3. Pumping a volume

Volume pumping refers to the action of lowering the gas pressure in a volume. This is achieved using a vacuum pump. Vacuum pump performance can be adversely affected if unsuitable piping is used between the pump and the enclosure. As far as possible, the pressure drop introduced by the piping should remain negligible. This is one of the parameters to be checked in an installation calculation. In high-vacuum and ultra-high vacuum, calculations and experiments show that the time required to reach the desired pressure is mainly due not to the size of the volume to be pumped, but to the surface area of the desorbing parts.