Showing papers on "Pressure measurement published in 1974"

Recovery Speed of Axial Flow Gas Blast Interrupter: Dependence on Pressure and dI/dt for Air anf SF6

Abstract: The dependence of the recovery speed on the pressure and on dI/dt was obtained, for both air and SF6, in a model interrupter of axial flow type employing a Laval nozzle. The measurements were carried out for pressures extending from 100-600 psi (6.8-41 atm) and for dI/dt values ranging from 5-30 A/?s. For both gases the recovery speed was found to increase with pressure, varying as the first power for air and as the 1.4 power for SF6. A stronger than expected dependence on dI/dt was also found for both air and SF6, the recovery speed varying inversely as the square in each case.

Miniature absolute pressure transducer assembly and method

Abstract: A transducer assembly for measuring absolute pressure utilizing a glass substrate and a thin silicon diaphragm upon which is diffused a piezoresistive bridge circuit. Bridge circuit components are properly oriented and connected to bonding pads formed on the silicon. The glass substrate has a circular well formed therein having a diameter at least as large as the diameter of the diaphragm. Conducting leads are deposited on the glass substrate in a pattern matching that of the bonding pads on the silicon. The silicon is bonded to the glass substrate with the silicon diaphragm overlying the well in the glass and the bonding pads overlying the conducting leads deposited on the glass. The bond provides a hermetic seal around the well, trapping a predetermined pressure therein which serves as a reference pressure. Ambient pressure variations cause stress variation in the diaphragm, resulting in unbalance of the bridge which can be sensed with associated circuits to give an indication of the ambient pressure.

Pressure Distribution on the Body Surface of Swimming Fish

Abstract: 1 Pressures on the body surface of bluefish, swimming at 0-6 mph, compared to lateral pressure, were recorded using strain-gauge manometers 2 While in motion, the front of the fish is subject to a head-on pressure exactly equal to that calculated using the Pitot equation In salt water, this pressure, in cm H 2 O, is equal to the speed, in mph, divided by 098, all squared 3 On the widest diameter the pressure is negative while swimming This is attributable to the Bernoulli effect 4 Pressure on the base of the tail is still negative, but not so negative as on the shoulder, in live swimming fish The body and tail motion seem to draw water away from the peduncle of the tail, thereby diminishing turbulence 5 In a dead fish the pressure at the base of the tail is positive, suggesting the possibility of boundary-layer separation and increased drag in dead fish towed through water 6 The hydrodynamic pressures in fish swimming are often as great as the hydrostatic pressures encountered in animals of equal length subjected to gravity We conclude that body defences against hydrodynamic pressure would also be useful against gravitational hydrostatic pressure 7 Body structures which appear to resist hydrodynamic pressures in water and hydrostatic pressures on land are the skull, the vertebral column, and the circulatory system 8 Transition from aquatic to terrestrial life may have been facilitated by adaptation to the pressures encountered on the body surface while swimming

Metal vapor confinement in vacuum

Abstract: A new method for confining a metal vapor at a pressure of about 10−3 Torr, with extremely low loss of metal into the vacuum chamber surrounding the metal cell, has been demonstrated; it consists in recycling the metal, condensed in the liquid state; its return to the high pressure region is ensured by capillarity. Two versions of the new cell, built for different applications, are described: a heat pipe heated lithium cell, characterized by a high uniformity of temperature, and a cesium cell, equipped with a surface ionization gauge for cesium pressure measurement, and a LiF window. Measurements carried out with the surface ionization gauge in the cesium cell led to a ratio 103 between the cesium atom flux at the center of the canal and at its port. The contribution of direct metal loss from the hot central region of the canal and that due to desorption from the canal ports is discussed.

Liquid volumetric line leak testing apparatus and method

Abstract: Apparatus and method to determine and certify the tightness, or detect, measure the rate of and locate a leak, in underground lines extending from an underground storage tank at an automotive service station to an above-ground fuel dispensing apparatus. The outlet of a small, portable liquid pump is coupled to an available opening in or under the service station island pump or dispenser, which opening is in unobstructed communication with the lines leading from the tank, so that fluid may be discharged into the dispenser and line to maintain a test pressure therein. A pressure gauge senses the line pressure, and a calibrated burette which supplies make up gasoline to the pump inlet provides means of precise volume measurement whenever the pump is operated to restore the pressure in the line as a consequence of leakage or other cause.

