GB514767A - Improvements in high vacuum condensation or diffusion pumps - Google Patents

Abstract

514,767. Diffusion pumps. EASTMAN KODAK CO. May 14, 1938, No. 22258/39. Convention date, May 18, 1937. Divided out of 514,749. [Class 71] A cascade diffusion pump which is operated by an organic fluid which may be of a mixed character is constructed to prevent absorption of gases by surfaces exposed to the high degree of vacuum, and so to prevent diffusion of such gases into the space to be evacuated. This is effected in the apparatus shown, in which a main conduit 148 is formed with bent extensions 150, 149 leading respectively to a backing pump and the space to be evacuated, by withdrawing liquid from one end of the boiler 166 by means of a pipe 167, passing it through a cooling coil 168 and then over a series of reentrant rings 153 in the wall of the low-pressure conduit 149 from which it flows by a pipe 154 back to the main reservoir 155. The base of the reservoir 155 is connected to a conduit with an intermittently actuated annular plunger 160 operated by a solenoid 163 and fitted with non-return valves 162, 164 to supply liquid to the boiler 166. Vapour jets of vapour having increasing vapour pressure values emerge between conical surfaces 180, 175, 176, 177, 178, which are fitted with plates 179, 171 to close the ends of the series. Any vapours present in the conduit 149 are absorbed by the liquid passing over the rings 153, and so are returned back to the reservoir 155.