scope:

The thermodynamic state of a simple fluid is specified by two independent properties. In experiments involving fluids, pressure is customarily selected as one of the properties to be measured. Pressure measurements are also important in systems involving flowing fluids as an indirect means of measuring velocity and flow rate.

Relevant static and dynamic pressures span a range of 1015 to 107 times atmospheric pressure. As such, and because of associated dynamic pressure-measurement problems, pressure-measurement systems vary greatly in complexity and include a large number of different devices.

This Section covers the definition of pressure, fundamental thermodynamic and fluid-mechanic concepts of pressure, pressure units and conversion among different units, pressure considerations in and pressure relations for flowing fluids, and the use of existing installed instrumentation in equipment tests.