Air conditioner servicing unit

Abstract: Apparatus for servicing automobile air conditioning systems, as for charging them with refrigerant and compressor lubricant. Hoses connect to the high and low pressure charging fittings on the system and lead to pressure gauges for checking the system. The high pressure hose also leads to a dumping valve for emptying the system. The low pressure hose is connected through control valves (a) to a vacuum pump for purging the system, and also through a constant flow valve both (b) to a pressurized source of refrigerant liquid and (c) to a pressurized source of oil. Charging is done to the suction side of the compressor while it is operating. The flow valve passes liquid through a small orifice at a controlled pressure drop. This limits oil flow to a rate, such as one ounce in 45 seconds, slow enough to avoid damaging the compressor, and meters refrigerant in liquid state at a constant rate, e.g. one pound per 90 seconds. As refrigerant leaves the metering valve it is atomized and vaporized before entering the system. Preset timers control the periods of constant flow of oil and refrigerant and thereby meter the quantities charged to the system. A third hose and pressure gauge are provided for servicing those systems having a pressure ratio valve between the evaporator and the compressor.

Measurement of CO2‐laser‐generated impulse and pressure

Abstract: Measurements of impulse transferred to large metallic targets in air produced with a variable‐pulse‐length high‐power 10.6‐μm laser beam are presented. Peak focal spot pressure measurements in Plexiglas are also presented which show that the peak pressure increases approximately as the 3/2 power of the peak power density and that at a fixed power density higher peak pressures are obtained by increasing the focal spot size.

Apparatus for the measurement of light reflection of cholesteric mesophases at high pressures

Abstract: An apparatus for determining the wavelength of maximum reflection of light lambda R of cholesteric mesophases at high static pressures is described. The arrangement of the whole high pressure equipment is briefly outlined. The pressure chamber allows optical measurements up to 5000 bar and can be thermostated by oil on the outside. Details of the sample cell are illustrated. The generated oil pressure is transmitted to the sample layer of 25 mu m by means of a thin Teflon membrane. By way of example the effect of pressure on the reflection of a cholesteric mixture of cholesteryloleylcarbonate and cholesterylchloride is shown. In a definite pressure range the sensitivity of lambda R to pressure is so large that it can provide a new accurate means of pressure measurement. This behaviour is probably caused by a pretransition effect of the mesophase.

Monolithic polycrystalline-silicon pressure transducer

Abstract: A monolithic pressure transducer using polycrystalline silicon for both the diaphragm material and an integral piezoresistor has been fabricated. The device can be made with good repeatability and with easily varied diaphragm thickness. Electrical-output linearity is very good over a pressure range of 0?11 cm Hg for a 2.4 ?m diaphragm having an area of 0.00136 cm2.

Measurement of gas production of microorganisms

Abstract: A simple apparatus and method is disclosed for measuring gas production by microorganisms using a pressure transducer to sense pressure buildup by members of the Enterobacteriaceae group of bacteria. The test system consists of a 5.0 psid pressure transducer and a pressure equalizer valve attached to the metal cap of a 20 x 150 mm test tube with gas pressure being recorded on a strip-chart recorder.

Underwater instrument case

Abstract: An underwater diver's instrument case for tethering an underwater watch and depth gauge to a pressure gauge suspended from a hose leading from a regulator mounted on a scuba tank. The case includes a housing formed with a compartment defining pressure gauge and depth gauge cavities. The housing includes a retainer which retains the pressure and depth gauges in their respective cavities. The cover is formed with windows overlying the faces of the respective gauges to enable viewing thereof. Thus, the case may be conveniently mounted to a pressure gauge conventionally suspended from a scuba diver's air regulator by means of a hose and the depth gauge will be readily available for convenient viewing during a dive much the same as the pressure gauge.

Blood pressure measuring means

Abstract: Blood pressure measuring apparatus utilizes a cuff containing an inflatable bladder which is inflated by pump means through the intermediary of a connecting means which also interconnects a pressure gauge with the bladder the apparatus being formed to enable interconnection of the bladder the pump means and the pressure gauge by an integral connecting means in the form of a unitary elongated flexible tube.

Continuous negative pressure chamber for infants

Abstract: A continuous negative pressure chamber for treating infants having Idiopathic Respiratory Distress Syndrome including an enclosure with two of the opposed walls of the enclosure each having an opening aligned with each other and each mounting an adjustable iris diaphragm for adjustably engaging the neck and pelvic area of an infant placed in the chamber. A pressure manometer as well as a pressure relief valve are mounted to the chamber. The chamber has a vacuum inlet to which a vacuum source means is connected for producing a continuous negative pressure in the chamber.

