Vacuum-pump selection should begin with the required working pressure and the actual process conditions. The following factors help match a pump or pump combination to the application.
- The pump's ultimate pressure should be sufficiently lower than the equipment's working pressure. A margin of half to one order of magnitude is commonly used.
- Choose a working point inside the pump's stable operating range; do not keep the pump at the edge of its pressure range for long periods.
- At the required working pressure, the pump must remove all gas generated by the process.
- Combine pump types when one pump cannot meet the full requirement. Some pumps need a backing pump or pre-vacuum stage.
- Consider oil contamination requirements. Oil-free processes may require water-ring, adsorption, ion or cryogenic pump solutions.
- Understand the pumped gas, including condensable vapour, dust and corrosive components, and add condensers or filters when needed.
- Evaluate whether exhaust oil vapour could affect the environment; use an oil-free pump or route exhaust outdoors where appropriate.
- Check whether vibration could affect the process or surrounding equipment and use isolation measures if necessary.
- Compare purchase price together with long-term operating and maintenance cost.