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Showing papers on "Pressure measurement published in 1977"


Journal ArticleDOI
TL;DR: It is shown that the resonant frequency observed in these spectra will vary as the cardiac pressure changes, so the variations of the resonance can be calibrated to give the pressure excursions in a cardiac chamber.
Abstract: We suggest and analyze a new technique for making non-invasive cardiac measurements. The technique involves measurement of the spectrum of ultrasound scattered from small bubbles injected into the circulatory system as they pass through the heart. We show that the resonant frequency observed in these spectra will vary as the cardiac pressure changes. Thus the variations of the resonance can be calibrated to give the pressure excursions in a cardiac chamber. Preliminary bench tests of the method are described which show the predicted shift with pressure of the resonance frequency of bubbles in water.

95 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of membrane penetration in undrained tests was shown to reduce the rate of change in pore pressure; and the effective stresspath, stress-strain relations, and undrained strength were modified accordingly.
Abstract: It was found that membrane flexibility can change the soil behavior and pore pressure characteristics far more than may be caused by, e.g., the flexibility of the pore pressure measuring system. Expressions were developed for the pore pressure parameters, B and A, which include the effects of flexibilities of membrane and pore pressure measuring system. Measured and calculated B-values agreed well for saturated specimens in which membrane penetration could occur. The effects of time and partial saturation on the measured B-values were also studied. The effect of membrane penetration in undrained tests was to reduce the rate of change in pore pressure; and the effective stress-path, stress-strain relations, and undrained strength were modified accordingly. The strengths obtained from cyclic loading tests performed on saturated specimens of granular materials for determination of liquefaction potential were also shown to be affected by membrane penetration.

91 citations


Journal ArticleDOI
TL;DR: It is shown that a wide cuff does effectively accomplish this under its central region and the claim that ‘if the cuff is too wide, the reading will be erroneously low’ is not indicated in the analytical solution and has not been observed in the authors' experiments.
Abstract: For a sphygmomanometric method of indirect blood-pressure measurement to be accurate, the cuff must operate so that the intrabladder pressure is always the same as the pressure applied by the tissues of the arm to the artery wall. To determine under what conditions this occurs, analyses are presented assuming the arm to be a rotationally symmetric, incompressible solid cylinder acted upon by various cuff pressure fields. The results indicate that the pressure applied to the artery wall is markedly influenced by longitudinal motion of the arm tissue, which must be constrained to have an accurate pressure transmission. It is shown that a wide cuff does effectively accomplish this under its central region. The analyses agree with experiments in which indirect and direct blood-pressure measurements were made and most of the clinical observations of others. However, the claim that ‘if the cuff is too wide, the reading will be erroneously low’ is not indicated in the analytical solution and has not been observed in the authors' experiments. These analytical and experimental results were used to establish criteria for the design of appropriate occluding cuffs. Based upon these criteria, cuffs for clinical use have been produced from a plastic film in a variety of lengths and widths.

71 citations


Journal ArticleDOI
TL;DR: In this paper, the molar volume V and ultrasonic velocity u of fluid n-H2 were measured simultaneously in a piston-cylinder apparatus over the range 75
Abstract: The molar volume V and ultrasonic velocity u of fluid n–H2 were measured simultaneously in a piston–cylinder apparatus over the range 75

53 citations


Proceedings ArticleDOI
05 Oct 1977
TL;DR: In this article, coherence measurements between fluctuating pressure in the combustor of a YF-102 turbofan engine and far-field acoustic pressure were made, and the results indicated that a coherent relationship between combustor pressure and far field acoustic pressure existed only at frequencies below 250 Hz, with the peak occurring near 125 Hz.
Abstract: Coherence measurements between fluctuating pressure in the combustor of a YF-102 turbofan engine and far-field acoustic pressure were made. The results indicated that a coherent relationship between the combustor pressure and far-field existed only at frequencies below 250 Hz, with the peak occurring near 125 Hz. The coherence functions and the far-field spectra were used to compute the combustor-associated far-field noise in terms of spectra, directivity, and acoustic power, over a range of engine operating conditions. The acoustic results so measured were compared with results obtained by conventional methods, as well as with various semiempirical predictions schemes. Examination of the directivity patterns indicated a peak in the combustion noise near 120 deg (relative to the inlet axis).

33 citations


Journal ArticleDOI
TL;DR: In this paper, the development of the flow fields generated by firing a 7.62-mm caliber rifle was measured using a time-resolved spark shadograph technique, and the local and temporal pressure distribution in the muzzle blast field of the rifle was determined by immersing quartz probes in the flow.

