Robinet à tournant

971,646. Valves. CONTINENTAL MANUFACTURING CO. June 8, 1961 [April 26, 1961], No. 20702/61. Heading F2V. A plug valve comprises a body B, Fig. 8, with each passage 10, 12 terminating in a lip 36, a valve V, and a seal S including passages through which the lips project. The width of the lip of the inlet passage 10 may be wider by 50% or more than that of the outlet passage 12 to ensure that the valve will always shut off first on the downstream side. The seal S thus remains under compression on the downstream side while its portions adjacent the upstream side are not subjected to a high pressure differential. If the seal is volatilized, the valve V is shifted laterally by fluid pressure on its face R to bring the face J into engagement with the lip of the outlet passage. The sleeve cold flows into relief areas 38 and 40, Fig. 6, in the body B and the valve V is sealed by a resilient disc 63 surrounding the spindle 61 and engaged by a gland nut 77. Fig. 10 shows a modified valve in which a non-circular recess 100 is engaged by stem 112 having resilient seals 142, 144 compressed by a screw 172. A second screw 180 engages a plate 184 for applying an axial force to a metallic diaphragm 186 and a resilient diaphragm 188. If the seals are volatilized, fluid pressure in space X separates the stem and valve axially until faces 140, 134 and the end face of the valve and diaphragm 186 are brought into contact to prevent escape of fluid. A halogenated ethylene, such as P.T.F.E., may be used for all of the seals. The valve may control hydrofluoric acid or rocket fuel.