| 摘要 |
<p>1,059,273. Valves. ALLEGHENY PLASTICS Inc. April 16, 1964 [April 30, 1963], No. 15762/64. Heading F2V. A two-part rotary spherical ball valve housing (9, 10) (Fig. 3, not shown) is bolted together about a single continuous sleeve (29) of corrosion resistant material, e.g. polytetrafluoroethylene or copolymers thereof with ethylene and chlorotrifluoroethylene, polychlorotrifluoroethylene and copolymers thereof, polyethylene, polypropylene or polyvinyl chloride, which is resiliently pressed into contact with a corrosionresistant spherical closure (16) by rings (30) of resilient material, e.g. silicone rubber. With polytetrafluoroethylene employed as a corrosion and high temperature resistant material, the sleeve (29) is a close fit around the polytetrafluoroethylene coated metal closure (16) and a clearance of 0À010 to 0À030 inch is provided between the sleeve (29) and valve closure chamber (15) to allow for the higher thermal expansion of the P.T.F.E. The sleeve (29) is formed from a machined blank (32) which is stretched by semi-cylindrical bars (33a and 33b) (Figs. 4, 5 and 8, not shown), at 430‹ to 470‹ F., then cooled and, after insertion of the closure (16), is shrunk thereupon utilizing the " plastic memory " of P.T.F.E. by heating to 700‹ to 730‹ F. The valve stem (21) is sealed by packing comprising a P.T.F.E. ring (27a) backed by a silicone rubber ring (27b) resiliently pressing the ring (27a) against the sleeve (29).</p> |
