| 摘要 |
<p>A needle valve comprises a valve body including a conduit portion through which a flow passage is formed and a bonnet portion which screws into a cylindrical well formed in one side of the conduit portion to intersect the flow passage and form a valve chamber within the valve body. The bonnet portion is bored through to support a valve stem upon which is mounted a frustoconical member, the valve stem and the bore through the bonnet portion being threaded for movement of the frusto-conical member transversly across the flow passage via turning the valve stem. A tubular liner, formed of a flexible material, extends around the periphery of the valve chamber and is split into two semicylindrical sections which receive the frusto-conical member and are spread thereby against portions of the valve chamber wall pierced by the flow passage as the frusto-conical member is seated in the liner. Tabs are formed on the bottoms of the liner to extend into a slot formed in the bottom of the valve chamber to prevent rotation of the liner without interfering with the spreading of the liner to seal the valve against flow through the flow passage.</p> |