25 citations


Patent
04 Aug 1977
TL;DR: In this paper, an actuator valve and a relief valve are used to detect when the hose is clogged and bleeds in cooling air to prevent overheating of the motor blower.
Abstract: A vacuum cleaner detector that indicates when the hose is clogged and bleeds in cooling air to the vacuum chamber so as to prevent overheating of the motor blower. The indicator comprises an actuator valve and a relief valve. The actuator valve includes a pressure responsive member having filter bag compartment pressure applied to one side thereof and atmospheric pressure applied to the other side. When the absolute pressure within the filter bag chamber drops, the pressure responsive member is moved toward the low pressure side moving a plunger which opens a port when the pressure drops below that desired to allow filter bag chamber pressure to vent to the low pressure side of a pressure responsive member in the relief valve. The other side of the relief valve pressure responsive member is acted upon by atmospheric pressure which thereby forces the pressure responsive member away from a bleed hole to allow atmospheric pressure to flow into the filter bag chamber to insure that the motor blower has sufficient air flow for cooling, and simultaneously the pressure responsive member forces an indicator button out of the cleaner. Also disclosed is a vacuum cleaner filter bag condition indicator that detects when the bag is substantially full and should be replaced. The use of the two indicators together allows the determination of whether the filter bag is full or whether the hose is clogged.

24 citations


01 Sep 1977
TL;DR: In this paper, the authors used correlation and coherence techniques to determine the relative phase and amplitude relationships between the internal pressures and far field acoustic pressure in a turbofan engine and found that the combustor is a low frequency source region for acoustic propagation through the tailpipe and out to the far field.
Abstract: Fluctuating pressure measurements within the combustor and tailpipe of a turbofan engine are made simultaneously with far field acoustic measurements. The pressure measurements within the engine are accomplished with cooled semi-infinite waveguide probes utilizing conventional condenser microphones as the transducers. The measurements are taken over a broad range of engine operating conditions and for 16 far field microphone positions between 10 deg and 160 deg relative to the engine inlet axis. Correlation and coherence techniques are used to determine the relative phase and amplitude relationships between the internal pressures and far field acoustic pressures. The results indicate that the combustor is a low frequency source region for acoustic propagation through the tailpipe and out to the far field. Specifically, it is found that the relation between source pressure and the resulting sound pressure involves a 180 deg phase shift. The latter result is obtained by Fourier transforming the cross correlation function between the source pressure and acoustic pressure after removing the propagation delay time. Further, it is found that the transfer function between the source pressure and acoustic pressure has a magnitude approximately proportional to frequency squared. These results are shown to be consistent with a model using a modified source term in Lighthill's turbulence stress tensor, wherein the fluctuating Reynolds stresses are replaced with the pressure fluctuations due to fluctuating entropy.

14 citations


Journal ArticleDOI
TL;DR: In this article, the surface pressures directly behind a Laser-Supported Detonation (LSD) were measured with a system of carbon piezoresistive gauges and a quartz piezoelectric gauge was also used to measure surface pressures far away from the laser spot.
Abstract: The surface pressures directly behind a Laser‐Supported Detonation (LSD) were measured with a system of carbon piezoresistive gauges. A quartz piezoelectric gauge was also used to measure surface pressures far away from the laser spot. The small size of the carbon gauges, relative to the laser beam diameter, permitted simultaneous resolution of the surface pressure history at several locations within the laser spot. A comparison of the experimental data with recent theories indicates that the theories predict peak pressures close to those measured but overestimate the impulse intensity at the target surface.

14 citations


Patent
28 Jun 1977
TL;DR: A fluid pressure transducer has a sealed capsule with a thin bellows wall of flexible plastics material and rigid end walls attached to a support and to an indicator respectively, so that longitudinal expansion and contraction of the capsule due to variation of the pressure of the fluid in which the capsule is immersed give an indication of this pressure as discussed by the authors.
Abstract: A fluid pressure transducer has a sealed capsule with a thin bellows wall of flexible plastics material and rigid end walls attached to a support and to an indicator respectively, so that longitudinal expansion and contraction of the capsule due to variation of the pressure of the fluid in which the capsule is immersed give an indication of this pressure. The capsule contains a gas which imparts an effective elasticity to the capsule, the elasticity of the bellows wall itself being negligible, so that the length of the capsule is to a close approximation inversely proportional to the applied pressure. For direct pressure measurement the floating end of the capsule may carry an indicator which is visible through a wall of a rigid capsule-enclosing casing to which the pressure to be measured is applied. An instrument for use as a depth gauge may incorporate the transducer, which for this application may include a calibrated flow restrictor through which fluid pressure is applied to the capsule, such that the consequent delay in the depth reading provided by the transducer indicates to a diver the length of successive decompression stops during an ascent from depth.

