Abstract: The invention relates to a pressure sensor (1), comprising a housing (2), a housing element (3) which may be exposed to a pressure chamber (10), mounted on the housing (2) by means of a metallic membrane (5) and a measuring cell (4) which can indirectly measure a pressure acting on the housing element (3) and transmitted to the measuring cell (4) as a force resulting therefrom. According to the invention, said pressure sensor (1) comprises a housing element (3) embodied as a pin and projects out of the housing (2). The advantage of such an arrangement is only a small drilling to a pressure chamber (10) need be provided, in order to carry out a pressure measurement. The pin (3) need only be so long that the front end thereof, in the assembled state, approximately reaches the wall (11) of the pressure chamber (10).

Abstract: An arrangement for filtering a hydraulic fluid having a bypass line connecting the feed channel to the discharge channel where the bypass line is opened by a pressure switching valve when a pressure change is caused by the contamination of the filter element.

Abstract: A pressure gauge is composed of two separate components adapted to be assembled and disassembled by hand. The one component is a pressure-motion conversion element (3, 6) for receiving a pressure and effecting a movement of a movable portion (3c, 6c) thereof in response thereto, and the other component is a force measuring element (5) for measuring a force caused due to the movement of the movable portion (3c, 6c). The pressure-motion conversion element (3, 69) is constructed as a disposable component, whereas the force measuring element (5) is intended for re-use.

Abstract: The present invention relates to apparatuses for detecting fuel pressure in internal combustion engines. The invention especially relates to internal combustion engine applications in which fuel reaches a high pressure. The apparatus according to the invention is a simple switch apparatus. In the apparatus the fuel pressure moves a piston causing a switching operation in the apparatus, which in turn can be detected by means of a separate detector.

Abstract: A fluid system pressure indicator is adapted for use in fluid systems having a filter element. The fluid system force indicator includes a housing partitioned to be exposed to the fluid system to provide transmission of a mechanical force between these partitioned environments to indicate the fluid pressure. This exterior shape change is such that it can be identified through tactile means not requiring visual identification.

Abstract: A differential pressure indicator and method of configuring a differential pressure indicator is provided. The differential pressure indicator is configurable to provide open circuit or closed circuit logic and includes a housing, a pressure responsive element, a post, first, second and third electrical contacts and an electrical insulator from an insulative material. The electrical insulator separates the third electrical contact from either the first contact or the second contact to provide a desired type of logic. The differential pressure indicator may use substantially similar components to provide either open circuit or closed circuit logic or the components may be rearranged to provide either open circuit or closed circuit logic.

Abstract: A hydraulic accumulator includes an accumulator housing (1) formed of a non-magnetizable material and defining an axial direction of the housing. A separating element (9) can be axially displaced in the accumulator housing (1) and separates two working chambers (5, 7) from each other in the accumulator housing (1). A field-generating magnetic configuration (29) is arranged on the separating element. A series of magnetic field sensors (35) are arranged on the outer side of the accumulator housing (1), extend along the path of the axial movement of the separating element (9) and react to the field of the magnetic configuration (29) on the separating element (9) to characterize its position along the series of magnetic field sensors (35).

Abstract: A standard industrial pressure gauge is adapted for a sanitary conduit that has been provided with a tubular stub for mounting the gauge. A cylinder has a disk flange that mates with an upper flange of the tubular stub. A cap closes off the top of the cylinder, and a female threaded nipple is affixed on the cap over an aperture through the cap. A piston has one or a pair of O-ring seals seated on the circumferential surface of the piston, with the piston having at least a limited range of motion within the cylinder. The gauge is fitted into the threads of the nipple, and the space above the piston and through the aperture and the nipple is filled with an incompressible fluid. In one embodiment, there is a leak detector hole in the cylinder wall aligned with the space between the two O-rings.

Abstract: A fluid system pressure indicator is adapted for use in fluid systems having a filter element. The fluid system force indicator includes a housing partitioned to be exposed to the fluid system to provide transmission of a mechanical force between these partitioned environments to indicate the fluid pressure. This exterior shape change is such that it can be identified through tactile means not requiring visual identification.

