Vacuum Technology

Capacities >are available from 1/2 to 1,000 cubic feet per minute, operating from atmospheric pressure down to as low as 2 ´ 10-2 torr for single-stage pumps and less than 5 ´ 10-3 torr for two-stage pumps. The pumps develop their full speed from atmosphere to about one torr, the speed then decreasing to zero at their ultimate pressures. One device of this type, useful for pumping both liquids