a) Vacuum pumps where – via one or several compression stages – the gas particles are removed from the volume which is to be pumped and ejected into the atmosphere (compression pumps). The gas particles are pumped by means of displacement or pulse transfer.
b) Vacuum pumps where the gas particles which are to be removed condense on or are bonded by other means (e.g. chemically) to a solid surface, which often is part of the boundary forming volume itself.
A classification which is more in line with the state-of-the-art and practical applications makes a difference between the following types of pumps, of which the first three classes belong to the compression pumps and where the two remaining classes belong to the condensation and getter pumps:
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A glossary of symbols commonly used in vacuum technology diagrams as a visual representation of pump types and parts in pumping systems
An overview of measurement units used in vacuum technology and what the symbols stand for, as well as the modern equivalents of historical units
References, sources and further reading related to the fundamental knowledge of vacuum technology