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Showing papers on "Pressure measurement published in 1971"


Journal ArticleDOI
TL;DR: In this article, an attempt is made to compare pressure calibration methods among several laboratories in an unbiased way to produce some indication of the bandwidth of observations on the pressure of an equilibrium reaction where sources of discrepancy not resulting from pressure calibration are likely to have been eliminated.
Abstract: An attempt is made to compare pressure calibration methods among several laboratories in an unbiased way to produce some indication of the bandwidth of observations on the pressure of an equilibrium reaction where sources of discrepancy not resulting from pressure calibration are likely to have been eliminated. The reaction chosen is the breakdown of albite to jadeite and quartz under pressure.

229 citations


Journal ArticleDOI
TL;DR: In this paper, the melting temperatures of gold, silver, and copper as a function of pressure have been determined to 65 kb by differential thermal analysis and the precision of the results is high.
Abstract: The melting temperatures of gold, silver, and copper as a function of pressure have been determined to 65 kb by differential thermal analysis. The precision of the results is high. Replicate determinations at a given pressure agree within ±2°. After application of appropriate corrections for the effect of pressure on the emf of thermocouples, the melting curves are linear with the isothermal volume of the melting solid to within the precision of the measurement. Good agreement exists between shock-wave data, ultrasonic data, and static measurements on the relationship between P and V for these metals. Thus by extrapolation of the linear melting relationship, it is possible to construct a melting curve for these three metals to 200 or more kb. We propose the melting curve of gold as a primary standard of pressure measurement for work at high temperatures and pressures in the region 100–200 kb over the temperature interval 1600–2000°C.

130 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured the film shape, pressure and temperature profiles in a disk machine under conditions of elastohydrodynamic lubrication and found that the sharp peaks of pressure near the outlet which are predicted in the theory are in practice considerably attenuated but do occur in the correct positions.
Abstract: The film shape, pressure and temperature profiles have been measured in a disk machine under conditions of elastohydrodynamic lubrication. They were obtained with a new design of transducer which enables the various measurements to be accurately inter-related. In the case of the film shape and pressure measurements the corresponding theoretical solutions have been calculated and detailed comparison made. It has been shown that the sharp peaks of pressure near the outlet which are predicted in the theory are in practice considerably attenuated but do occur in the correct positions. The associated dip in film thickness is also much reduced. Johnson’s recent postulate that the position of the pressure spike should be a function of a single parameter has been examined and found to hold for this new range of experimental data.

66 citations


Journal ArticleDOI
TL;DR: In this paper, the melting temperature is measured with a platinum resistance thermometer mounted on the vessel, while the corresponding melting pressure is measured using a high-precision manganin resistance pressure gauge, which is connected to the pressure system.
Abstract: Techniques for the precise measurement of the P–T melting curves of gases at pressures up to about 12 kbar have been developed. In the method used, a pressure vessel is maintained at a temperature constant to within ± 0.002°K. The pressure in the system is adjusted by manipulation of the pressure generating intensifier until solid–fluid coexistence is obtained within the vessel. The melting temperature is then measured with a platinum resistance thermometer mounted on the vessel, while the corresponding melting pressure is measured with a high‐precision manganin resistance pressure gauge, which is connected to the pressure system. This method has been employed in making extensive P–T melting curve measurements in argon at pressures ranging from 0.58–11.41 kbar and temperatures from 97.8–272.9°K. The estimated precision in the results is ± 0.4 bar in pressure and ± 0.002°K in temperature. The absolute accuracy of the measurements, especially pressure, may be somewhat less due to uncertainty in the defining...

60 citations


Journal ArticleDOI
TL;DR: In this article, the Mie-Gruneisen equation of state of the pressure as a function of temperature along the isochores of helium up to 20 kbar (1 kbar = 108 N m−2) was calculated.

