**Related Resources: fluid flow**

### Vacuum Pumping Speed per. ISO 21360-1 Formulas

**Fluid Dynamics Vacuum Engineering and Design**

**Vacuum Pumping Speed per. ISO 21360-1 Formulas**

Vacuum pump performance is rated in terms of throughput, pumping speed, and vacuum pressure capability. They are rated for either intermittent or continuous duty. Throughput is the product of volumetric flow rate and pressure. Pumping speed has units of volume/time and is the mean volume flow through the cross section of the inlet port of a vacuum pump. Determination of the pumping speed is described in ISO 21360-1.

Vacuum pump performance curves are plots of pumping speed as a function of inlet pressure. The lowest pressure that can be achieved by a vacuum pump can be calculated using the following calculator and equation:

*p*_{min} = *p*_{0} e^{ ( -Sefft / V )
} ) + Q_{o} / S_{eff} + Q_{D} / S_{eff} + Q_{K} / S_{eff}

Where:

*p*_{min} = deepest vacuum achievable,

*p*_{0} = initial pressure,

t = time,

S_{eff} = effective pumping speed,

V = evacuation volume,

Q_{o} = Outgassing flow rate,

Q_{D} = Diffusion flow rate,

Q_{K} = Permeation flow rate

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References:

- Karl Jousten (Hrsg.), Wutz Handbuch Vakuumtechnik,
- Pupp / Hartmann, Vakuumtechnik Carl Hanser Verlag
- Schweitzer, Bleuler, Traxler, Active Magnetic Bearings, Hochschulverlag AG an der ETH Zürich
- Fremerey, Vacuum 32 (1982) S.
- Hobson und Redhead, Can. J. Phys. 36 (1958)
- Redhead, Electron Stimulated Desorption, Vacuum 12 (1962)
- Dawson, Quadrupol Mass Spectrometry, Elsevier Amsterdam (1976)
- Brubaker, 14th National Symposium, Am. Vac. Soc. (1967)
- Fachbericht Balzers BG 800003 Das Funktionsprinzip des Quadrupol Massenspektrometers. (1990)