Compression ratio of turbopumps Definition, calculation, and use of data

 

A compression ratio is generally the ratio of discharge pressure to intake pressure of a pump. For the turbomolecular pumps, in particular, it is the ratio of the pressure measured at the fore-vacuum flange, to the pressure measured on the high vacuum flange.

Defining the compression ratio
The compression ratio is usually determined without any gas throughput inside the pump. This is known as the zero throughput, which is identified by the index “0”. In the literature and the technical data for a turbopump, the compression ratio is therefore usually referred to as K0. The compression ratio of a turbopump is measured in practice by increasing the backing pressure through gradually introducing a gas into the fore-vacuum line while measuring the ensuing high vacuum pressure.

Read more about this state of the art technology in the attached application report.

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