53 citations


Patent
06 Aug 1971
TL;DR: In this article, a submersible electric motor driven pump having a motor chamber and a pump chamber separated by a seal chamber is described. And the switch is connected in circuit with the power controls to the motor and is held closed by a predetermined minimum pressure of gas.
Abstract: A submersible electric motor driven pump having a motor chamber and a pump chamber separated by a seal chamber. A shaft seal is immersed in oil in the seal chamber and prevents the flow of liquid from the pump chamber into the motor chamber. The motor chamber is filled with gas under pressure which aids in sealing it. The gas is introduced to a pressure operated switch and a pressure gauge, which may be located above the surface of the liquid in which the pump is submerged. The pressure operated switch is connected in circuit with the power controls to the motor and is held closed by a predetermined minimum pressure of gas in the motor chamber. In case of a pressure loss from a shaft seal failure the switch is automatically opened and power to the motor is interrupted thus preventing pumped liquid from entering the motor chamber while the motor is energized.

40 citations



Patent
23 Aug 1971
TL;DR: In this article, a method and system for determining the magnitude of a driving force being exerted on a substantially rigid object being driven into the earth, such as a pile, and controlling the magnitude in response to that determination is presented.
Abstract: A method and system for determining the magnitude of a driving force being exerted on a substantially rigid object being driven into the earth, such as a pile, and controlling the magnitude in response to that determination. Where the pile driver utilizes a massive piston weight reciprocating in a cylinder and bouncing upon pressurized fluid in a chamber, the force magnitude is determinable by sensing pressure values occurring in the bounce chamber. Force control is obtainable by regulating the flow of pressurized fluid into the bounce chamber in response to the determination. Peak pressure values are sensed by pressure gauge or transducer means to determine the peak values of driving force being exerted on the top of the pile and control of the pile driver operation can be manually or automatically obtained.

26 citations


Journal ArticleDOI
01 Jan 1971-Vacuum
TL;DR: In this paper, the performance and limitations of the capacitance manometer and the quartz high precision pressure gauge are discussed, and a deadweight primary pressure standard for checking the absolute accuracy of the instruments is also described.

24 citations



Journal ArticleDOI
TL;DR: In this paper, an interpretation of initiation pressure hysteresis phenomena for fixed point pressure calibration is presented according to the theory of nucleation in condensed systems and substantiated for the bismuth I-II point by hydrostatic pressure experiments with a manganin pressure gauge.
Abstract: An interpretation of initiation pressure hysteresis phenomena for fixed‐point pressure calibration is presented according to the theory of nucleation in condensed systems and is substantiated for the bismuth I–II point by hydrostatic pressure experiments with a manganin pressure gauge. Kinetic initiation and completion of the bismuth I–II transformation were observed at constant pressure and temperature, and several different isobaric initiation pressures were measured at the same temperature. An asymmetrical relationship of the equilibrium pressure between the initiation pressures of the forward and reverse transformations was measured, and it was demonstrated that the high‐pressure side of the strain hysteresis of initiation is within 0.17 kbar of the equilibrium pressure. The microstructure and thickness of the sample influenced the initiation pressures and the region of indifference, but the center of the region appeared reproducible. A region of indifference of 0.03 kbar was measured. The origin of t...

Journal ArticleDOI
TL;DR: In this article, the authors presented a highly accurate and precise pressure gauge, which utilizes the 35°C, 2005 Hz dielectric constant of an ionic crystal CaF2, and was calibrated at the National Bureau of Standards over the pressure range 0-2.5 kilobars.
Abstract: A highly accurate and precise pressure gauge, which utilizes the 35°C, 2005 Hz dielectric constant of an ionic crystal CaF2, is presented. The prototype gauge was calibrated at the National Bureau of Standards over the pressure range 0–2.5 kilobars, and the defining equation was found to be C/C0=1−AP+BP2, where C0 is the zero pressure capacitance, C is the capacitance at absolute pressure P, and the characteristic constants A and B are A=3.7801×10−6/(bar) and B=2.739×10−11/(bar)2. The gauge is stable and accurate over this range at the 0.01% level, and indications are that this type of gauge may be useful at much higher pressures and refined to even higher accuracies.

