Survey of the most usual pumping processes

Vacuum technology has undergone rapid development since the Fifties. In research and in most branches of industry today, it is indispensable. 

Generally, the pumping operation for these processes can be divided into two categories - dry- and wet - vacuum procedures, that is, into processes in A/hich no significant amounts of vapor have to be pumped and those in A/hich vapors (mostly water or organic) arise. 

Dry processes work primarily in a narrow and limited pressure region. 

The system is usually evacuated to a suitable characteristic pressure before the actual working process begins. This happens, for example, in plants tor evaporative coating, electron-beam welding, and crystal pulling in particle accelerators, mass spectrometers, electron microscopes and others. 

Further, there are dry processes in w/hich degassing in vacuum is the actual technical process. These include work in induction- and arc furnaces, steel degassing plants, and plants for the manufacture of pure metals and electron tubes. 

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