6. Vacuum measurement in practice

As with any measurement problem, clearly defining the measurand is the most important operation. In the case of vacuum measurement, this involves locating the area of the installation where the pressure is to be measured, and knowing which gas is present in the installation. The next step is to define the uncertainty of the measurand, which will determine the equipment to be used (in particular the instrumentation) to achieve this objective.

A few measurement examples are presented in this chapter, which is by no means exhaustive of the variety of situations that can be encountered. A qualitative analysis of uncertainty according to measurement configuration is then proposed.