Pfeiffer Vacuum

2.1.5 Pumping speed of pumping stages connected in series

Let us consider a vacuum pump having a pumping speed S0 and a compression ratio K0. The pump has backflow losses through gaps having conductivity LR. Let inlet pressure be p1 and discharge pressure p2. An additional pump having a pumping speed Sv is connected on the outlet side.

The pumping station will displace the following volume of gas:

Formula 2-2:

Pump combination gas flow

Where LR << S0, backflow conductivity LR is:

Formula 2-3:

Backflow conductivity

and the real compression ratio is:

Formula 2-4:

Real compression ratio

Using the above formulas, it therefore follows that the pumping speed S of a two-stage pumping station will be:

Formula 2-5:

Recursion pumping speed

This formula can also be used as the recursion formula for multiple pumping stages that are connected in series by starting with the pumping speed Sv of the last stage and inserting the K0 and S0 of the preceding stage.

Page functions
  • How would you rate this page?


  • Recommend this page!


  • Social Networks:


Contact options

Our points of contact are available to you at any time:

Display contact options


You can use our contact form to send your request or concern directly to us.

Contact Form

Headquarters postal address

Pfeiffer Vacuum GmbH
Berliner Strasse 43
35614 Asslar

P.O. Box

Pfeiffer Vacuum GmbH
Postfach 1280
35608 Asslar

T +49 6441 802-0
F +49 6441 802-1202

Copyright © 2015 Pfeiffer Vacuum GmbH