, one of the pair of plug members having a pressure outlet port.

Abstract: A process control instrument adapted to provide an output indicative of a parameter of a process fluid is disclosed. The process control instrument is designed to be attachable to a flange having a first passageway filled with process fluid. A body of the process control instrument has an opening adjacent to the first passageway adapted to receive process fluid from the first passageway. A seal positioned in the opening and attached to the body at a seal outer diameter is adapted to prevent process fluid from leaking from the first passageway and the opening past the flange.

Abstract: A differential pressure transducer for measuring a pressure differential between a first pressure source and a second pressure source. The differential pressure transducer includes a displacement element and a sensing element coupled to the displacement element. The displacement element moves in a linear direction and deflects the sensing element to provide a signal that is proportional to the movement of the displacement element when the first and second ends are subjected to the pressures at the pressure sources. The differential pressure transducer can also include a force transfer beam that connects the displacement element and the sensing element. The sensing element can include a sensing beam and a strain gauge mounted on the beam to provide an electrical signal proportional to the strain in the beam induced by the deflection of the beam. The force transfer beam and the sensing element can be portions of a unitary member formed as a stamped part.

Abstract: A differential pressure transducer unit with an overload protection system to measure slight differential pressure in liquids and gases under high static compression loading, which unit can be connected by flanges to the differential-pressure lines. To avoid disturbing influences on the measuring element caused by radial tensions of the means of the overload protection system dependent on the absolute pressure, the measuring element is fasten in a cutout of the measuring-element housing so that it can oscillate and is free from tension. Each insulation plate is fitted with an eccentrically located measuring duct through which pressure-measuring agent flows, and which is connected at least indirectly to the measuring element.

Abstract: The first glass substrate having the first pressure admitting entrance for leading the pressure of fluid to be measured, is arranged at a side of a diaphragm of a pressure sensor, for measuring differential pressure. The second glass substrate is arranged at the side opposite to the first glass substrate, a spacer being sandwiched therebetween. The second pressure admitting entrance is formed at the second glass substrate, at the position opposite to the first presser admitting entrance of the first glass substrate. The first conductive film and the second conductive film are formed on two surfaces facing to each other, of the first and second glass substrates, respectively. By measuring the specific conductance and the dielectric constant of the object fluid between the two conductive films, these physical constants indicating the quality of the fluid, the quality of the fluid can be also detected.

Abstract: An apparatus and a method are provided for detecting accumulation of particulates in a fluid stream. A differential pressure switch is incorporated in the apparatus for detecting changes in pressure in the fluid stream passing through a strainer having a filter wherein the particulates accumulate at the filter. A body is insertable into a wall of the strainer wherein the body is in communication with the fluid stream. A pressure responsive device is responsive to changes in pressure in the fluid stream due to accumulation of the particulates. A signal producing device is activated to produce a signal upon detection of a predetermined pressure differential in the fluid.

Abstract: A temperature-compensated, self-calibrating, contact-type gaging system and method for calibrating the same. The system is configured to run in a calibration mode and a measurement mode. During the calibration mode, a unique temperature profile is generated for each particular system. The temperature offset includes offset values calculated to compensate for gaging system hardware errors as well as other measurement error caused by temperature variations encountered during gaging applications. In the measurement mode, part size measurements are adjusted by the offsets contained in the temperature profile generated for the gaging system.

Abstract: The present invention concerns a device for monitoring the pressure in at least two pressure-tight analysis vessels, that have been sealed by means of lids, whereby heat is supplied to the analysis vessels by means of a heating apparatus. The internal pressure of the analysis vessel acts on its lid. The lid is connected to a piston in a closed hydraulic system. The force, that is dependent on the internal pressure of the analysis vessel, is transferred by the lid to the piston in the hydraulic system. A lid and a piston are assigned to every analysis vessel. In addition, a stop device is assigned to each piston, whereby the stop device limits the outward movement of the piston in the event of excess pressure in the hydraulic system relative to the internal pressure of the analysis vessel. The pistons are connected to one another via the hydraulic system.