Abstract: A valve body is provided with at one end with a threaded shank for hermetic coupling to a gas container. The valve body is further provided with a handwheel incorporating a gas status indicator device. That device includes a spring-loaded plunger having a head and a helical stem that is engaged in a cavity of a rotatable body so that an axial movement of the plunger, in opposition to a spring biasing force, results in a rotation of the rotatable body. A visible portion of the rotatable body is marked so as to provide an indication of the axial position of the plunger relative to the handwheel, to thereby indicate gas pressure.

Abstract: The invention involves a pressure fault device for indicating a threshold pressure or a threshold differential pressure. The present invention provides a cost effective way to determine where a pressure problem has occurred. The device includes a housing having at least one inlet aperture and an indicator aperture and having first and second bores in fluid communication respectively with one inlet aperture and the indicator aperture. The device further includes a magnetic piston which is biased in the first bore toward one inlet aperture and moveable a predetermined distance in another direction in the first bore in response to inlet threshold pressure. The device further includes a magnetic responder which is moveable toward the indicator aperture in the second bore in response to movement of the magnetic piston. The device further includes a latching plate in magnetic relationship to the magnetic responder when the piston moves the predetermined distance.

Abstract: A hydraulic pressure sensor for measuring the pressure in a hydraulic pressure chamber 1. A reservoir housing 9 is connected to the pressure chamber, and the interior of the housing is divided by a slideable partition 13 which defines a reservoir chamber 8 which is connected to the pressure chamber and a sensor chamber 7 which is connected to a sensor element 5. The partition 13 is constructed as a piston and extends for sliding movement along the walls of the reservoir housing while exerting a frictional force. A spring 11 supports the partition relative to the reservoir housing against the pressure in the reservoir chamber 8. The partition 13 may be constructed as a differential piston, and consist of two or more piston sections 13.1, 13.2, 13.3, which extend independently of one another in a sliding and sealing manner, and mutually support one another by an intermediate spring 14.

Abstract: A device and procedure for checking the health of a pressure transducer in situ is provided. The procedure includes measuring a fixed change in pressure above ambient pressure and a fixed change in pressure below ambient pressure. This is done by first sealing an enclosed volume around the transducer with a valve. A piston inside the sealed volume is then driven forward, compressing the enclosed gas, thereby increasing the pressure. A fixed pressure below ambient pressure is obtained by opening the valve, driving the piston forward, sealing the valve, and then retracting the piston. The output of the pressure transducer is recorded for both the overpressuring and the underpressuring. By comparing this data with data taken during a preoperative calibration, the health of the transducer is determined from the linearity, the hysteresis, and the repeatability of its output. The further addition of a thermometer allows constant offset error in the transducer output to be determined.

Abstract: A device for accurately measuring the pressure (Pg) of very highly pressurized gas includes a cylinder (16) having a cylindrical outer surface (16A) and a bore extending through the cylinder and an elongated piston (23) rotatable and vertically movable in the bore, and supporting calibration weights by means of the piston. An internal reservoir (32) is formed by providing a housing (31) to support the cylinder, the housing including a lower portion engaging a bottom portion of the cylinder and a lower peripheral portion of the cylinder and an upper portion engaging an upper peripheral portion of the cylinder, an inner portion of the housing (31) and a portion of the outer surface (16A). An interior of the reservoir (32) is pressurized through a passage (30A) extending from the reservoir to pressurize gas inlet. A passage (34) conducts pressurized oil from the reservoir into a gap between the piston (23) and the bore.

Abstract: A pressure gauge having a pressure operated piston for measuring the difference in pressure between two pressure signals including an automatically operative pressure relief valve and a manually operable three-way valve to provide a venting function useful for inspecting the operation of the pressure operated piston of the pressure gauge.

Abstract: A test assembly includes a valve and a piston received in a casing. The valve includes a main passage and a flexible seal film is mounted to an end of the valve. The seal film seals the main passage and has two apertures. A radial passage is defined through the valve and communicates with the main passage. A sub-passage is located in parallel with the main passage and communicates with the radial passage and one of the apertures of the seal film. A control member is rotatably and radially inserted in the valve and has a first path radially through the shank of the control member and communicates with the main passage. A second path is defined in half way of the shank and communicates with the first passage.

