Piston manometer

C, static method-inclined piston manometer, measured range -40 to 10°C, Osborn Douslin... 

The piston manometer is a primary standard gauge that balances the pressure on one arm in a piston-cylinder arrangement by the addition of... 

General Case.—Consider a mass m of a gas enclosed in a cylinder fitted with a piston and in connexion with a manometer capable of indicating very rapid changes of pressure (Fig. 21). Let p0 be the initial pressure. 

For coloured vapours (bromine) an optical method, depending on measuring the refractive index by an interferometer, has been used. Scott used the Langmuir vibrating quartz-fibre manometer ( 14.VII A) for alkali metals. Fouretier, for Small pressures, used a curved tube containing a dishshaped piston with a small clearance, operating a lever moving a mirror. 

Fig. 1.6 A cross section of a 1.6 GPa cylinder (B) to experimental cell, (C) compression chamber (diameter, 16 mm), (H) piston head, (1) inner cylinder under radial compression, (M) to resistance manometer, (P) high-pressure outlet plug with electrical leads, (U) unsupported-area, Bridgman-type, sliding-piston arrangement. The force applied to the piston by the oil ram for a pressure of 1.6 GPa is F= 350 kN.

Usually, the force, F, is generated by the dead weight on a piston with well-defined area. A, as illustrated in Fig. 2.2. Accurate determinations of the effective area, and corrections for friction and for the buoyancy of the piston require great care if the best possible (absolute) accuracies are required (that is, accuracies of the order of 10 p.p.m (parts per million) ). For practical applications, other secondary pressure gauges (manometers) are used they are usually commercially calibrated, or they can be recalibrated, if necessary, by comparison with transfer standards. ... 

An original route is that proposed by Ter-Minassian and Million in 1983 [44] with their pneumatic compensation calorimeter, represented in Fig 10. The tubular sample cell 4 is in good thermal contact with four metallic bulbs. Two of them operate like bulb 1 in the figure, Le. as pneumatic thermal detectors. They are filled with gas, say around 1 bar, and their pressure is compared, by means of a differential manometer, with the constant pressure of a reference reservoir 3 immersed in the surrounding thermostat block 5. Therefore, they detect any temperature change of the sample. The two oflier bulbs operate like bulb 2, i.e. as pneumatic energy-compensating devices. They are also filled with gas, say around 1 bar, but they are connected to flie piston-cylinder 7 which enables the heat of compression (or decompression) necessary to cancel the temperature difference between the sample and thermostat (as detected with the first set of bulbs) to be produced in the bulb. More recently, Zimmermaim and Keller built a comparable pneumatic compensation calorimeter whose calorimetric performances were carefully examined [45]. 

A working pressure sensor linked via chained calibrations to a standard liquid manometer or piston gauge maintained by an NMI... 

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