Abstract: A semiconductor pressure sensor that can be inexpensively manufactured with a reduced number of assembly steps and without using spacers includes a stem having an upper surface on which are mounted a pedestal and a semiconductor pressure sensor chip of substantially the same area as that of the stem upper surface. The semiconductor pressure sensor chip and the pedestal include aligned lead insertion holes through which leads are inserted. While spacers have been used in the prior art to reduce vacant space in the sensor that is filled with silicone oil, the spacers can be dispensed with in the invention because the semiconductor pressure sensor chip and the pedestal have areas substantially the same as the stem upper surface and serve as spacers.

Abstract: A differential pressure detecting apparatus includes a columnar main body wherein a differential pressure detection portion is inserted into a closed-end hole having a countersunk portion and formed in the outer circumferential surface of said main body at right angles to the axis of the main body, wherein a first seal diaphragm for receiving one of introduced pressures relating to a differential pressure to be measured is provided in one end surface of the main body, and wherein the main body has a hole provided for transmitting the received introduced pressure to the differential pressure detection portion; a disc-like sub-body inserted into the countersunk portion of the closed-end hole, wherein a second seal diaphragm for receiving the other introduced pressure is provided in the outer end surface of the sub-body, and wherein a hole is provided for transmitting the received introduced pressure to the differential pressure detection portion; a cover provided on the one end surface of the main body, and hav

Abstract: A control system for regulating a flow rate of a heat transfer fluid in a heat transfer system, the heat transfer system having a heat transfer fluid flow path, flow control device for creating flow along the path, a fuel source for providing a combustible fuel to the path, an air source for providing combustion air to the path, and an assembly for combusting the fuel and air, the control system comprising a sensor for sensing a measured flow value at the air source, a controller for storing an optimum flow value at the air source and for storing a range of operating control values for the flow control device, the operating control values corresponding to the optimum flow value, a system for calculating a deviation between the measured flow value and the optimum flow value, and a system for varying the operation of the flow control means in accordance with deviation.

Abstract: A pressure transmitter apparatus having a Unitary body portion, separate diaphragms and flange elements and disposed within the body, a first and second normally vertical pressure passage. The first and second pressure passageways communicate respectively between first and second pressure openings extending-normally horizontally through the body portion, and a transducer mounting element. The mounting element, coupled to the body portion and located above the pressure passageways, mounts a transducer that generates a differential pressure signal. One or a pair of diaphragm elements are configured to form first and second process diaphragms, closing first and second pressure openings. The flange element overlies the diaphragm element and is removably and replaceably secured to the body portion.

Abstract: A differential pressure transducer is provided in which first and second diaphragms are formed within a block of material, such as monocrystalline silicon. Each diaphragm carries a support for a bridge. The supports are offset from the center of the diaphragms such that deflection of the diaphragms imparts a degree of lateral motion to the respective support. The bridge is held within an evacuated cavity and the resonant frequency of the bridge is a function of the difference in pressure action of the diaphragms.

Abstract: A pressure measuring apparatus comprising a seal diaphragm that separates a fluid to be measured from a pressure transmitting medium that transmits a pressure variation of the fluid to be measured to a pressure detecting section. In such an apparatus, a non-electrically conductive film is coated on a surface of the seal diaphragm which is on the side of the fluid to be measured. As a result of the above construction, the pressure can be measured accurately over a long period of time while preventing hydrogen from passing through the seal diaphragm surely and protecting the seal diaphragm.

Abstract: A pressure sensor is capable of detecting a certain pressure and an atmospheric pressure individually and independently in real time, with miniaturization and light weight. This is attained by providing a pressure sensor comprising a first pressure sensor; and an atmospheric pressure sensor. Each sensor includes a pressure-sensitive element and a circuit for amplifying an output signal from the pressure-sensitive element. The amplifying circuit for the first pressure sensor, and the pressure-sensitive element and the amplifying circuit for the atmospheric pressure sensor are provided on the same chip. The amplifying circuit compensates for nonuniformity in characteristics of the pressure-sensitive element due to temperatures.

