GB815070A - Improvements in or relating to vacuum pumping apparatus - Google Patents

Abstract

815,070. Vacuum pumping apparatus. EDWARDS HIGH VACUUM Ltd. Jan. 22, 1957 [Jan. 25, 1956], No. 2530/56. Class 71. A vacuum pumping apparatus comprises a container divided into a process chamber 20 to be evacuated, and a chamber 21 housing flash boiler operated pumps, by a partition 23 having a large throat aperture 24. A cooling tube 22 surrounds the wall of that part of the container housing the pumps to provide a condensing surface for the pumps and the throat 24 may be outwardly flared as at 25 to form an annular pumping space, the flared portion 25 also being cooled. An outlet duct 29 leads from the pumping space to a further flash boiler operated pump 30 which is connected by a pipe 31 to a suitable Fore-pump. The flash boiler operated pumps have flash boilers 27 and vapour nozzles 26 and may be of the type described in Specification 586,516. Such an arrangement of apparatus provides direct access between the process chamber and pump without the normal duct, traps, valves &c., between these parts and when it is required to remove or replace articles in the process chamber it is merely necessary to interrupt the operation of the flash boilers. In a modified form the pump is positioned below the process chamber communication between the two being by an annular aperture. In such an arrangement the further pump 30 may be positioned in the container. The Provisional Specification describes also an arrangement for housing a diffusion pump in the container with a valve plate which may be moved across the aperture between the two chambers. The diffusion pump may be of the type described in Specification 806,788.