blower — To achieve a higher vacuum, various techniques can be used like using multiple vacuum pumps in series. A partial vacuum, or rough vacuum, can be created using a blower that transports a gas load from an inlet port to an outlet (exhaust) port. Usually followed by a different pump used to achieve the higher vacuum.

References: Wikipedia, the free encyclopedia – http://en.wikipedia.org/w/index.php?title=Vacuum_pump