Pressure measuring systems

A typical tire-pressure measurement system is shown in Fig. 7.20.1. 

Fig. 7.20.2 shows the components of the tire pressure measurement system. 

With intravascular blood pressure measuring systems, the liquid coupling between the blood and the pressure transducer is eliminated by incorporating the sensor into the tip of a catheter that is placed in the vascular system [18]. 

A number of pressure-measuring systems have been used in liquid metals with varying degrees of success. The tendency of oxides and insolubles to migrate to cold zones, plus the difficulty in keeping long lines at uniform temperatures, make the direct application of Bourdon-type pressure gages difficult. 

Figure 4.4.17. Description of the principal construction of a Knauer membrane osmometer A 300 1 - head thermostat, 2 - channel for syringe, 3 - calibration device with suction tube, 4 - calibration glass, 5 - c illary position MEASUREMENT, 6 - capillary position CALIBRATION, 7 - tension screws, 8 - cell retaining disc, 9 - upper half of measuring cell, 10 - sample introduction system, 11 -semipermeable membrane, 12 - lower half of measuring cell, 13 -pressure measuring system, 14 - cell thermostat, 15 - suction of calibration bottle. [Reprinted from the operating manual with permission from Dr. H. Knauer GmbH (Germany)].

Song, S.-Y., and Lee, J.W. A Detonation Pressure Measurement System Employing High Resistance Manganin Foil Gauge, 9th Symposium (Inter-national) on Detonation, Portland, OR, 1989, pp. 226-232. 

Kumar B, Das A, Alagirusamy R. Study on interface pressure generated by a bandage using in vitro pressure measurement system. J Text Inst 2013 104(12) 1374—83. 

As of 2011, pressure-measurement systems are stiU too expensive to allow sufficient numbers to be deployed to report pressure with enough spatial and time resolution to permit development of a real-time three-dimensional representation. Research in this area will doubtless improve the resolution and response and hopefully bring down the cost. With more pressure sensors distributed over the world, weather prediction will become more accurate and reliable. 

Figures 11.7a-11.7d show experimental results at four different instances, obtained using the Tekscan distributed pressure measurement system. Figure 11.7e and 11.7f show the corresponding numerical results obtained using SimLCM, the LCM simulation code developed at the University of Auckland. The comparison is excellent, with the numerical simulation slightly underestimating the peak stresses. Since the final volume fraction here is quite low, the total compaction stresses is dominated by the fluid pressures. Figure 11.8a-11.8d and 11.8e and 11.8f are analogous to those of Fig. 11.7. Here, the stresses are very large because of the relatively large fibre volume fractions reached at the end of wet compression. For this case the total stresses are now dominated by the reinforcement compaction stress.

Pressure transducers are often preferred when high-accuracy measurements on a broad range of materials are required. Force transducers see use in quality control labs, where ease of operation and cleaning are important, or when maximum corrosion resistance is desired. Further discussions will assume that a pressure measurement system rather than a force transducer is used. (To calculate stress, the force measurement is converted into a barrel pressure by dividing by the cross-sectional area of the barrel, so no generality is lost.)... 

The simple constant-volume gas thermometer depicted in Fig. 2.6 on the next page uses a mercury manometer to measure the pressure. More sophisticated versions have a diaphragm pressure transducer between the bulb and the pressure measurement system. 

The principles of measurements with a gas thermometer are simple, but in practice great care is needed to obtain adequate precision and accuracy. Corrections or precautions are required for such sources of error as thermal expansion of the gas hulh, dead volume between the bulb and pressure measurement system, adsorption of the thermometric gas on interior surfaces, and desorption of surface contaminants. 

To measure the permeation of a gas, the apparatus usually consists of a sample holder, a gas supplying system, a pressure measurement system and a measurement for the flow rate of the gas passed through the sample. A standard test method for determining gas permeability of polymer films is described in ASTM D1434, or DIN 53380. 

Foam pressure measurement systems are also used as a criterion to set the demolding time. There are pneumatic and electronic foam pressure measurement systems. 

Contact pressure measuring system by Blazek and Schultz-Ehrenburg, introduced in 1997. 

Novel-pliance pressure measuring system, available since the 1990s in different layouts. 

Kikuhime pressure measuring system, developed at the end of the 1990s at the Technical College Hokkaido, Japan. 

The critical factor in the design, construction, and operation of a deodorizer will, however, be the flavor of the oil it produces. Air leaks bad enough to influence the flavor of the oil are frequently so small that they cannot be detected by the system s pressure-measuring systems, and reliance is normally placed on oil tasting. Normal deodorization practice to preserve the quality of the oil includes adding 0.005-0.01% of citric acid to the freshly deodorized oil to deactivate any metals present. This addition is frequently carried out as soon as the oil temperature falls below 300°F (150°C) to prevent decomposition of the citric acid. Where legally allowed and relevant to the final use of the oil, antioxidants such as TBHQ and natural tocopherols may be added to the freshly deodorized oil to enhance its stability. 

H. Vaugh, The Response Characteristics of Airplane and Missile Pressure Measuring Systems, Sandia Corporation, Report No. 174-54-51, 1954. 

A2.2 Pressure Gage—The pressure measuring system shall be a Bourdon type spring gage as described in A 1.2 or a suitable pressure transducer and digital readout. The pressure measuring system shall be remotely mounted from the vapor pressure apparatus and terminations provided for use of a quick connection type fitting. 

The pressure transducer shall have a minimum operational range from 0 to 177 kPa (0 to 25.7 psi) with a minimum resolution of 0.1 kPa (0.01 psi) and a minimum accuracy of 0.8 kPa ( 0.12 psi). The pressure measurement system shall include assodat electronics and readout devices to display the resulting pressure reading. 

As a general feature of most osmometers, the membrane is clamped into a stainless steel thermostated chamber (the measuring cell and the pressure measuring system of modem osmometers are built into a high-grade electronically stabilized thermostat) and serves as barrier between the pure solvent and the polymer solution sides of the chamber. The solvent side (bottom) is in juxtaposition with a pressure sensor, e.g., the diaphragm of a capacitance strain gauge or a piezo-chip. The solvent transport is measured across the... 

Oliveira, C.C., Sepulveda, A.T., Ahneida, N., Wardle, B.L., da SUva, J.M., Rocha, L.A., 2015. Implantable flexible pressure measurement system based on inductive coupling. IEEE Trans. Biomed. Eng. 62 (2), 680-687. [Internet]. Available from http //ieeexplore.ieee. org/lpdocs/epic03/wrapper.htm amumber=6933941. 

Figure 1 Schematic of experimental setup, (a) quartz microbalance (b) vacuum chamber (c) gas dosing system (d) pressure measurement system (e) vacuum jacket (f) thermal link, including heater and thermometer (g) oscillator circuit.

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