Showing papers on "Overpressure published in 1993"

Overpressure valve for a packaging container

Abstract: Overpressure valves for packaging containers are supplied in a roll, transported in this form to a packaging machine, separated here and attached to packaging containers by means of an adhesive coated surface. For this purpose the overpressure valves have a layer of emulsion bonding on their underside. To prevent individual layers of the roll from sticking together, the overpressure valves have an adhesive-repelling layer on their top side. The overpressure valves are connected to one another in one piece and in a row, and are separated consecutively in a packaging machine.

Study of The Blast Waves from the Explosion of Nonspherical Charges

Abstract: The blast wave patterns from the explosion of cylindrical charges are very complex and the pressure-time histories exhibit multiple shocks. The accurate assessment of the blast wave parameters (positive peak overpressure, duration, and the positive impulse) thus is not a simple task. In this paper a simple system is described for studying the blast waves from the explosion of small cylindrical charges together with comprehensive methods to analyse the experimental results. The assessment of the near-field/far-field behaviour also has been studied.

Differential pressure device

Abstract: A pressure sensing transmitter (10) is provided that has high overpressure protection. The transmitter (10) includes a housing (12) having a first cell(14), a second cell (16), a sensing chamber (18), first and second pressure signal receiving means (26, 28), and a differential sensor chip (22) for measuring the pressure differential between the first and second pressure signal receiving means (26, 28). Each cell further includes a cylinder (30, 38) with a clearance of an overpressure diaphragm (32, 40) mounted on the housing, an isolation diaphragm (34, 42) mounted on the other face, and a channel (36, 44) coupling the overpressure (32, 40) and isolation diaphragms (34, 42) and further coupling one cell to the first pressure signal receiving means (26) and the other cell to the second pressure signal receiving means (28). Each overpressure diaphragm (32, 40) is positioned such that an overpressure protection cavity (46, 48) is formed between it and the housing. The first cell cavity is further coupled to the second pressure signal receiving means (28) and the second cell cavity is further coupled to the first pressure signal receiving means (26).

Study of the Blast Wave Parameters from Small Scale Explosions

Abstract: Although the science of blast overpressure is well understood there are major difficulties in obtaining accurate values for peak overpressure, positive duration, and positive impulse. These parameters are required to assess damage potential of blast overpressures. This paper describes the problems associated with such measurements and how the problems can be overcome by the use of known analytical techniques based on the modified Friedlander equation. Other methods used include curve smoothing of the pressure-time history and integration to obtain impulse values through which the curve decay parameter can be found. Several different analytical methods are compared. The experiments have been carried out on small charges (200 g and 400 g) and the results obtained analysed to assess far-field distances for such charges. This has been achieved by comparing peak overpressure values with the scaled distance.

Distribution of sub-surface pressure in the Norwegian Central Graben and applications for exploration

Abstract: The Norwegian Central Graben contains a distinctive three-tiered sub-surface pressure system. This pressure system has an important effect on distribution of oil and gas fields, generation and migration of hydrocarbons, reservoir qualities and drilling procedures. A number of mechanisms have been proposed for the development of overpressure. In this paper, five are briefly discussed: thermal expansion of water, sedimentary compaction, rate of sediment burial, volumetric increases due to generation of hydrocarbons, and column heights of major oil and gas fields. None of the factors are mutually exclusive and all contribute to the development of overpressure in the Norwegian Central Graben. Utilizing drill-stem tests (DSTs), repeat formation tests (RFTs) and sonic and density logs, the horizontal and vertical boundaries of the three-tiered pressure system of the Norwegian Central Graben have been mapped. A shallow hydropressure system exists down to 1000–2000 m, underlain by a transition zone where pressures abruptly increase to the fracture level where overburden and fluid pressure are in balance. Under the transition zone, a geopressure zone exists to 3000–4000 m, within which pressures increase with depth at a hydrostatic rate. In the centre of the graben, this compartment is underlain by a second transition zone and a deep, high temperature, high pressure zone. The location and depth of the boundaries of the two upper pressure compartments and transition zones are more dependent on temperatures than lithologies or tectonic movements. Within the deep, high pressure zone, variations in pressure gradients indicate the presence of a number of smaller pressure cells, probably separated by faults. The identification and prediction of overpressured zones can have a significant effect on exploration programmes. From the drilling standpoint, prediction of sharp increases in pressure is a major safety factor, reducing the danger of well blowouts and allowing the operator to be adequately prepared for a number of drilling hazards. In potential reservoirs, overpressure reduces net overburden, thereby reducing porosity loss due to compaction. Sub-surface pressure variations have a significant effect upon hydrocarbon migration as oil and gas will attempt to move from high to low pressure compartments. Defining pressure variations from well to well can give indications of sealing and non-sealing faults. The pressure configuration has a significant effect upon the distribution of discovered hydrocarbons in the Central Graben. Most recoverable hydrocarbons are found in the first sealed permeable bed in the middle pressure compartment, overlying or adjacent to the transition zone above the deep, high pressure compartment. This includes the Cretaceous to Danian chalk fields in the centre of the graben and the Jurassic sand-reservoired fields on the northeast flank. Exploration in the deep, high pressure compartment has resulted in only limited success due mainly to poorer potential reservoir conditions, more difficult definition of traps and increased drilling expenses and risk.