13 citations


Patent
19 Dec 1977
TL;DR: In this article, the internal volume of an object is measured by measuring the pressure and temperature changes when a container of known pressure and volume is attached to the object being measured, according to the specified formula.
Abstract: PURPOSE: To measure the internal volume promptly and easily, by calculating according to the specified formula by detecting the pressure and temperature changes when a container of known pressure and volume is attached to the object being measured. CONSTITUTION: By opening and closing valves 5a, 5c, 5b, a container 1 of known volume V o is decompresses by a vaccum pump 2 or the like. By closing the valve 5b, the pressure and temperature, P 1 , T 1 , of the gas in the container 1 are measured by a pressure gauge 3 and a thermometer 4. Next, by opening the valve 5a, the container 1 is communicated with the object being measured 7 which accommodates a gas at pressure P o and temperature T o . The pressure P 2 and the temperature T 2 after such communicating are similarly measured. Then, according to equation I, the volume V x of the object being measured 7 may be easily measured. Hence, by averaging the measurements taken repeatedly, the volume may be measured at high precision. COPYRIGHT: (C)1979,JPO&Japio

Patent
27 Jan 1977
TL;DR: The piezo-resistive pressure transducer as discussed by the authors consists of an integrated circuit chip formed from N-type Silicon with P-type resistance elements, connected to the resistors via the metallisation layer to gold wires.
Abstract: The piezo-resistive pressure transducer consists of an integrated circuit chip formed from N-type Silicon with P-type resistance elements. Connections to the resistors are made via the metallisation layer to gold wires (19). The underside of the chip is machined away to form a recess (23) so that the wafer becomes a flexible membrane. Mechanical distortion of the resistor elements due to pressure changes will produce a corresponding change in their resistance value. A ceramic back plate (7) is welded to the chip and an isolation layer of anodised ceramic or anodised aluminium separates the cell from a metal base plate (10). All seals for the connectors (12) and central tube (15) are of glass. For use as an absolute pressure transducer, the inner space (23) is evacuated and the tube sealed off.

Patent
25 Mar 1977
TL;DR: In this article, a single pressure transducer tapped into the fuel system of an engine is used to measure fuel pressure at low idle speed and at high idle speed of the engine; the two pressures when compared against normal pressure can determine bypass valve condition.
Abstract: A single pressure transducer tapped into the fuel system of an engine, at a point to be responsive to the pressure of the fuel operating against the pressure regulating bypass valve of the fuel system, is used to measure fuel pressure at low idle speed and at high idle speed of the engine; the two pressures when compared against normal pressure can determine bypass valve condition since lower than normal pressure at low idle speed in combination with normal pressure at high idle speed is an indication of a bypass valve which is stuck in the open position, and higher than normal pressure at high idle speed is indication of a bypass valve which is stuck in the closed position. The test can also discern other faults since a lower than normal pressure at high idle speed in combination with a lower than normal pressure at low idle speed is indicative of a bad pump. And, a normal pressure at low idle speed and a lower than normal pressure at high idle speed together are indicative of a filter or other restriction in the line. An exemplary process for making the fuel pressure measurements at two different speeds and a simple illustration of diagnostic analysis of the results thereof are disclosed. Since excessive high idle pressure resulting from the bypass valve being stuck in the closed position will exceed any normal pressure reduction from line restrictions (usually due to dirty filters), even combined faults can be isolated, one at a time.

Patent
29 Aug 1977
TL;DR: In this paper, a mounting structure carrying a thin, pressure sensitive resistance wire is lodged in a gas passageway extending through an outer member, and the mounting includes a relatively large end portion which extends substantially across the passage to both shield the wire from direct impact by passing gas, and limit the flow of such gas by occluding the passage.
Abstract: Pressure sensing apparatus in which a mounting structure carrying a thin, pressure sensitive resistance wire is lodged in a gas passageway extending through an outer member. The mounting includes a relatively large end portion which extends substantially across the passageway to both shield the wire from direct impact by passing gas, and limit the flow of such gas by occluding the passageway. The secure wire mounting apparatus makes possible the use of very thin wires and a corresponding increase in pressure sensitivity resulting from temperature and gas thermal conductivity. The wire diameter is no more than about 0.00005 inch, making possible results comparable to much more expensive mass spectrometer techniques. An overall pressure sensing system is described in which the sensor is coupled with electric circuitry to produce transient and/or absolute pressure readings over an approximately nine decade pressure range. Transient readings of gas temperature and thermal conductivity may also be made.

