| 摘要 |
<p>The present invention discloses an evacuation apparatus for evacuating a tank, a chamber, and the like; wherein a mechanical vacuum booster pump is provided at an up-stream side of an exterior side vacuum pump; wherein the mechanical booster pump has discharge openings for low compression and a discharge opening for discharging a high compression gas; wherein, in case when the exterior side vacuum pump starts discharging a gas, the gas is sent to the exterior side vacuum pump through all of the discharge openings for low compression and the discharge opening for discharging a high compression gas and, in case when the discharged gas pressure reaches afterward an ultimate pressure (a medium vacuum) attainable by the exterior side vacuum pump, the gas is sent to the exterior side vacuum pump only through the discharge opening for discharging a high compression gas.</p> |
