Two-stage vacuum pump, to extract air/process gas from a vessel, has a cold gas feed to the rotary piston pump to prevent thermal expansion and sticking at the screw pump

摘要

The two-stage vacuum pump, to evacuate a vessel rapidly to extract air or process gases, has a rotary piston pump (1) and a screw pump (2) behind each other. To start pumping with both pumps, the rotary piston pump is cooled, by a cold gas through a feed channel (12) with a cooler (13) into the outlet of the rotary piston pump.