Patent
29 Mar 1977
TL;DR: The gas pressure/temperature monitor for gas-quenched electrical switchgear consists of a temperature sensor which monitors the temperature of the quenching medium, e.g. Sulphur Hexachloride as discussed by the authors.
Abstract: The gas pressure/temperature monitor for gas-quenched electrical switchgear consists of a temperature sensor (1) which monitors the temperature of the quenching medium, e.g. Sulphur Hexachloride. The signal is converted to digital form (5) as an address for a read-only-memory (6) in which is stored the density characteristic for the gas. The temperature-related pressure is compared with the actual value of the gas pressure as sensed by a pressure gauge (7). This signal is digitised and fed to an 8-bit comparator (10). If the actual value falls below the desired value, then a relay is energised (11) to operate an alrm. In order to provide an additional signal when the acutal value approaches a critical value, a second comparator is used (12) which is fed from the ROM via an adder (13) whose second input is fed with an additional set point value.

Patent
19 Dec 1977
TL;DR: In this article, a vessel of variable inside volumes is connected to the closed system of unknown inside volume thereby constituting one closed system, and the volume of the measuring object 11 is calcualted based on the respective measurement values.
Abstract: PURPOSE: To improve measurement accuracy by connecting a vessel of variable inside volumes to the closed system of unknown inside volume thereby constituting one closed system. CONSTITUTION: After the measuring object 11 is connected to a connection port 10, cocks 8, 9 are opened and a positive or negative pressure is applied thereto by fixing the position of a piston 2 at the upper or lower limit of a cylinder 1. The pressure P 1 and temperature T 1 of this time are measured with a pressure gauge 6 and thermometer 7. Next, the cocks 8, 9 are closed and the air having been confined in the cylinder 1 is suitably compressed or reduced by a handle 4, after which the piston 2 is fixed in a suitable position by a stopper 5 and the volume V 2 is read with a shaft 3. At the same time, the pressure V 2 and temperature T 2 in the cylinder 1 are measured. Thereafter, the cock 9 is opened and the pressure V 3 , temperature T 3 in the cylinder 1 are measured. The volume of the measuring object 11 is calcualted based on the respective measurement values. COPYRIGHT: (C)1979,JPO&Japio

Patent
17 May 1977
TL;DR: In this article, a combination manifold absolute pressure and ambient absolute pressure sensor is used to provide altitude compensation in a fuel injection system, which is utilized to provide a signal indicative of atmospheric absolute pressure.
Abstract: A combination manifold absolute pressure and ambient absolute pressure sensor utilizing a single absolute pressure sensor and a second sensor which is devised to sense the difference between the manifold pressure and atmospheric pressure. The second sensor is provided with a switch mechanism actuated by a diaphram at a preselected pressure difference between manifold pressure and atmospheric pressure. The actuation of the switch mechanism causes a sample-and-hold circuit to sense the instantaneous manifold absolute pressure at the time of actuation of the switch and electrically add the sensed manifold pressure to the set difference between the manifold pressure and atmospheric pressure to provide a signal indicative of ambient absolute pressure. This signal is utilized to provide altitude compensation in a fuel injection system.

Journal ArticleDOI
Richard J. Driscoll1, L. F. Moon1
TL;DR: In this paper, a one-dimensional flow model of the chemical laser, from combustor to subsonic diffuser, is developed for the study of laser pressure recovery, and the results from experimental tests on a laser nozzle array with a constant area diffuser are presented.
Abstract: A one-dimensiona l flow model of the chemical laser, from combustor to subsonic diffuser, is developed for the study of laser pressure recovery. Combustor and flow chemistry effects, nozzle and cavity boundary-layer losses, laser cavity combustion, and nozzle, cavity, and diffuser geometry influences are included in the analysis. The results from experimental tests on a laser nozzle array with a constant area diffuser are presented. Diffuser exit pressures as high as 263 Torr were measured during these experiments. The one-dimensional flow model is shown to be in agreement with the measured diffuser exit pressures over the full range of test conditions.