Journal ArticleDOI
TL;DR: An improved field ion microscope (FIM) technique has been developed for the neon gas imaging of gold specimens as discussed by the authors, which produces images which are stable at best image voltage at a tip temperature (TT) of 30 K or less.

Journal ArticleDOI
TL;DR: Turbulent incompressible air flow in-stream static pressure fluctuations measurement, describing bleed type pressure transducer theory, design and operational characteristics as mentioned in this paper, is described in detail.
Abstract: Turbulent incompressible air flow in-stream static pressure fluctuations measurement, describing bleed type pressure transducer theory, design and operational characteristics

Patent
04 Jan 1971
TL;DR: In this article, the authors present a system for monitoring tire pressure on a vehicle such as a passenger automobile, truck, or bus, where individual hub units are mounted on each wheel unit, each hub unit including a radio transmitter, and a radio receiver is positioned leading to the vehicle operator.
Abstract: For monitoring tire pressures on a vehicle such as a passenger automobile, truck or bus, individual hub units are mounted on each wheel unit, each hub unit including a radio transmitter, and a radio receiver is positioned leading to the vehicle operator. Each hub unit includes bellows means responsive to tire pressure to operate a visual pressure gauge on the hub unit which may be observed by the operator when the vehicle is stopped, and to energize the transmitter when the pressure decreases to a preselected value. For dual wheel units used on heavy duty vehicles, a common bellows means may respond to the lower pressure of the two tires to indicate the lower pressure on the gauge and transmit the fault signal. The dual wheel unit may include two bellows means for actuating separate visual gauges for the two tires, with the two bellows mechanisms energizing a common transmitter, or alternatively energizing respective separate transmitters. The hub unit may include valve means for equalizing tire pressures.

Patent
14 Dec 1971
TL;DR: In this paper, a system for measuring the pressure in a conduit or line in which finely divided solids are transported in gas, the single inlet of the primary measuring gauge is connected to the transport line by a tube whose outlet is preceded by a first filter.
Abstract: In a system for measuring the pressure in a conduit or line in which finely divided solids are transported in gas, the single inlet of the primary measuring gauge is connected to the transport line by a tube whose outlet is preceded by a first filter. A differential pressure limit gauge has one inlet connected to the line by a similar filter containing tube and its other inlet connected to the outlet of the first tube so as to measure the pressure drop across the first filter and thereby indicate when either filter may be clogged. The differential gauge produces an alarm signal to indicate filter condition.

Journal ArticleDOI
TL;DR: In this paper, the solution to problems of the measurements of unsteady forces and pressures in fluid mechanics is discussed, particularly regarding the selection of measurement system, and a number of examples of solution processes to various measurement problems are outlined.
Abstract: The solution to problems of the measurements of unsteady forces and pressures in fluid mechanics is discussed, particularly regarding the selection of measurement system. A number of examples of solution processes to various measurement problems are outlined.

Proceedings ArticleDOI
01 Jun 1971
TL;DR: In this article, the authors measured the thermal dissociation rate of undiluted nitrogen in a shock tube over 5700 to 12,000 K range, using pressure measurements, and showed that the rate was in the range of
Abstract: Thermal dissociation rate of undiluted nitrogen in shock tube over 5700 to 12,000 K range, using pressure measurements

