Plug valve

Abstract

A plug valve having a valve body with a cylindrical plug receiving opening extending therethrough having at least one terminal end thereof outwardly chamfered. Fluid inlet and outlet passageways communicate with the receiving opening and are chamfered at the areas of communication therewith. A plug member includes a cylindrical plug portion closely received in the body receiving opening. This plug portion has a transverse fluid flow passage which is selectively rotatable into and out of alignment with the valve body inlet and outlet passageways. Axially spaced apart circumferential sealing members disposed on both sides of the flow passage prevent fluid flow outwardly of the receiving opening. An inlet passageway sealing means disposed in the plug portion side wall intermediate the opposite flow passage ends sealingly surrounds the passageway in the valve closed position. A fluid relief channel communicating between the flow passage and plug portion side wall relieves fluid pressure through the outlet passageway as the valve is moved to the closed position. The plug portion advantageously includes a thin coating of plastic material for enhancing its fluid sealing relationship with the receiving opening and for improving ease of rotation between the valve opened and closed positions. The plug member is axially retained in position in the receiving opening by a snap ring at one end and by a handle at the other end. The handle is rotatable only between positively defined maximum valve opened and closed positions. Spaced apart circumferential grooves included in the plug portion side wall receive the axially spaced apart sealing members and at least the bottom walls of these grooves are also coated with the plastic material.