Patent
13 Jul 1977
TL;DR: In this article, a combination tire inflator and pressure gauge, having a valving member and a body member having ports and passages with which the valving members co-operates to provide flow or non-flow and selective communication of the pressure source, the gauge, and the tire, depending upon the relative location or setting of the Valving member with respect to the body member.
Abstract: A combination tire inflator and pressure gauge, having a valving member and a body member having ports and passages with which the valving member co-operates to provide flow or non-flow and selective communication of the pressure source, the gauge, and the tire, depending upon the relative location or setting of the valving member with respect to the body member. In three relative positions of the valving member, respectively, it (1) interconnects the gauge and tire passages, the pressure-source passage being blocked, thus showing tire pressure; (2) vents the tire and gauge passages, the pressure-source passage likewise being blocked, thus venting air from the tire; and (3) causes or permits communication of the pressure-source and the tire passage, the gauge passage being blocked, thus inflating the tire.

Patent
02 Dec 1977
TL;DR: In this article, a method and apparatus for determining the upper dead center position in piston engines is presented, in which the crankshaft angle corresponding to the maximum compression pressure is determined by a pressure measurement and by the addition of a correcting factor that corresponds to the thermodynamic loss angle conditioned by heat transfer and leakage losses.
Abstract: A method and apparatus for determining the upper dead-center position in piston engines, in which the crankshaft angle corresponding to the maximum compression pressure is determined by a pressure measurement and by the addition of a correcting factor that corresponds to the thermodynamic loss angle conditioned by heat-transfer and leakage losses.

Journal ArticleDOI
01 Jan 1977-Vacuum
TL;DR: In this paper, a compact stainless-steel ultra-high vacuum system is designed, constructed and tested which enables any vacuum gauge to be calibrated absolutely, quickly and reliably over the pressure range 10 torr to 10 −8 torr.

Journal ArticleDOI
TL;DR: In this article, a simple system for measuring slurry concentrations and flow rates by pressure difference devices has been studied, where the venturi performance has been described in terms of a discharge coefficient based on mixture density, and the concentration measurements were compared to values determined by weigh tank samples.

Patent
29 Jun 1977
TL;DR: In this paper, a pivotal arm is adapted to define a cylinder, a piston and a chamber filled with an incompressible fluid, which is connected to a pressure gauge which displays information representing the pressure prevailing in the chamber, which pressure is proportional to the load suspended from the hook.
Abstract: The hoisting device has means for weighing the load and is particularly compact, simple and reliable. For this purpose a pivotal arm to which a hook is connected is adapted in such manner as to define a cylinder, a piston and a chamber filled with an incompressible fluid. This chamber is connected to a pressure gauge which displays information representing the pressure prevailing in the chamber, which pressure is proportional to the load suspended from the hook.

Patent
18 Jul 1977
TL;DR: In this article, a pressure-applying device such as a cuff was used to measure the shape, amplitude and frequency of the pulse, for monitoring variations in arterial pressure and for measuring and indicating digitally systolic, mean and diastolic pressures.
Abstract: The invention relates to an apparatus and a process for measuring circulatory parameters by external route The apparatus of the invention consists of a pressure-applying device such as a cuff 1 to which is connected a Y-shaped tube 2 of which one of the branches 2a is connected to one pole 3a of an electronic differential pressure gauge 3, in itself already known, and the other branch 2b is connected to an airtight air-reservoir 4, there being situated on the said other branch between the air-reservoir and the pressure-applying device a device 5 for closing the said other branch together with the outlet 6 of an air-pump 7, the outlet of the said air-reservoir being connected to the other pole 3b of the differential pressure gauge The invention may be used for determining the shape, amplitude and frequency of the pulse, for monitoring variations in arterial pressure and for measuring and indicating digitally systolic, mean and diastolic pressures

Journal ArticleDOI
TL;DR: In this article, it was shown that when a gas-operated free-piston pressure gauge is used for measuring pressure relative to atmospheric pressure, the usual relative rotation of the piston and cylinder with added masses can produce a pressure effect up to ten times greater than the accuracy of measurements relative to vacuum.
Abstract: It is shown that when a gas-operated free-piston pressure gauge is used for measuring pressure relative to atmospheric pressure, the usual relative rotation of the piston and cylinder with added masses can produce a pressure effect up to ten times greater than the accuracy of measurements relative to vacuum. The magnitude of this pressure effect depends on the rotational frequency and on whether a bell-jar is in place or not.