The acoustic pressure waveform from small unconfined charges of plastic explosive

Abstract: The pressure waveform has been measured at distances to 1000 m from 125‐g and 1‐kg unconfined charges of plastic explosive. Pressure waveforms in free air have been compared with other published data and TNT equivalence factors for PE4 are given. Propagation over concrete and water are shown to yield similar waveforms, although the yield factor of the charge appears to be somewhat less over water. Propagation over grass gives waveforms of quite a different character, with much of the high‐frequency content being removed. The positive peak overpressure decays more rapidly with distance than it does over concrete. ANSI Standard S2.20‐1983 is shown to be more suitable for predicting the peak overpressure over concrete or water than over grass. The sound exposure level (SEL) is calculated and empirical expressions are given in terms of charge size, distance, and surface. The effects of C‐weighting are considered, and it is concluded that errors in the application of empirical equations are likely to be increased because of the effects of scaling on the frequency content.

Process for filtering solid-liquid mixtures within an enclosed pressure space

Abstract: The invention relates to a process for the separation, in particular filtration of liquids and solids from solid-liquid mixtures, such as from a mineral, ore, coal or sludge suspensions of contaminated earth. The processing space of the filtration apparatus is submitted to overpressure and includes a collector container for solid-liquid mixture, a pressure filter, a discharge system and container for condensate and solid matter. The separation or filtration takes place at an overpressure and at an elevated temperature, preferably 40° C. to 300° C., conveniently 60° C. to 200° C., preferably about 150° C. The pressure filter device communicates with a source for a heated medium.

Semiconductor type differential pressure measurement apparatus and method for manufacturing the same

Abstract: A semiconductor type differential pressure measurement apparatus is disclosed comprising a measuring diaphragm having its periphery fixed, and two measuring chambers, each having a predetermined spacing along both surfaces of the measuring diaphragm, and which detects differential pressure within allowable limits of measurement. When an overpressure is applied, the diaphragm is stopped by a wall of a measuring chamber to prevent the diaphragm from being damaged by overpressure, so that no additional mechanism is required to prevent damage from overpressure. One embodiment utilizes an additional chamber and overhang to reduce overpressure. Another embodiment utilizes a measuring chamber having the two sides of the diaphragm exposed to the ambient to eliminate need for a pressure resistant casing. In a further embodiment, injected impurities serve as a terminal.

Method and apparatus for injecting liquid into a capillary tube

Abstract: In a method and a corresponding apparatus for injecting liquid from a vial into a capillary tube, in particular in capillary electrophoresis, a source of overpressure and a source of underpressure are connectable to the vial for applying overpressure or underpressure in the space above the liquid. During an injection, the pressure is continuously varied in a controlled way by corresponding control of the pressure sources, for example by controlling associated valves. The pressure is first gradually increased and then gradually decreased. The actual pressure variation during an injection is measured by a pressure sensor and used by a controller to control the durations of the time intervals during which overpressure or underpressure are applied such that a desired amount of liquid is introduced into the capillary.

A Parametric Investigation of Muzzle Blast

Abstract: : Weapons that vary greatly in their bore lengths are fired over a wide range of projectile velocities. Pressure transducers are located from 15 to 400 calibers from the muzzle and at 30-degree increments around the gun. The investigation yields a detailed picture of the flow field, as displayed by overpressure traces. Comparisons of the overpressure data with an older established prediction method show better agreement for the measured points nearer to the muzzle. Here, a scaling approach combined with a parametric least squares investigation is used to model the peak overpressure, which asymptotically approaches the far field behavior yet gives the nonlinear behavior nearer the muzzle. Using the shock wave expression, which depends on the fitted peak overpressure results, an expression for the time of arrival is obtained which in turn is fitted to the time of arrival data. The positive phase duration is then obtained by subtracting the time of arrival from the zero pressure point of the wave, which is traveling at the approximate speed of sound. The shape of the positive phase of the wave is then assumed to correspond to a Friedlander wave. Assuming the shape, an expression for the impulse of the positive phase is obtained that depends on the fitted peak overpressure and the value of the positive phase duration. The parameters describing the positive phase duration are then fitted by using the impulse data. In summation, the physics of the blast wave is used to construct the time of arrival, positive phase duration, and impulse models. Fluid dynamics, Impulse noise, Muzzle blast, Noise management, Overpressure.

