| 摘要 |
1,201,213. Diffusion pumps. BENDIX CORP. Jan.30, 1968 [Nov.30, 1967], No.4601/68. Heading F1E. In an oil diffusion pump comprising a boiler 14 and a multi-stage nozzle assembly 27-30 in a cooled casing 12, oleophobic material having a contact angle with the pump oil of 35 degrees or greater, e.g. P.T.F.E., polychloralethylene, or a copolymer of tetrafluoroethylene and hexafluoropropylene, is applied as a coating to the cowl 34 of the first stage nozzle assembly and to the casing wall 42 above the contact area of the oil vapour jet 32, the oleophobic material preventing backstreaming by preventing oil from weeping over the coated surfaces. Alternatively, a baffle cap 56, Fig. 5, coated with or made of oleophobic material, may be mounted on top of cowl 34. The coating may extend over the exterior of the baffle cap or the cowl, and also partly over the interior, as shown, or may extend only along the edge of the skirt. The baffle cap may be formed with a thickened lower edge and a lip, Figs. 6 and 7 (not shown) to prevent oil drops from being optically exposed to the pump inlet 18. |
