GB836820A - Improvements in or relating to vacuum pipe systems - Google Patents

Abstract

836,820. Liquid ring pumps; rotary pumps. HERAEUS G.m.b.H., W. C. Aug. 3, 1956, [Aug. 16, 1955], No.24036/56. Classes 110 (1) and 110(2). A vacuum pump system comprises a Roots blower and a water-ring pump connected in series, both pumps being driven by a single motor so that the ratio of their speeds remains constant. In the plant shown, a Roots blower vacuum pump 1 is backed by a water-ring pump 2, the two pumps having a common driving motor (not shown). Either a shaft drive or belt drive may be used. A diffusion pump or, as shown, a high-vacuum Roots blower 8, having an evacuated jacket and with the driving motor contained within the casing, may be added. If the space to be evacuated contains dust, a centrifugal or cyclone separator 16 and a coarse separator 14 may be used. A handoperated valve 15 and a magnetic valve 13 may be provided. A magnetic valve 10, closing when the current supply to the motor is interrupted to prevent back flow of water from the water-ring pump 2, and a magnetic valve 9 which opens in the same event to admit scavenging air to the water-ring pump, may be provided. In addition, a non-return valve 7, a magnetic valve in the water supply to the pump 2 and a water thermometer may be provided. Pipe 3 communicates with atmosphere or with a vessel in which water is separated from the air for return to the water-ring pump. Preferably, the pump 1 has a delivery capacity 30 to 70% greater than that of the pump 2.