Patent
09 Feb 1977
TL;DR: In this article, an apparatus for automatically controlling tunnel face hydraulic pressure in a hydraulic chamber defined by a rotary cutter head and bulkhead in a shield type excavator used in hydraulic tunnel boring system is presented.
Abstract: An apparatus for automatically controlling tunnel face hydraulic pressure in a hydraulic chamber defined by a rotary cutter head and bulkhead in a shield type excavator used in hydraulic tunnel boring system including a pipe for feeding a hydraulic material with a feeding pump from a reservoir to the chamber and a pipe for discharging a mixture of the fed hydraulic material with ground formations excavated by the cutter head from the chamber to the reservoir with a discharging pump. The apparatus substantially comprises a first pressure gauge for measuring actual tunnel face hydraulic pressure in the chamber, a feeding-pipe bypass provided close to the chamber, a first pressure regulating valve provided in the bypass, a second pressure regulating valve in the feeding pipe bypassed by the bypass, a first pressure regulator in which a first predetermined feeding pressure is preset for comparing the actual pressure measured by the first gauge with the first predetermined feeding pressure and controlling the second valve responsive to any differences between the both pressures compared in the first regulator, a second pressure gauge for measuring fed-hydraulic-material pressure upstream the bypass a third pressure regulating valve provided in the feeding pipe upstream the second pressure gauge, and a second pressure regulator in which a second predetermined feeding pressure is preset for comparing the measured fed-hydraulic-material pressure with the second predetermined pressure and controlling the third valve responsive to any differences between the both pressures compared in the second regulator. The second predetermined feeding pressure is preferrably made slightly higher than the first predetermined feeding pressure.

T H Moulden, J M Wu, F G Collins, H J Ramm, H Kuwand 
01 Jun 1977
TL;DR: In this article, the measurement error in a pressure orifice of diameter of the same order as the boundary layer thickness was evaluated and the disturbance created in the flow downstream of the orifice was investigated.
Abstract: : Experiments have been performed to evaluate the measurement error in a pressure orifice of diameter of the same order as the boundary layer thickness, and to investigate the disturbance created in the flow downstream of the orifice. It is shown that for small orifice depths the downstream disturbance is small but the flow in the orifice is quite strong. For larger orifice depths the downstream disturbance increases and the measurement error tends to a constant value.

Patent
02 Mar 1977
TL;DR: In this paper, the authors proposed a system based on what is commonly known as the Villari effect which is the dependence of the magnetic permeability of certain magnetic materials upon applied stress, and permits pressure measurements to be made without any mechanical or physical penetration of the fuel cladding or end cap of a fuel rod.
Abstract: A system including a sensor and electronic instrumentation for measuring fission gas pressures inside a pressurized system or device or the like, such as a nuclear fuel rod. The system is based primarily on what is commonly known as the Villari effect which is the dependence of the magnetic permeability of certain magnetic materials upon applied stress, and permits pressure measurements to be made without any mechanical or physical penetration of the fuel cladding or end cap of the fuel rod. In a preferred embodiment pressure sensing is implemented by locating a sensor made from Villari sensitive material inside the pressurized system. The pressure places a stress loading on the sensor which in turn produces electrical output signals proportional to the applied stress. By sensing the initial magnetic permeability of the sensor, the difference between that sensed information and subsequently sensed similar information can be obtained, thereby providing an indication of any change in system pressure and the degree of such change. Such measurements can be made sequentially at multiple locations by placing an external electromagnetic search coil adjacent the internal sensor in the pressurized system such that the magnetic field of the search coil penetrates the containment wall of the pressurized system, thus interrogating the sensor and providing an appropriate readout which can be calibrated in terms of system pressure.

Journal ArticleDOI
TL;DR: In this article, a gold-chromium (1.95±0.05% Cr) alloy pressure gauge, optimized to get the best metrological properties, was used for measurements of high pressures up to about 20,000 bars.
Abstract: This paper discusses the technological processing of the gold–chromium (with 1.95±0.05% Cr) alloy pressure gauge, optimized to get the best metrological properties. It also presents experimental results of thermal and pressure measurements of the alloy. It was found that the Au–Cr pressure gauge, properly seasoned in the controlled seasoning process, is completely free of hysteresis in resistance due to pressure changes, with uncertainty of less than 0.4 bar in 6000 bars range. Resistance‐pressure and resistance‐temperature characteristics didn’t change during the pressure or temperature cycling. It is also shown in the paper that there is a possibility of employing Au–Cr pressure gauges for measurements of high pressures up to about 20 000 bars.

Patent
15 Dec 1977