Identifying potential gas accumulation sites from Oligocene overpressure data in the Qiongdongnan basin, offshore South China

Abstract: Overpressure in Oligocene formations in southern Qiongdongnan basin, offshore China, can be determined either by actual measurements in wells or by calculations using data derived from well logs and seismic surveys. The overpressure is mainly the result of undercompaction of Oligocene rocks during rapid loading by Pliocene and Quaternary sedimentation and of the subsequent thermal expansion of fluids in the Oligocene strata. Every formation possesses its own normal compaction trend (plot of shale-interval acoustic transit times vs. depth). The actual fluid pressures and potential pressures can be computed by the equilibrium-depth method. This method must be corrected for the thermal expansion of fluid. The pressure corrections are based on shale-interval transit times from well logs, interval velocities interpreted from vertical seismic profile (VSP) surveys, and stacking velocity from sonic log data of nearby wells. Gas generated from source rocks is assumed to have moved vertically from strata of higher hydraulic pressure potential to those of lower potentials and to have moved laterally and accumulated within areas where the contour closures of a gas equipotential hydraulic-pressure surface (U curves) have lower values. In the study area, the vicinity of the Yacheng gas field, the potential maps (U, gas, and V, water, maps) and hydraulic head profiles can be plotted from values derived either from actual pressure measurements or from calculations. These maps and profiles show prospective areas of gas accumulation.

Excessive pressure release valve for packaging container and method for its production

Abstract: PURPOSE: To improve reliability of an overpressure valve including a diaphragm to discharge gas from a packed product by designing the valve in such a manner that the diaphragm is adhered to the container wall through a wedge-shaped adhesive layer, and a center area is defined at the front end side of the wedged part to close a discharge hole. CONSTITUTION: Holes 4..., like a needle-stuck hole, are bored at a flat wall 3 of an air-tight bag 2, and an overpressure valve 1 is provided at the holes 4. The overpressure valve 1 is provided with a square-shaped diaphragm 10 made of a transparent and elastic sheet material, and the diaphragm 10 is adhered to the wall 3 through strip-shaped adhesive layers 11, 12. The adhesive layers 11, 12 have two parallel edge areas 13, 14 and a no-adhesive center area 15 placed between them, and the center area 15 covers the holes 4. The adhesive layers 11, 12 are wedge-shaped and a top edge part 18 limits the no-adhesive center area 15. When overpressure occurs, the center area 15 is bent outward to release the pressure.

Mitigation of Shock Waves in a Cylindrical Tunnel by Foam

Abstract: : This study investigated the effectiveness of foam linings in mitigating shock waves in tunnels. A polyurethane foam liner of varying density, crush strength and thickness was modeled inside a 1 meter radius tunnel and an explosion of 1.25 kg of plastic explosive was simulated. Using CTH, an Eulerian- Lagrangian hydrodynamics code from Sandia National Laboratories, the overpressures were computed and compared graphically to determine the effect of varying each foam parameter. The walls of the tunnel consisted of a perfectly reflecting boundary, and in some cases, a foam liner. Low density foam provided the most shock attenuation. with a 20 cm thick layer of 90% void (0. 1265 g/cm3) foam reducing the shock overpressure by 70% at 50 meters. The effects of foam thickness on the shock pressure varied with the distance from the explosion. The thicker foams raised the initial pressure near the explosion due to constriction of the tunnel area. However, the thicker layers reduced the shock faster. Varying the crush strength of the foam from 1 atm to 3 atm overpressure did not affect its ability to mitigate shock propagation in the tunnel. The results of this study strongly suggest that foam can mitigate shock waves significantly.... Shock, Shock mitigation, Foam, Explosions.