Abstract: A differential pressure transmitter detects a differential pressure condition of a fluid by means of a semiconductor sensor. First and second seal diaphragms are provided in a member which constitutes the differential pressure transmitter, to form first and second pressure receiving chambers. An overload protection diaphragm and first and second damper chambers are provided at positions close to the first and second pressure receiving chambers. Also, there are provided a passage for connecting the first pressure receiving chamber and the first damper chamber, a passage for connecting the second pressure receiving chamber and the second damper chamber, and passages for connecting the first and second damper chambers respectively with the semiconductor sensor. Even when a change is caused in the temperature of a processed fluid to be detected, the differential pressure transmitter quickly detects the temperature change, so that a differential pressure of the processed fluid can be measured with high accuracy.

Abstract: A method is disclosed for micromachining the surface of a silicon substrate which encompasses a minimal number of processing steps. The method involves a preferential etching process in which a chlorine plasma etch is capable of laterally etching an N+ buried layer beneath the surface of the bulk substrate. Such a method is particularly suitable for forming sensing devices which include a small micromachined element, such as a bridge, cantilevered beam, membrane, suspended mass or capacitive element, which is supported over a cavity formed in a bulk silicon substrate. The method also permits the formation of such sensing devices on the same substrate as their controlling integrated circuits. This invention also provides novel methods by which such structures can be improved, such as through optimizing the dimensional characteristics of the micromachined element or by encapsulating the micromachined element.

Abstract: A micromachined device is described receiving a pressurizable fluid has a plurality of layers bonded together along at least one bond interface, the bond interface having a terminus bordering the pressurizable fluid. In a vicinity of at least one bond interface at least one layer has a shape that reduces a stress magnitude near the bond terminus. In a preferred embodiment a width of at least one layer increases toward the bond interface, to increase the pressure at which the device can operate without fracturing. In another embodiment, both layers bordering the bond interface have widths in the vicinity of the bond interface that increase toward the bond interface. Alternately, the layers have walls shaped such that, for a reference line perpendicular to the bond interface and passing through an end of the bond interface bordering the cavity, the cavity protrudes between the reference line and at least one of the walls.

Abstract: A multi-function differential pressure sensor includes a semiconductor chip, a stationary base having a joining portion joined to a thick wall portion of the semiconductor chip, and a housing joined to the stationary base. The semiconductor chip is provided with a differential pressure detection unit, a static pressure detection unit, and a temperature detection unit. The joining portion of the stationary base is not thicker than the semiconductor chip. The stationary base has one or more thin wall portions located, in a plan view, within a circular pressure sensitive diaphragm of the semiconductor chip.

Abstract: An electronic pressure sensor (10) is enhanced by attaching a sensor die (18) to a stress isolation platform (12) using an adhesive (42) having a similar thermal coefficient of expansion. The adhesive provides a hermetic seal between the stress isolation platform and the pressure sensor die. A via (20) in the stress isolation platform provides an opening for pressure to be applied to the sensor die. The stress isolation platform is attached to a plastic package body (16) via a semi-rigid adhesive (40) for providing stress isolation and a hermetic seal between the package body and the stress isolation platform. Any hostile chemical entering the via contacts an exposed diaphragm (50) of the sensor die to assert pressure against its piezoelectric network (52) to generate the electrical signals representative of the applied pressure but are kept away from the sensitive interconnects by the hermetic seals.

Abstract: A pressure transducer is provided for measuring pressure within a measurand environment, the transducer comprising a header which includes a substantially nondeformable molded housing formed from a first thermoplastic material defining a cavity and first and second openings into the cavity and a resilient diaphragm formed from the first thermoplastic material molded to the housing and spanning the first opening; a pressure sensing device disposed within the housing; and a pressure transfer medium disposed within the cavity so as to couple the diaphragm to the pressure sensing device.

