5.5.1 Rough Vacuum

The pressure range from approximately 10 $^{\textrm{-3}}$- 760 torr is termed rough vacuum. Rough vacuum can be obtained using mechanical pumps, such as rotary vane pumps. High throughput rough vacuum pumps are available, such as the so-called roots blower. Commercial mass spectrometers typically have at least one mechanical vacuum pump and often have more. For example, there may be one pump for each high vacuum pump as well as a roughing pump for inlet valves, etc.