Overpressure eddy reactor - has lower connection at cylindrical vessel for the eddy jet which forms a closed circuit with the lower outlet

Abstract: The cylindrical vessel of the overpressure eddy reactor, to clean sewage soiled by organic matter, has an upper outlet connection for the activated mixt. and the foam disperser,. At the lower end there is a connection to empty the cylinder and allow a closed circuit to be formed for the mixture. The entry inlet connection at the lower end of the cylinder, gives a tangential inflow, which can be connected to the lower outlet to form the closed circuit and also give the insertion of the special eddy jet into the cylinder vessel. The eddy jet is pref. in two tubes, within each other. The outer tube with the compressed air connection, is welded to the jet head. The inner tube, with the connection for the sewage and return foam mixture, opens into the mixing zone in the jet head where the bacteria agglomerates and air bubbles are reduced. The mixt. is forced from the mixing zone by pressure pumps and compressed air at a tangent into the cylindrical vessel, which keeps the matter rotating. The function of the reactor is based on an overpressure. ADVANTAGE - The appts. gives a high O2 delivery and breathing activity, with min. energy requirements and space for the assembly, for universal application in relation to reaction and vols.

Observations and Inferences for Overpressure Development under Salt Sheets in the Gulf of Mexico

Abstract: Four wells in the offshore Gulf of Mexico have penetrated through four different salt sheets and into underlying formations. Interpretations of sonic and density logs, together with mud weight variations, imply highly overpressured regimes below each of the four salt sheets. Models of the development with time of sediments and salt sheets are presented to show the estimates of timing and magnitude of this build-up of overpressure. Investigations are given of both horizontal and tilted sand sheets, together with sheets having a sub-salt thief sand, to provide estimates of (a) thermal focusing by the highly conductive salt; (b) timing and magnitude of pressure build-up and bleed off in formations underlying the impermeable salt sheet; (c) porosity retention by formations below the salt. Importance of salt sheets as an impermeable seal for hydrocarbon retention, and high porosity due to overpressure development, make the subject matter of significance to exploration assessments in the Gulf of Mexico3.

Amplification of Shock Overpressure by Reflection within Concave Corners

Abstract: : In this study, CTH, a production hydrodynamics code developed and provided by Sandia National Laboratories. modeled the interaction of a shock wave with tall V-shaped buildings with various wall lengths and vertex angles. The purpose of this study was to determine the degree to which the length and vertex angle affect the peak overpressure at the vertex. CTH performed two- dimensional Eulerian-Lagrangian computations to obtain solutions of this problem. The models were cast in two-dimensional rectangular geometry on a horizontal plane because of the computational costs of three-dimensional calculations. This geometry simulates tall buildings exposed to a tall Mach stem blast. The free-field shock increased sharply to a peak overpressure of 6.2 psi and returned to ambient conditions after about one second. This incident shock amplified significantly in the building vertices. Peak overpressures measured as high as 8.7 times the incident free-field overpressure of 6.2 psi, or 3.9 times the peak reflected overpressure of 14 psi due to reflection at normal incidence. The amplification was greatest with narrow vertex angles, but was significant (2.7 times that at normal incidence) even with right-angle vertices. The amplification of the peak overpressure due to reflection within concave corners is important in determining the vulnerability of structures to blast damage.... Blast, Blast Amplification, Blast damage, Blast reflection, Shock amplification and Shock reflection.

Electrical switching installation

Abstract: In the case of a gas-insulated medium-voltage switching installation which is formed from a plurality of switch panels (1, 2, 3), a passage from the individual switch panels into a common expansion channel (8) is opened by overpressure as a consequence of an arcing defect. This is predicated on a relatively high pressure response level, for which the encapsulation of the individual switch panels must be designed. The invention now places an expansion vessel (19) into this exhaust path, which expansion vessel (19) compensates for virtually all the pressure fluctuations below the arc response pressure in order to be able to implement installation encapsulation which can be designed for the minimum possible overpressure.

Outline of the Central North Sea overpressured zone based on chalk velocities

Abstract: Due to overpressure below the Upper Miocene in the North Sea, seismic velocities below this level are low relative to depth in the central North Sea. The pronounced increase of chalk velocities with depth makes it possible to use deviations in velocities from a normal velocity-depth trend to outline the areal extent of overpressure in the tentral North Sea.

Spray can filled with a propellant

Abstract: 2.1 Due to the known environmental problems, harmless propellent gases are used more and more in this respect, which however often have the disadvantage that they are combustible. In this case, it can be dangerous if, in the case of overpressure occurring, these propellent gases escape from the spray can simultaneously and completely. The object of the invention is therefore to provide a spray can which opens in the case of a defined overpressure and closes again when said overpressure drops. 2.2 For this purpose, provision is made for a valve plate (1) of the spray can to be provided with apertures (3) which are sealed gas-tightly by closure means under operational pressure and are opened in the case of a defined overpressure. 2.3 It is achieved with the aid of the invention that, on occurrence of a critical overpressure, only a certain amount of the contents is let off from the spray can until said overpressure has been reduced.