Blood pressure manometer

Abstract: A blood pressure manometer comprising a pneumatic cuff to be wrapped around the limb of a person and, connected to the cuff, a pressure indication system comprising a housing, preferably with a longitudinal channel, visual pressure indication scale markings along the housing, and a resiliently expandable balloon-like aircontaining member, preferably confined by the channel, attached at one end to the housing, the other end of the expandable member being free to expand along the length of the housing. The expansion of this member is directly related to the pressure delivered from the pneumatic cuff, the free end of the expandable member indicating blood pressure in accordance with the pressure indication markings on the pressure scale.

Subsurface transient pressure testing apparatus and method of use thereof

Abstract: Wireline apparatus and method for measuring pressure downhole in well tubing comprising a main plug body which seats in a seating nipple forming part of the tubing, a pressure gauge in communication with the tubing below the main plug body, and means for equalizing the tubing pressure above and below the seated main plug body so that the apparatus may be removed from the well.

Pressure and temperature dependences of acoustic‐wave velocities in polycrystalline bismuth

Abstract: Ultrasonic velocity measurements have been made on polycrystalline bismuth as a function of temperature and pressure over the temperature and pressure ranges 23–160°C (at atmospheric pressure) and 0–28.4 kbar (at 23°C), respectively. Special care was taken with the room‐temperature and pressure measurements in an attempt to resolve discrepancies in previously reported sound velocity measurements. The data have been used to determine the pressure‐temperature dependences of various elastic parameters, including the (discontinuous) changes across the I–II and II–III phase boundaries. The pressure data are the first that have been taken under truly hydrostatic conditions, and they are compared to results obtained with solid pressure transmitting media.

Temperature compensated pressure gauge

Abstract: A pressure gauge visibly indicating on a dial face the pressure of a gas medium being monitored as it relates to a predetermined minimum allowable pressure and also simultaneously as to a maximum allowable pressure which together define an acceptable operating zone over a predetermined temperature range, the gauge including a first Bourdon coil internally communicating with the gas medium being monitored and mounted in a gauge housing in which is sealed a gas medium similar in pressure/temperature characteristic to the monitored gas medium and at the minimum allowable pressure, and also including a second Bourdon coil mounted in the housing and in which is sealed a similar gas medium at the maximum allowable pressure, a movable end of the first coil being coupled to a dial pointer and a movable end of the second coil being coupled to a dial flag, the housing being located relative to the temperature environment of the gas medium being monitored so that all components and gas mediums in the housing being subject to essentially the same temperature as that of the monitored gas medium.

A Pulsed Discharge Vacuum Gauge

Abstract: New vacuum gauges and their controls have been developed. They employ a pulsed crossedfield discharge which shows excellent pressure measurement application characteristics. Experiments have shown that a high-voltage pulse generator and a specific measuring circuit with a PIG tube can measure pressures ranging from 2×10-8 to 1×10-3 Torr. Accuracy better than 0.6% is obtained in 10-6 and 10-5 Torr range. A pressure change caused by measurement, which has been a serious defect of conventional vacuum gauges, has been revealed as being very slight.

Computer Detection of Distortion in Arterial Pressure Signals

Abstract: An application of the mathematical concept of curvature to the detection of distortion in arterial pressure signals is described. Curvature is defined and examples of digitally filtered pressure tracings show the relationship between curvature and the degree of damping. Even though curvature is also a function of the cardiovascular system producing the signal, the average sum of curvature can generally distinguish control signals from signals distorted by moderate amounts of blood or air in the catheter systems. Selected pressure signals with their associated sums of curvature show the properties and limitations of curvature for discriminating between the changes in the cardio-vascular system and distortion of pressure signals.

A miniature extractor gauge for the UHV

Abstract: The design and performance of a miniaturized hot filament ionization pressure gauge, specially developed for the CERN intersecting storage rings, is described. It is mounted on a standard metal flange with ceramic feedthroughs and fits into an aperture of 15.7 mm. The gauge is of the extractor type and has a sensitivity factor for nitrogen of about 5 Torr−1. Its low pressure limit, about 5×10−12 Torr nitrogen equivalent, is mainly due to x rays. These two characteristic figures have been obtained, in spite of the gauge's smallness, by an optimization of most of the geometrical and electronical parameters. Some problems, seriously affecting the gauge’s performance, and particularly arising from its size, such as space charge effects and thermal outgassing, are discussed.