Abstract: A resistance welding apparatus comprises a piston having opposing faces for applying welding electrodes to a workpiece, means for measuring a pressure ratio across opposing faces of the piston and means for controlling the supply of welding current to the electrodes in dependence on the pressure ratio. A method of resistance welding and a pressure sensor for use in the resistance welding apparatus are also provided.

Abstract: A device for accurately measuring the pressure (Pg) of very highly pressurized gas includes a cylinder (16) having a cylindrical outer surface (16A) and a bore extending through the cylinder and an elongated piston (23) rotatable and vertically movable in the bore, and supporting calibration weights by means of the piston. An internal reservoir (32) is formed by providing a housing (31) to support the cylinder, the housing including a lower portion engaging a bottom portion of the cylinder and a lower peripheral portion of the cylinder and an upper portion engaging an upper peripheral portion of the cylinder, an inner portion of the housing (31) and a portion of the outer surface (16A). An interior of the reservoir (32) is pressurized through a passage (30A) extending from the reservoir to pressurize gas inlet. A passage (34) conducts pressurized oil from the reservoir into a gap between the piston (23) and the bore.

Abstract: The novel sensor assembly is comprised of a threaded housing with pressure relief tracks through the threads that terminate at a hole through the housing and a displacement sensor. In the preferred embodiment, we have included an integral connector, a super-elastic core carrier and a Differential Variable Reluctance Transducer. Other sensor types could be used to construct a pressure equalized displacement sensor as described herein, these may include: capacitive, resistive, Hall effect, eddy current, and differential variable transformer.

Abstract: A pressure regulator utilizing a gauge having rugged internal components. In one embodiment, the gauge has a low profile and is mounted to the regulator body. In another embodiment, the gauge is integral with the regulator body. In one preferred embodiment, the gauge includes a pressure pin and a bias, such as a spring. One side of the pressure pin communicates directly with the source pressure and is urged by the source pressure to move the pressure pin in a first direction, while the other side of the pressure pin is at a known pressure, such as ambient or atmospheric pressure, and is urged by the bias to move the pressure pin in a second direction opposed to the first direction. An indication of the position of the pressure pin is sensed by a user and is used to determine the source pressure or level. In one aspect, the indicator is a pointer or indicator mounted to move in response to movement of the pressure pin and mounted so that its position is visible (i.e., sensed by sight) to the user.

Abstract: A force sensor for sensing the weight of a vehicle seat occupant for a vehicle's occupant protection system has a pressure sensor responsive to hydraulic pressure resulting from axial force applied to the force sensor. A constant force spring in the form of a diaphragm with two flanges simultaneous functions as a seal, a constant force bias spring, an armature support resistant to radial forces and a piston for converting force to hydraulic pressure. Two studs receive applied force. An electrical insulator is sealed to the walls of a passage inside of one of the studs to provide electrical communication while sealing against liquid leakage. A pressure sensor is mounted on the electrical insulator and connected to electrical conductors in the insulator by stitch bonding. The diaphragm resists radial movement while allowing axial movement thereby making the sensor insensitive to radial forces. By being a constant force spring the diaphragm makes the sensor insensitive to temperature variations.

Abstract: The pressure test gauge assembly is a metal valve body interchangeably connected to one of a set of three transparent color coded gauge bodies, each gauge assembly being protected by a color coded transparent sheath when not in use.

Abstract: A hydraulic system for supplying hydraulic fluid for operating a mud pulse generator includes an accumulator that has a reservoir. The accumulator is arranged to maintain the fluid pressure in the reservoir. The system also has a pressure operated, one way inlet valve that is arranged to allow hydraulic fluid to be added, under pressure, to the reservoir. The one way inlet valve also includes a valve core.

Abstract: A pressure gauge has a base which is provided with a slot, and a sliding block located in the slot such that the sliding block is pushed to displace by a piston rod which is in turn pushed by the air pressure to be measured. The sliding block is provided with a plurality of teeth for actuating a rotary shaft and a hand fastened at one end thereof with the rotary shaft. The hand is actuated to turn to point at an air pressure reading. The base is provided with a threaded hole, an adjusting screw engaged with the threaded hole, and a spring which is engaged at one end thereof with the sliding block and at other end thereof with the adjusting screw. The pressure gauge is calibrated by adjusting the position of the adjusting screw in the threaded hole.