Machine for thermally treating objects by heated gaseous medium - has duct, divided into overpressure and low pressure paths, with adjustable wall sections

Abstract: The machine has recirculation and guiding members through which circulates the hot medium transversely in a duct. The duct is divided into an overpressure (8) and an vacuum path (10) both by the recirculation member (6) for the medium and the work (3). It has adjustable wall sections (11) on opposite sides of the work. The sections are for selective coupling of the work to the overpressure or underpressure paths. USE/ADVANTAGE - For hot air drives etc, with selective hot air passage through the work.

The Use of Structural-Acoustic Reciprocity Techniques To Assess Potential Environmental (Structural) Damage From Sonic Booms.

Abstract: : The potential environmental impact of supersonic operations includes damage to conventional and unconventional structures by sonic boom overpressures. The assessment of such damage requires dedicated flyovers for each site at great expense. We show that structural-acoustic techniques may be used to help provide such assessments in their absence. Tests are described whereby transfer functions relating structural response to sonic boom overpressure may be obtained using a stationary acoustic source and appropriate data processing to substitute for the boom. Further structural-acoustic reciprocity is invoked allowing these transfer functions to be determined by measuring the sound radiated by the structure when driven mechanically. Additionally, it is demonstrated that state-of-the-art general purpose computer codes now provide a powerful tool for predicting these transfer functions for complex site geometries and constructions. (MM)

Valved closure cap.

Abstract: of EP0524882The invention provides a closure cap intended particularly for a filling neck of a motor vehicle radiator of the type comprising an overpressure valve (34) which is opened when the force which is applied to its control element (48) by the pressure prevailing inside the cooling circuit of the engine of the vehicle is greater than a predetermined value which is a function of a calibration value of a member for returning the overpressure valve (34) to the closed position, which return member, in accordance with the teachings of the invention, is produced in the form of a gas spring made of a cylinder (38, 42) inside which there is slidingly mounted a control piston (44) whose end radial face (48) interacts with an overpressure valve seat (26).

Safety valve for tyre overpressure

Abstract: The utility model relates to a safety valve for tyre overpressure, which comprises a top rod, an air mouth, a sealing head seat, a sealing assembly, a pressure adjusting bolt and a spring, wherein, the spring is arranged between the sealing assembly and the top rod. The utility model has the technical proposal that the top rod is slightly lengthened, and the spring is adopted for connecting the sealing assembly and the bolt. The utility model can automatically decompress for eliminating the accident hidden danger of tyre overpressure running, and adds a safety measure for motor vehicles.

Ground motion and air overpressure study at the Naval Surface Warfare Center, Crane, Indiana

Abstract: : This report provides documentation for and presents an analysis of a seismic attenuation and air overpressure study at the Naval Surface Warfare Center, Crane, Indiana. The investigation consisted of measuring peak particle velocities and peak air overpressures along two radials (N40 deg E and S40 deg W. Each radial consisted of four to five monitoring stations recording vertical, radial, and transverse ground motions in addition to air overpressures. Data were recorded from 24 August through 5 September 1992, with 3084 time histories being recorded. From the data, ground motion and air overpressure attenuation curves were developed from which predictions could be made given the size of the explosion and the distance from the explosion. Based on the results obtained, the following attenuation curves are proposed. Air overpressure, Peak particle velocity, Ground motions, Regression.

Cavitation‐induced seismic events caused by small explosions in boreholes

Abstract: An electrolytically recharged sleeve exploder was fired at depths between 15.2 m and 51.8 m in a 200-mm diameter, steel‐cased, water‐filled shallow borehole in Hopkins County, Texas. Oxy‐hydrogen explosive gas charges were varied between 30 and 170 kJ. Seismic traces revealed three distinct, delayed, anomalous arrivals. Two of these moved out nonlinearly with increasing charge. The fact that the anomalies were not peculiar to gaseous sleeve explosions was confirmed by repeating part of the experiment using small high explosive charges. The anomalies appear to stem from the collapse of cavities that are created by shock waves. A model is advanced, in which up‐ and downgoing shock fronts sweep away from the explosion at the tube wave velocity. They reflect from the free and plugged ends of the borehole. Reflection at the free end transforms an upgoing overpressure into a downgoing rarefaction. Momentum transfer surges the fluid. Surges accumulate. Two rarefaction shocks eventually collide at the shot point....