Patent
29 Sep 1971
TL;DR: In this article, a pressure gauge includes a transducer support 25 carrying a semi-conductor body 10 having a plurality of piezo-resistive strain sensing elements 13 formed therein, mounted in an enclosure 32, 22 containing a fluid at a predetermined pressure, a bore 28 extending through the enclosure part 22 to allow fluid whose pressure is to be measured to communicate with a cavity 26 defined by the support 25 and semi conductor body 10 and thereby flex the sensing part of body 10.
Abstract: 1,248,087. Semiconductor devices. FERRANTI Ltd. 27 Feb., 1970 [28 Feb., 1969], No. 10732/69. Heading H1K. [Also in Division G1] A pressure gauge includes a transducer support 25 carrying a semi-conductor body 10 having a plurality of piezo-resistive strain sensing elements 13 formed therein, mounted in an enclosure 32, 22 containing a fluid at a predetermined pressure, a bore 28 extending through the enclosure part 22 to allow fluid whose pressure is to be measured to communicate with a cavity 26 defined by the support 25 and semi-conductor body 10 and thereby flex the sensing part of body 10. The transducer 10, Fig. 1, comprises superimposed P-type substrate 11 and N-type epitaxial layer 12 having formed in its central region 14 diffused P-type sensing resistive elements 13, P-type layer 11 being removed from region 14 to allow layer 12 to flex. Four resistors 13 are provided at the centre of 14 and two pairs os U-shaped resistors 13 at its periphery which resistors are connected by aluminium strips 17 to terminals 18. In operation two of the central resistors 13 and two of the U-shaped resistors are connected to form a Wheatstone Bridge the output from which varies in response to changes in pressure on region 14. Others of the resistors 13 may be employed as balancing or calibrating resistors, or pairs may be connected in series and used as temperature sensors together with thin film trimming resistors to provide a temperature independent output. The silicon support 25 is bonded to a metal tube 23 having a matching coefficient of expansion and which extends through header 22 forming part of the hermetically sealed enclosure. The pressure in the enclosure may be a vacuum or can be preselected by a valve connected to tube 33 communicating with metal can 32. Instead of mounting the pressure gauge to anchorage 42 by means of screwthreaded part 38 of header 22 the metal can 32 may be provided with a screw-threaded block to which is attached tube 33, Fig. 3 (not shown).

Journal ArticleDOI
TL;DR: In this paper, the authors deal with an investigation aimed at the development of techniques, which permit the measurement of well-defined average values of oscillating pressures, and three different methods developed and tested at DFVLR are described.
Abstract: Strong pressure oscillations of high frequencies and high amplitudes occur in the region of turbomachine rotors. The measurement of the average pressures resulting from these oscillations is one of the most important measuring problems in turbomachinery, because the pneumatic measuring systems usually used in such tests yield average pressures which normally do not agree with the true time-integrated values. This paper deals with an investigation aimed at the development of techniques, which permit the measurement of well-defined average values of oscillating pressures. Three different methods developed and tested at DFVLR are described. Two of them—a hydraulic and a mechanical one—are able to measure the true time-averaged pressures with an accuracy better than 0.5 percent of the acting pressure amplitude. The third procedure is based on an evaluation method by means of which the average pressures indicated by special pneumatic measuring systems can be correlated to the true time-weighted values. Experimental and computed results are presented showing a very good agreement.

Journal ArticleDOI
TL;DR: In this article, a static vapor pressure device was used to degass a mixture of methyltliethylarnine without change in composition. But the measurement accuracy was only within 0.03"C.
Abstract: EXPERIMENTAL The experimental methods and apparatus were the same described previously (4-7). The apparatus was a static vapor pressure device in which the mixture sample may be degassed without change in composition. The apparatus. including the manometers, sample flasks, and glass manifold, was suspended in a constant temperature bath and could be agitated to hasten equilibrium. The pressures were measured with mercury manometers read to 0.05 mm of Hg with a cathetometer. Since the pressures being measured may exceed the manometer length (about 130 mm), a back pressure must be applied from an external source or reference solution of known wpnr pressure. In the present work, chloroform was used as reference with the methyltliethylarnine system when needed. Chloroform vapor pressures (Table I) were run in the same apparatus by use of an external back pressure measured with an external mercury manometer. All manometer readings were corrected for temperature and gravity. The vapor density correction was below the measurement precision. Temperature was controlled to within 0.01"C. Temperature measurement was with a calibrated glass thermometer with 0.1"C gradations. The accuracy is believed to be within 0.03"C. Amine analysis was by acid titration for amine concentrations less than 90 wt %. For higher concentrations gas chromatography was used. Accuracy ranged from better than 0.1 mol % at low amine concentrations to perhaps 1 mol % at the highest amine concentrations.