Abstract: The pressure gauge is designed for operative engagement with a fluid pressurized system such as a gas or a liquid. It includes a housing having a pressurized fluid inlet orifice and a cylindrical bore formed within the housing. A pressure reactive piston is slidably engaged within the cylindrical bore, and a resistance means is disposed within the cylinder to provide a resistive force to the movement of the piston. A calibration means engages the resistance means to apply a user selectable calibration force to the piston, and a calibration means engagement means is utilized to fixedly engage the calibration means in the user selectable position. An arm member is disposed proximate the piston, whereby movement of the piston will cause movement of the arm member, and a pressure indicator means is engaged to the arm to provide an indication of the pressure level of the fluid.

Abstract: An indicator mechanism symbolizing an operating condition of a valve. The indicator includes a body member attached to the valve and having a window opening. A guide is positioned in the body member to be visible through the window opening. A flower is also disposed within the body member and is movable between a first position retracted from and exposing the guide in the window opening, and a second position extending over and obscuring the guide from the window opening. The flower may be moved by a pressurized fluid acting directly or indirectly on the flower or by mechanical contact with another moving component such as a valve spool.

Abstract: A pressure gauge for a pressurized device is disclosed that provides a simple, efficient and highly visual indication of pressure change from a normal condition to various abnormal conditions. The pressure gauge includes a chamber, a pressure converter located within or operably associated with the chamber, a rotary member coupled to the converter and having an indicator pattern and a cap including at least one window through which at least a portion of the indicator pattern is viewable. Once the gauge is brought into fluid communication with a pressurized device, then the cap may be rotated or adjusted to align the windows with a desired marker type placing the gauge in a normal or first indicator data. A change in pressure in the chamber will cause the gauge to undergo a change to a new or different indicator state.

Abstract: A differential pressure indicator has a piston across which inlet and outlet pressures are applied with a spring preventing movement of the piston until a predetermined differential pressure is exceeded. At this point, a port is opened to allow the inlet pressure to be applied to an indicator button to move the indicator button from a retracted position to an operative extended position to indicate that the pressure differential has been exceeded. The use of fluid pressure to operate the indicator button applies a large force to the indicator button and allows it to be securely held in the inoperative position to guard against accidental movement by high G-forces.

Abstract: An efficiency indicator for a separation system, such as a water filter, wherein a first volume of fluid is exposed, under a first pressure, to a separation medium and a second volume of fluid is recovered therefrom, under a second, lesser pressure. The indicator comprises a housing including an aperture and a biased piston rod in a tube driven between a first position and a second spaced-apart position by the differential between said first and second pressures when said second pressure represents an undesired loss of medium separating efficiency. The piston rod has a first reflective colored coating at one location on said rod and a second reflective colored coating at a second location. A sphere of optical transparent material is mounted so as to project through the aperture of the housing.

Abstract: The present invention provides pressure measuring devices comprising a sensor to detect the force upon at least a portion of a contact surface of a syringe plunger during pressurization of a fluid medium within the syringe. A determination of the pressure of the fluid medium within the syringe is thereby enabled.

Abstract: A compression stroke indicator including an indication mechanism adapted to signal a user upon the application of pressure thereto. Further provided is an elongated elastomeric hose connected at a first end thereof to the indication mechanism. Also included is at least one hollow hose fittings having a first end connected to a second end of the elastomeric hose. Each hollow hose fitting further has threaded grooves formed in a second end thereof for allowing the screwable coupling of a second end thereof to a spark plug aperture of a combustion engine. Upon a pressure being applied to the hose by the engine, the indication mechanism signals a user.

Abstract: The invention relates to an indicator device 1, especially for use as a manometer, with a housing 2 provided with an inlet for the pressurized medium to be measured and a spring-loaded piston 13 which can come into contact with the pressurized medium. The precision of the pressures indicated can be increased and the size can be made especially compact when the piston is designed as a control piston 13 and is in a working connection with an indicator element 5 via a groove and projection combination 39, 40 which translates the stroke of the control piston 13 into a rotating movement of the indicator element 5.