Abstract: A pressure sensor package (10) has a sensor body (12) for containing a pressure sensor. An elongated stem (14) has a first end connected to the sensor body (12), and a connector (24, 26) is disposed on a second end of the stem (14) for fixedly mounting the stem (14) to a mounting base (40), which is connected to, for example, a fuel tank (52). An annular sealing surface (28) is disposed on the first end of the stem (14) for pressing against a compressible seal (44) when the stem (14) is mounted to the mounting base (40), and an orifice (18) is disposed at the second end of the stem (14). The orifice 18 is connected to the pressure sensor by a passage (20, 22) through the stem body. The connector (24, 26) is spaced a sufficient distance from the sensor body (12) to substantially reduce error-inducing stresses on the pressure sensor.

Abstract: A pressure transducer for measuring the pressure of a fluid comprising a housing having a cavity. A diaphragm capable of displacement is located within the cavity, dividing the cavity into a first and second chamber. The first chamber is capable of receiving a fluid to be measured, typically a liquid or a gas, while the second chamber contains a liquid such as a silicon oil. The second chamber also contains a gas and means for measuring the displacement of the diaphragm. Upon pressure being exerted against the diaphragm from the fluid, the diaphragm displaces against the liquid and gas, compressing and dissolving the gas as pressure is increased. Displacement of the diaphragm is measured by a measuring device, such as a strain gauge. When the gas is fully dissolved, further movement of the diaphragm is limited by the compressibility of the liquid.

Abstract: A pneumotach gas flow transducer having strain gauge pressure transducers disposed therein for disposition in a selected element or component of a ventilatory circuit. A differential pressure is communicated from the upstream and downstream sides of a flow restrictor in the element's passageway to the transducers via a barrier medium which fills holes in the element and contacts the transducer elements.

Abstract: A transducer having a plurality of sensing elements disposed in a single diaphragm wherein each of the sensing elements is spaced from every other of the sensing elements a predetermined distance so as to control interference among the sensing elements. Each of the sensing elements preferably comprises a plurality of piezoresistors each of which are coupled in a Wheatstone bridge configuration. This transducer achieves sensitive, accurate, high spatial resolution measurements of non-uniform pressures.

Abstract: A catheter sensor assembly and support has a member with a distal end and a proximal extension joined by an intermediate part. An open passage extends along the proximal extension and across the intermediate part to carry a sensor overlaying the passage. Conductors attach to the sensor bottom for transmitting signals from the sensor through a catheter lumen. An adhesive sealant secures the sensor to the intermediate part near the distal end so that the passage remains open between the lumen and the bottom. A method for assembling and supporting a sensor at a distal end of a catheter tube includes steps of attaching a sensor with an area toward an end connected to electrical conductors, placing a tube in the passage to provide a passageway between the lumen and the sensor, mounting the sensor to the member overlying the passage, inserting the proximal extension into the lumen with the electrical conductors passing through the lumen and sealing the sensor to the passage.

Abstract: An apparatus for the accurate measurement of pressure changes has a reference accumulator and a differential pressure transducer. The reference accumulator stores a pressure representative of the environment being measured. The differential pressure transducer measures the difference between the reference pressure and the pressure of the environment being measured. Connected to the reference accumulator is a valve that allows the reference accumulator to be charged to a pressure representative of the environment being measured and provides protection to the differential pressure transducer from overpressuring. This valve can be controlled remotely by electrical means. With the use of an isolation means, such as an isolation bellows, the whole apparatus can be protected from the environment being measured.

Abstract: The negative pressure monitor is intended for use in combination with an IV administration set, for monitoring venous, arterial and other physiological pressure signals. The system provides a coupling mechanism with a sealed vacuum chamber between a fluid chamber in communication with the fluid in line, and the pressure transducer. The vacuum in the coupling mechanism serves not only to communicate pressure changes within the fluid chamber to the pressure transducer, but also functions to maintain the fluid chamber in pressure communication with the pressure transducer.