Electronic internal combustion engine ignition spark vacuum and speed advance system

Abstract: Two series of phase displaced leading and trailing electrical signal wave forms of a potential level proportional to engine speed are generated in timed relationship with the engine and an absolute pressure transducer produces an engine manifold absolute pressure electrical signal of a potential level proportional to engine manifold absolute pressure. The engine manifold absolute pressure signal and the leading and trailing electrical wave form series are compared by respective comparator circuits. While the potential level of each of the leading electrical signal wave forms is equal to or greater than that of the engine manifold absolute pressure signal, the corresponding comparator circuit produces an output ignition dwell signal and when the potential level of each of the trailing electrical signal wave forms has increased to that of the engine manifold absolute pressure signal, the corresponding comparator circuit produces an output ignition signal. An electronic ignition circuit is responsive to each of the ignition dwell signals for completing and to each of the ignition signals for interrupting, respectively, an energizing circuit for the primary winding of an associated ignition coil.

Pressure distribution on a vectored-thrust V/STOL fighter in the transition-speed range

Abstract: A wind-tunnel investigation has been conducted in the Langley V/STOL tunnel with a vectored-thrust V/STOL fighter configuration to obtain detailed pressure measurements on the body and on the wing in the transition-speed range. The vectored-thrust jet exhaust induced a region of negative pressure coefficients on the lower surface of the wing and on the bottom of the fuselage. The location of the jet exhaust relative to the wing was a major factor in determining the extent of the region of negative pressure coefficients.

Power Absorption in High Power Microwave Discharges

Abstract: Measurements on RF power absorption in microwave discharges at 2.45 GHz, at pressures from 1 to 30 Torr in N2 and from 1 to 500 Torr in Ar, are described. A linear slow-wave structure of the strapped-bar type was employed for coupling RF energy to the plasma. From measurements on the plasma volume and on the total power absorbed, the variation with gas pressure of the RF power density in the plasma was obtained. For an incident power of 1 kW, power densities as high as 2-3 W/cm3 over relatively large plasma volumes could be achieved. The experimental data were used to calculate the pressure dependence of the electron density in an argon plasma, for an incident power of 1 kW.

Flight Test Base Pressure Results for Sharp 8° Cones

Abstract: NALYTIC studies of the hypersonic near wake problem often make use of base pressure measurements and resulting correlations in order to verify and/or upgrade calculated results. Although an extensive amount of base pressure data have been obtained from wind-tunnel test experiments only a limited amount of results are available for interference free data under high Mach number conditions.J ~ 3 In addition, because available flight test data on base pressures have been obtained with pressure gages whose full scale ranges were 0.1 psia or greater, published results on flight test base pressures4 ~ 8 correspond primarily to moderate or high Reynolds number conditions. The purpose of the present Note is to present additional base pressure results obtained through use of low range gages (0.01 and 0.05 psia full scale) on three conical flight vehicles of 8° half angle. These data represent a set of unique flight test base pressure measurements extending to low Reynolds number and are shown herein along with other results, also previously unpublished, for 8° half-angle conical vehicles as obtained through use of 0.1, 1.0 and 2.0 psia gages. All data correspond to zero angle-of-attack conditions at a freestream Mach number of (M^ ~)20. Results are available for three types of heatshield material which can be categorized as high, medium, and nonablators corresponding to turbulent mass loss parameters of \_(m/pAv)T~~\ 0.05, 0.01, and 0.0, respectively. Taken together, the complete set of data represents a composite summary of flight test base pressure data for 8° half-angle cone vehicles covering a range of Reynolds number of (Re^L ^) 2 x 105 to 3 x 108. 2. Experimental Technique The low range data discussed herein were measured through use of dual range gages which were located for each vehicle at a radial location of (r/R = ) 0.54. For this stretched diaphragm gage the dual output feature was accomplished through use of two amplifiers which independently provided 5 v d.c. outputs at pressure levels of 0.01 psia and 0.05 psia. Response time tests and analyses determined that a small (10%) bias correction to the local raw data was appropriate in order to account for time lag effects associated with the pressure gage assembly. This correction has therefore been applied to all the low range data presented herein. Since final results have been validated to ± 5% full scale, only data greater than 5% full scale are presented. The data obtained with the 0.1,1.0, and 2.0 psia gages, as shown herein, correspond to results which were 10% full scale or greater. Data are presented for each of three radial locations (r/R = 0, 0.33, and 0.46) and for the three mass loss parameters previously "described. The noted results were determined from measured