Abstract: A pressure gauge reset mechanism including a cylinder having a pressure measuring head at one end, a piston forced by a first spring toward the pressure measuring head, a toothed pressure rod extending out of the cylinder, an actuating rod member having one end stopped at the piston and an opposite end fixedly connected to the toothed pressure rod, a second spring fixedly connected to the actuating rod member to push it upwards against the piston, and a pressure gauge coupled to the cylinder, the pressure gauge having an index shaft with a gear meshed with the toothed pressure rod, and a torsional spring mounted on the inside to hold down the index shaft and having one end stopped at the inside of the pressure gauge and an opposite end extending out of the pressure gauge and fixedly connected with a button, wherein the second spring member is compressed and the index shaft is turned by the toothed pressure rod to move the index of the pressure gauge when the piston is forced by the pressure being applied to t

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 manometer for use in a patient's breathing circuit, comprising a housing forming a bore and a slider movably mounted within the bore. The slider is movable between an at-rest position, an expanded pressure range, and a contracted pressure range. A spring is connected to the slider for urging the slider toward the at-rest position, while allowing movement of the slider in the two ranges due the pressure in the breathing circuit. The housing is connectable to the breathing circuit such that the gas pressure moves the slider from the at rest position and into at least the expanded pressure range. At relatively low pressures, the slider is moved into the expanded pressure range and at higher pressures, the slider is moved into the contracted pressure range against the force of the spring. The spring is formed by a relatively short tension spring and a relatively long tension spring.

Abstract: A differential pressure control switch system for use in determining the relative position of a piston in a pneumatic cylinder in relation to a pre-set threshold pressure sensing by the differential in the supply side and exhaust side of a double acting pneumatic cylinder and a four-way directional control valve associated therewith.

Abstract: A device for determining a pressure of gas in an evacuated chamber including a cylinder positioned in fluid communication with the evacuated chamber with the cylinder forming a compressed gas chamber, a reciprocating piston received within the cylinder and mounted for reciprocal movement therein, a port or valve for providing selective fluid communication between the compressed gas chamber and the evacuated chamber is disclosed. A drive mechanism is provided for reciprocating the piston between a retracted position, where the compressed gas chamber communicates with the evacuated chamber, and an extended position where communication between the compressed gas chamber and the evacuated chamber is interrupted, the position being a position where a pressure transducer determines that a predetermined pressure differential between the chambers has been reached.

Abstract: A tire pressure gauge comprises an outer housing seat provided with a semicircular slot having one open end provided with a ring-shaped edge and having another open end provided with a semicircular arresting edge. A first outer housing cover is used to fix a guide tube. The outer housing seat is provided with a battery compartment and a lamp socket extending from the periphery of the battery compartment toward the outer edge of the outer housing seat. A second outer housing cover is used to fix the batteries and the lighting fixture. The guide tube is provided at the front end thereof with a partition having a protruded column extending outwards from the center thereof. The protruded column is provided in one side thereof with an air hole. Disposed sequentially behind the partition in the guide tube are a piston, a pressure scale, a spring and a plug having a through hole dimensioned to permit the pressure scale to extend therethrough.

Abstract: A torque indicator system for use while rotating a screw pile into the ground with a positive displacement hydraulic motor, includes first and second hydraulic cylinders having their rods connected together in a manner such that net pressure forces are created in response to the high inlet and low outlet pressures of the motor. A pressure gauge mounted on one of the cylinder assemblies reads the working pressure drop across the motor, which is directly related to its output torque.

Abstract: A gauge for detecting the impulse generated in sample materials by X-rays or other impulse producing mechanisms utilizes a pair of flat annular springs to support a plunger relative to a housing which may itself be supported by a pair of flat annular springs in a second housing. The plunger has a mounting plate mounted on one end and at the other, a position or velocity transducer is mounted. The annular springs consist of an outer ring and an inner ring with at least three arcuate members connecting the outer ring with the inner ring.

Abstract: A differential pressure gage apparatus is disclosed which utilizes two pistons movable within three bores to produce accurate differential pressures. An inner piston carried by an outer piston has sufficient length to extend into all bores at once.

Abstract: A tire pressure indicator includes an indicator main body having a first end adapted to be connected to an inflating valve member of a tire and a second end which provides a tire pressure reading. A light device has a rotatable support rotatably mounted on an appropriate location of the indicator main body, a light emitting device provided on the rotatable support, and a switch activated control circuit similarly provided on the rotatable support so as to control the operation of the light emitting device. The light device facilitates the connection of the tire pressure indicator to the inflating valve member of a tire and the viewing of the tire pressure reading under poor lighting conditions.

