| 摘要 |
PROBLEM TO BE SOLVED: To provide an evacuator high in energy efficiency at the time when pressure on the air intake side is arrival pressure or vacuum to a certain degrees by reducing motive power by differential pressure. SOLUTION: A booster pump A is constituted of a dry pump, a roughing pump B is constituted of a scroll pump and designed exhaust speed of the roughing pump B is made in size enough to function as the roughing pump although it is lower than designed exhaust speed of the booster pump A on the evacuator 100 furnished with the roughing pump B and the booster pump A.
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