Abstract: An improved diaphragm probe comprising a plate having a portion removed to form one or more cavities. At least two diaphragm strips sealed to close off each of the external openings of each of said one or more cavities. An incompressible fluid filling each cavity. A pressure sensitive instrument and means to transmit pressure changes at the diaphragms to said instrument in order to maximize the active diaphragm area with relation to the entry dimensions of the probe into a conduit.

Abstract: A differential pressure sensing means and method includes an inlet receiving a fluid having a first pressure. Another inlet receives a fluid having a second pressure. A plurality of pressure sensing devices are connected to the first and second inlets. Each pressure sensing device senses a pressure differential within a different predetermined range of pressures and provides a pressure signal representative thereof. An output circuit connected to the plurality of pressure signals provides a pressure signal selected from one of the signals provided by the plurality of pressure sensing devices so as to provide a pressure signal representative of the pressure difference between the first and second pressures of the fluids.

Abstract: A compact catheter assembly provides for the communication of a reference pressure to a pressure-sensing transducer by forming a passageway between spaced electrical conductors mounted on a planar dielectric substrate. The cathter assembly also provides for the operative mounting of multiple transducers onto a single catheter tip by employing a plurality of planar dielectric substrates, each having an array of electrical conductors, stacked atop one another so as to protrude longitudinally from the end of the catheter bore at different distances. A plurality of electrical transducers protrude longitudinally in series from the bore overlying the substrates.

Abstract: An isolator apparatus for coupling pressure from a pressurized fluid carried in a conduit to a pressure sensor in a pressure transmitter having an isolation diaphragm, isolation fluid, and a pressure sealing ring for providing an annular seal around an active region of the isolation diaphragm. The isolator apparatus includes a rigid support for spacing the pressure sealing ring away from the active region which reduces pressure measurement errors related to temperature-induced isolation fluid expansion, such that the annular seal overhangs the isolation diaphragm's active region.

Abstract: A method and apparatus for ensuring accurate measurement of blood pressure regardless of the position of the sensing transducer relative to the position of the patient's heart. The method and apparatus provides a hydrostatic balancing system in which a column of fluid is used to offset the hydrostatic pressure created by the corresponding column of blood contained in the blood vessel in the limb upon which the measurement is being taken. A flexible tube is routed along the patient's limb with one end being positioned at heart level and the other end terminating at the occlusion cuff which supports the pressure sensing transducer. The tube is filled with fluid and is connected to a fluid reservoir chamber located at approximately the same level as the patient's heart. The hydrostatic pressure created by the fluid in the tube effectively balances the corresponding hydrostatic pressure created by the blood in the blood vessel.

Abstract: A range spring assembly for a differential pressure responsive device which includes a spring retainer plate configured for coaction with a movable portion of a device, such as a bellows or diaphragm. A flat spiral spring in spaced relation to the retainer plate is provided with a clamp disc. A plurality of helical range springs are equiangularly disposed about a circumference inwardly of the periphery of the retainer plate, each of the range springs having a first end thereof securely attached to the retainer plate adjacent the center thereof, with the other ends being selectively attachable to the clamp disc, whereby the range may be readily established by locking one or more ends of the helical springs for providing the desired spring bias for the selected range.

Abstract: A fluid drainage system includes a suction chamber and a collection chamber. The suction chamber includes a suction regulator comprised of first and second chambers separated by a divider. An opening in the divider has a biased closing member associated therewith for opening or closing the opening according to the pressure differential between the chambers. A dash pot is connected to the closing member for damping the force on the closing member. The drainage system further includes devices for measuring the patient airflow, patient negativity and imposed suction. Those devices consist of diaphragms having dials connected thereto such that movement of the diaphragm results in movement of the dial and thereby indicating a change in one of the above noted variables. As an alternative, the drainage system includes a venturi meter for measuring airflow. Finally, the system contains an anti-spill device that prevents the spilling of fluids from the collection chamber to other chambers in the device.