Abstract: A device for continuously monitoring the difference in pressure of fluid in two closed spaces and separated by a dividing wall comprises an open-ended tubular housing which is secured to a rigid tube passing through and rotatably mounted in a horizontal passage in the wall with their axes inclined at an angle to one another. By rotably adjusting the housing with respect to the wall, the housing can be arranged to lie at a desired angle to the horizontal. The housing has a length three times its internal diameter and is transparent in end parts and opaque in a central part, each part being equal to a third of the total length of the housing. Two balls, each of a diameter slightly less than the internal diameter of the housing, are retained and free to roll within the housing, the ball remote from the wall being green and the other red.

Abstract: A fluid filter clogging display comprising a case of non-magnetic material divided into an upper housing, at atmospheric pressure, and a lower housing by an impermeable membrane, a piston movable in the lower housing and dividing the lower housing into a high chamber and a low chamber, the high chamber communicating with an upstream side of a filter and the lower chamber communicating with a downstream side of the filter, a magnet mounted on the piston and disposed in the high chamber, a magnetizable detector in the upper housing for sensing a position of the magnet, a return spring located in said low chamber biasing the piston towards the impermeable membrane and a helical spring made of a shape memory alloy (SMA) which is stiff above a specific temperature and compliant below such a temperature and mounted such that the SMA spring joins the magnet to the piston depending upon the temperature thereof.

Abstract: The invention device monitors the pressure of a measurement chamber subjected to the pressure prevailing in a vehicle tire. A pressure-sensitive device scans the tire pressure with a pressure measurement member in a measurement chamber. In case of a tire-pressure drop, the tire pressure is used to actuate an auxiliary actuator (3, 24, 26). The auxiliary actuator genrates the regulating distance (s) dependent on a tire pressure drop below a pressure value required for an actuation of the actuator (13). The regulating distance (s) is recognizable by a sensor. The invention device is suitable for providing a permanent signal even in case of an absence of pressure in the measurement chamber (21).

Abstract: A tire monitoring and repairing device comprises a body having a front arm and a rear grip arm interconnected at their upper end with a connecting member to substantially form a U-shape. A pressure gauge is mounted in the front arm and a flash light device is mounted in the rear grip arm. The front arm further has a mouth piece projecting forward to form a pressure inlet. A tire repairing tool is detachably screwed to the mouth piece of the front arm. In addition, a tire tread ruler is provided in the rear grip arm.

Abstract: An air pressure measuring pen of a neat and satisfactory design is provided. The pen includes a transparent hollow pen tube having a top end and a bottom end, a clipping cover connected to the top end and having an exhaust valve, a check valve and a measuring head, a spring urging in the pen tube apart a stopping medium and a piston in the pen tube, an ink holder, and an ink holder positioner connected to the bottom end.

Abstract: A pressure gauge has a device which can be pre-arranged to indicate the required pressure in a connected tire, and releases the excessive pressure if there should by any.

Abstract: A measuring head for an air pressure gauge having a movable actuating rod and capable of obtaining the car power source from the cigarette lighting socket is provided. The measuring head includes an insulating head tube having a through hole, a conductible actuating rod having an intermediate annual flange and an upper portion protruding beyond the through hole, a conductible plug having an axial through hole, a spring mounted between the plug and the annular flange for tightly urging the flange against the tube, and a conductible sleeve sleeved on the tube and connecting thereto a conducting wire.

Abstract: An improved closed-end manometer which overcomes the problems associated with prior U-tube manometer devices. The invention comprises a small bore tube which is transparent or translucent at least along the measuring portion and which may be of tapered or cylindrical bore, a permanent closure at one end of the tube, a relatively small indicating slug formed of a suitable liquid, a measuring scale to note the position of the liquid slug, and a measured quantity of a selected gas between the closure and the nearest end of the liquid slug. The open end of the tube is connected to the vessel or system whose pressure is to be measured or monitored. One feature of the present invention is its ability to provide quantitative pressure indications over a wide range of pressures, or the invention may be calibrated to provide increased sensitivity over a relatively short measuring range. Another feature of the invention is its ability to provide accurate pressure measurements regardless of the instrument's orientation.