Pressure measurement procedure

The pressure measurment and fluid sampling procedures can be repealed at multiple depths in the reservoir. 

Analytical Procedures. Oxygen difluoride may be determined conveniently by quantitative appHcation of k, nmr, and mass spectroscopy. Purity may also be assessed by vapor pressure measurements. Wet-chemical analyses can be conducted either by digestion with excess NaOH, followed by measurement of the excess base (2) and the fluoride ion (48,49), or by reaction with acidified KI solution, followed by measurement of the Hberated I2 (4). 

Gas flows are often determined by measuring the associated pressures. Figure 32-4 illustrates several different pressure measurements commonly made on systems carrying gases. Static pressure measurements are made to adjust the absolute pressure to standard conditions specified in the test procedure. 

Characterization of the cavitational phenomena and its effects in sonochemical reactors are generally described through mapping. Mapping of sonochemical reactor is a stepwise procedure where cavitational activity can be quantified by means of primary effect (temperature or pressure measurement at the time of bubble collapse) and/or secondary effect (quantification of chemical or physical effects in terms of measurable quantities after the bubble collapse) to identify the active and passive zones. 

The possibility of automatic collection and evaluation of thermoanalytical data should be mentioned here in connection with the thermogravimetric vapor pressure measurements. Principally, any desired quantitative evaluation procedure in thermal... 

Values for the parameters are determined by a least squares fit of experimental data using eq (5) for experiments such as galvanic cells measurements that measure solute activity and thus y/Yref values, and eq (6) for experiments such as vapor pressure measurements that measure solvent activity and thus (f) values. All the original data are used in a single fitting program to determine the best values for the parameters. A detailed description of the evaluation procedure has been illustrated for the system calcium chloride-water (Staples and Nuttall, 1977), and calculations deriving activity data from a variety of experimental technique measurements have also been described. 

Detonation, Chapman- auguet Pressure Measurements. See under Detonation (and Explosion), Experimental Procedures and also paper by W.E. Deal, JChemPhys 27, 796-800(1957)... 

The method of determination of virial coefficients by GC consists of measuring the retention volumes at various carrier gas pressures and extrapolating to zero pressure. Three procedures of extrapolation have been suggested, although they do not give the same results. The method of Cruickshank, Windsor, and Young (30), which takes into account carrier gas flowrate and local pressure, seems to be most promising. 

Kinetics. Kinetic measurements were made by following CO uptake at constant pressure using the apparatus and procedure described earlier (17). The Ru catalyst concentration used was in the range (0.6-6.0) X 10 2A/. Total pressures up to 1 atm and CO partial pressures from 55-590 mm were used. The CO solubility in pure piperidine was 6.5 X 10"3M atm 1 at 21 °C and 5.8 X 10 3M atm 1 at 75°C, Henry s law being obeyed at least up to 1 atm the solubility in toluene was similar (5.7 X 10"3M atm"1 at both 21° and 75°C). The solubility in a toluene-piperidine mixture (1 1 by vol), 5.5 X 10"3Af atm 1 at 75°C was only slightly less than those in the pure solvents. The vapor pressures of piperidine and toluene differ by only about 15-20 mm between 50°-75°C, that of piperidine being the greater (18). Vapor pressure measurements on the solvent mixtures showed that Raoult s Law was obeyed approximately, and the partial CO pressures over toluene-piperidine solutions could be readily estimated. For practical purposes, the partial pressure of piperidine-toluene mixtures, 2.0-10.1M (neat) in piperidine could be taken as that of pure piperidine. 

The apparatus and procedure described require great care in setting up and in operation. The effort is eased considerably if an automatic pressure measuring device operating at effectively constant volume is used instead of the manometer9. Probably, all apparatus now has some form of pressure transducer. Improvements as regards accuracy and sensitivity can also be obtained by, for example, having a vacuum instead of atmospheric pressure on the low pressure side. 

Left ventricular pressure measurements are monitored continuously by use of a 5F end-hole pig-tail catheter in the left ventricular apex and a 6F femoral sheath in order to be able to assess the gradient, If the outflow gradient is absent or small under the basal conditions, the magnitude of provocable obstruction is most appropriately assessed with maneuvers (Valsalva, ventricular pacing, extrasystoles, physiological exercise, amyl nitrate), The inability to elicit any provocable gradient is a contraindication to the procedure,... 