Journal ArticleDOI
TL;DR: In this paper, a form of pressure cell by which the pressure distribution across a deforming billet can be measured is described. But it is considered that this new device offers advantages in terms of simplicity of manufacture and maintenance.

Patent
23 Jul 1971
TL;DR: In this paper, a pressure gauge utilizes a Bourdon tube and associated mechanical linkage to indicate pressure on a calibrated dial between predetermined limits, and fixed high pressure and low pressure limit switches are fixedly secured to a carrier having lost motion connections with the Bourdon tubes and said linkage.
Abstract: A pressure gauge utilizes a Bourdon tube and associated mechanical linkage to indicate pressure on a calibrated dial between predetermined limits. High pressure and low pressure limit switches are fixedly secured to a carrier having lost motion connections with the Bourdon tube and said linkage. Adjustable high pressure and low pressure stops on the face of the instrument positively interrupt the movement of the instrument pointer and thereby lock said linkage. Continued expansion or contraction of the Bourdon tube utilizes said lost motion connections with said switch carrier to operate the high pressure and low pressure limit switches in proper sequence. The principle of operation is also adaptable to Bourdon tube temperature gauges.

Journal ArticleDOI
TL;DR: In this article, a survey of the properties of certain resistors (manufactured by the Allen-Bradley Company) under hydrostatic pressure up to 11 kilobars at 295, 77, and 4.2 K was made.
Abstract: A survey has been made of the properties of certain resistors (manufactured by the Allen‐Bradley Company) under hydrostatic pressure up to 11 kilobars at 295, 77, and 4.2 K. It is found that the resistance of the resistors (nominal value 220 Ω) decreases markedly with pressure and they may provide very sensitive pressure gauges. The reproducibility during a single pressure cycle is completely satisfactory, although the resistors show hysteresis effects when the pressure is removed.

Patent
17 Feb 1971
TL;DR: In this article, an absolute pressure transducer including an open bellows, a suspension system, and a sealed bellows is described, which can yield a torque about a single sensitive axis when pressure is applied.
Abstract: Disclosed is an absolute pressure transducer including a mechanical assembly comprising an open bellows, a suspension system, and a sealed bellows arranged to yield a torque about a single sensitive axis when pressure is applied to the open bellows and an electronic circuit comprising a detector for sensing angular motion and a torquing device to restore the mechanical assembly toward its null position. The amount of electrically generated torque necessary to balance the pressure induced torque is proportional to, and a measure of, the applied pressure.

Journal ArticleDOI
TL;DR: In this paper, a capillary rheometer was used to measure both viscous and elastic properties of polystyrene melts, and the elastic property was determined from the exit pressure, which is obtained at the tube exit when the straight line portion of the axial pressure profile is extrapolated to the exit of the tube.
Abstract: Measurements were taken of both viscous and elastic properties of polystyrene melts, using a capillary rheometer recently constructed byHan. The viscous property is determined from the slope of the axial pressure distribution, and the elastic property is determined from the exit pressure, which is obtained at the tube exit when the straight line portion of the axial pressure profile is extrapolated to the exit of the tube. Previous studies ofHan demonstrated that the exit pressure thus obtained can be correlated with die swell ratios, and that the exit pressure is equal to the normal stress difference for polymer melts in fully developed viscometric flow. The present study of polystyrene melts corroborates all previous correlations obtained with high density polyethylene and polypropylene melts as regard the exit pressure measurements. A salient feature of the method employed here is that it requires only a single capillary, long enough to assure that flow is fully developed.

