Pumps and Pumping Systems

Vacuum pumps, either singly or, more usually, as part of a pumping system, create and maintain the conditions appropriate to a required process. Each of the types of vacuum pump available has a characteristic working range in which it is effective. Outside that range, shortcomings in performance become apparent. 

In this chapter, those pumps that are frequently encountered throughout the range of vacuum pressures are dealt with (see Table 3.1). Where necessary, to support the calculations, the operating principles and pump characteristics are reviewed. With gas-transfer pumps operating in the HV/UHV range (typically diffusion or turbomolecular pumps), continuous operation of backing (forevacuum) pumps is required for efficient performance. In such cases, the combination is considered. 

Important characteristics of vacuum pumps include the ultimate pressure (puu), the inlet pumping speed (Sq) and the variation of the latter with pressure. The type of pump or combination of pumps chosen for an application depends on the gas load to be handled and the base pressure to be achieved in a given time. Other important factors include the cleanliness of the pumping system and, with some systems, the absence or otherwise of vibrations. 

An accepted criterion for cleanliness in a vacuum system depends on analysis of the residual gases it contains. A system is clean if  

Rotary vane/rotary piston pumps 1 -stage, p -10 mbar 2-stage, / ult - 10 3 mbar Dry pumps 

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Turton, R. K. An Introductory Guide to Pumps and Pumping Systems (Mechanical Engineering Publications. London. 1993)... 

Pumps and Pumping Systems Table 3.6 kn values for the Roots pump... 

Mackay, R. Current best reliability and maintenance practices of pumps and pump systems. Results Oriented Reliability Maintenance Conference, Raleigh, N.C., IDCON Inc. November, 2002. 

RISHEL J B (2002) Water Pumps and Pumping Systems. New York McGraw-Hill. 

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