For laboratory-scale modification, distinction has to be made between static and dynamic adsorption procedures. In a static procedure, the substrate is contacted with a known volume of gas at a well-defined pressure. The modifying gas may be stationary or circulating in a closed loop. Modification in a static gas adsorption apparatus allows the careful control of all reaction parameters. Temperature and pressure can be controlled and easily measured. Adsorption kinetics may be determined by following the pressure as a function of the reaction time. Figure 8.13 displays a volumetric adsorption apparatus, in which mercury is used, as a means to change the internal volume and for pressure measurement. 

There are two general procedures for pressure measurement direct and indirect. 

The additional samples for materials distribution, temperature measurements, and pressure measurements followed the identical procedure and employed exactly the same sampling grid. 

Clearance procedures can be conducted in all laboratory animal species anesthetized and conscious animal models may be used. Measurement of arterial pressure is advisable, especially in anesthetized preparations, to insure that renal perfusion pressure remains within the autoregulatory range (usually 80-120 mmHg). Vascular access ports can be helpful to provide continuous arterial access for pressure measurements (Mann et al. 1987). 

Mandavilli U, Schmidt J, Rattner DW et al. (1991) Continuous complete collection of uncontaminated urine from consdous rodents. Laboratory Animal Science 41 258-261 Mann WA, Landi MS, Homer E et al. (1987) A simple procedure for direct blood pressure measurements in conscious dogs. Lab Animal Sci 37(1) 105—108 Newman DJ, Price CP (1999) Renal function and nitrogen metabolites. In Burtis CA, Ashwood ER (eds) Tietz Textbook of Clinical Chemistry, 3rd edn. W.B. Saunders Company, Philadelphia, pp 1204-1270 Pitts RF (1968) Physiology of the Kidney and Body Fluids, 2nd edn. YearBook Medical Publishers Inc, Chicago Ragan HA, Weller RE (1999) Markers of renal function and injury. In Loeb WF, Quimby FW (eds) The Clinical Chemistry of Laboratory Animals, 2nd edn. Taylor and Francis, Philadelphia, pp 519-548... 

The anesthetics are introduced from conventional vaporizers. For the determination of MAC, an initial concentration is used that permits movement of the rats in response to noxious stimulation. A tail clamp is applied for 1 minor until the animal moves, and the anesthetic partial pressure is measured by gas chromatography. If the animal moves, the partial pressure is increased by 0.2% or 0.3% atmospheres. After equilibration for 30 min, the tail clamp is applied again and the anesthetic partial pressure measured by gas chromatography. This procedure is repeated until the partial pressures bracketing movement-nonmovement are determined for each rat. 

To determinate the freezing point under gas pressure the cell is filled with melt of known composition. Then the wanted pressure is adjusted with the used gas. The measuring procedure is started when the phase equilibrium between melt and gas phase at a temperature tight upon expected freezing point is reached. 

Several vapor pressure osmometers are now commercially available. Although they are mainly used for determining number-average molecular weights in aqueous and organic solvents, they can also be employed to evaluate the total osmolality of biological solutions or dissociation and activity coefficients. Each model has its own technical characteristics. However, all are comparable in terms of general measurement procedure and sensitivity. 

The technique of capillary pressure measurement involves the following procedure the solution is poured into a Teflon bath (in order to ensure a strictly horizontal plane of the liquid) the glass tube is inserted vertically into the solution (Fig. 2.7) then the distance between the solution surface and the lowest point of the meniscus in the tube. The technique allows to measure pa with an accuracy of + 0.1 Pa. 

Droperidol is used as an adjunct in conscious sedation for endoscopic procedures. In one study, basal biliary sphincter pressures measured in 35 patients before and after droperidol were 56 and 48 mmHg the basal pancreatic sphincter pressures measured in 22 patients before and after droperidol were 92 and 67 mmHg (24). However, in another study basal pressures of the biliary sphincter and of the pancreatic sphincter were not significantly altered by droperidol (25). 

Finally, repeat the complete procedure with Ar as the second gas. In addition to determining the diffusion coefficients at atmospheric pressure, measure one of them at half an atmosphere. 

Vapor Pressure Measurements. Total vapor pressures were measured at 30°C with a Texas Instruments quartz spiral gauge. The procedure used was similar to that given previously (5). The concentration of water after the experiment was checked by Karl Fischer titration, while that of ether was found by weighing the cell before and after the vapor pressure determination the loss of weight was that of ether. Since Sb( V) interferes with the Karl Fischer titration of water, the water concentration in the HSbClG solutions was also obtained from the loss of weight of the cell. 

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