Patent
03 Nov 1971
TL;DR: In this article, a hydraulically operated test winch is used to test the rated load, speed, and braking capabilities of a hoist, which imposes a predetermined load or line pull at a predetermined speed on the hoist line.
Abstract: Apparatus for testing the rated load, speed and braking capabilities of a hoist comprises a hydraulically operated test winch which imposes a predetermined load or line pull at a predetermined speed on the hoist line. The hoist line is connected to the test winch cable by a lever and pulley arrangement. A load cell responsive to lever movement and, therefore, the load imposed, provides a visual readout thereof at an operation control station. Load size is remotely adjustable from the control station by a load control rheostat which controls an electric-hydraulic pressure control valve which, in turn, adjusts the pressure relief setting of a pressure relief valve between a hydraulic winch motor and the hydraulic pump for that motor. A load control pressure gauge at the control station is responsive to output pressure of the electric-hydraulic pressure control valve for the pressure relief valve and is calibrated to indicate pounds of line pull or load which the hoist being tested can exert to enable the operator to set the load control rheostat accordingly. Load speed is remotely adjustable from the control station by a speed control rheostat which controls another electric-hydraulic pressure control valve which, in turn, operates a cylinder to adjust the speed setting of a servo-stem speed control device on the pump. A speed control pressure gauge at the control station is responsive to output pressure of the other electric-hydraulic pressure control valve for the speed adjustment cylinder and is calibrated to indicate feet per minute of hoist line speed to enable the operator to set the speed control rheostat accordingly.

Patent
30 Apr 1971
TL;DR: In this paper, an electrical circuit is disclosed which provides an output which indicates the ratio of a sensed pressure differential to a sensed absolute pressure and thereby approximates the Mach number of air flow in a duct.
Abstract: An electrical circuit is disclosed which provides an output which indicates the ratio of a sensed pressure differential to a sensed absolute pressure and thereby approximates the Mach number of air flow in a duct. A pair of transducers respectively sense the differential between total and static pressure, and static pressure, per se, in the duct. The pressure differential signal provides an input to an operational amplifier circuit, while the absolute pressure signal forms part of a feedback loop to the operational amplifier. A non-linear compensation network is provided to prevent null drift of the operational amplifier.

Patent
03 Mar 1971
TL;DR: In this article, the combination of a liquid container and a differential pressure gauge is used to measure the difference between the gas applied to the liquid surface and the pressure between the top of pipe 3 and the tap 4, which pressure difference is related to the volume of the container.
Abstract: 1,223,848 Liquid level indication WHITBREAD & CO Ltd Oct8, 1968 [Oct 10, 1967], No46307/67 Heading G1H In the combination of a liquid container I, such as for beer or other beverage, a down tube 2, connected via an upwardly extending pipe 3 to a dispensing tap 4, and a connector 5, for the application of a compressed gas such as carbon dioxide from a cylinder 8 via a pressure reducing valve 7 to the surface of the liquid, a differential pressure gauge 9 is connected in a pipe line 14 so as to measure the difference in pressure between the gas applied to the liquid surface and the pressure between the top of pipe 3 and the tap 4, which pressure difference is related to the volume of the liquid in the container A normally closed electrically operated solenoid valve 15 in the pipe 14 between pipe 3 and a pipe 17 containing the pressure gauge 9 and a similar normally open solenoid valve 19 in a pipe 18 by-passing the gauge 9 are arranged in a control circuit to close valve 19 and open valve 15 when a volume reading is required by closing a switch 28, Fig3 (not shown)

01 Dec 1971
TL;DR: In this paper, an equation for computing the resonant frequency of liquid-filled transient pressure measuring systems is given and experimentally verified for computing their response to non-condensable gas bubbles.
Abstract: An equation is given and experimentally verified for computing the resonant frequency of liquid-filled transient pressure measuring systems. Resonant frequencies of 100 to 1000 Hz are typical of those systems tested. The effect of noncondensable gas bubbles on system response is described. A method for determining transducer volumetric compliance is presented. An example system is described and analyzed to demonstrate the use of the theory.