Vacuum terms in common use
(1)main pump：In vacuum systems, it is used for obtaining the required vacuum degree to satisfy the definite process. Such as the oil diffusion pump is the main pump which used in the vacuum plating machine.
(2)fore pump：It is used for keeping the fore pressure of a pump is lower than the fore critical pressure. Such as the fore set Rotary pump or Rotary piston pump are also the fore pump.
(3)rough pump：To pump air under the ATM, and make the system pressure to achieve the vacuum pressure that the next pump begins to aspirate. Such as the rotary piston pump in the plating vacuum machine is the rough oil pump.
(4)maintain pump：In vacuum system, when the suction capacity is very small, so the fore pump isn’t used efficiently. Then install a lower volume assistant pump to maintain the main pump’s working.This kind of pump is maintain pump.For example: install a small rotary vane pump at the diffusion vacuum pump’s outlet port.