scope:

Describes the techniques for the determination of the rate of leakage across the boundary of an isolated object, subjected to a pressure difference. The techniques are based on the evaluation of the change of the mass of gas within the test object. The ideal gas equation states the relationship between mass, pressure, temperature and volume of the gas contained in the internal free volume of the object. In some circumstances one or more variables may be considered constant and so the mass change can, for example, be assessed by monitoring the pressure or pressure-temperature changes within the test object.