Rotary plug valve

Claim 1

A rotary plug valve, said valve comprising: A valve housing, said housing having inlet and outlet ports; A frusto-conical chamber, said chamber being formed in said housing; A frusto-conical plug, said plug having a flow passage therethrough, said plug being insertable in said chamber, said plug being rotatable in said chamber from a remote position between valve-open and valve-closed positions, said valve-open position being when said plug flow passage is aligned with said inlet and said outlet ports of said housing, said valve-closed position being when said plug flow passage is rotated 90° from said valve-open position from said remote position such that said flow passage is blocked by said housing; A liner for sealing said plug in said chamber, said liner being located between said chamber and said plug when said plug is inserted into said chamber, said liner having apertures which align with both said inlet and said outlet ports, and said flow passage, said liner further comprising: Two plastic members, said plastic members sealing said plug in said chamber, said members comprising an inner plastic sleeve and an outer plastic sleeve, said sleeves being composed of fluorocarbon material, said inner sleeve and said outer sleeve being bonded together where said sleeve surfaces contact, said inner plastic sleeve having a substantial proportion of the radially inner surface of said sleeve being spaced relative to said plug such that thermal relief areas are provided permitting expansion of said plastic members; A rigid support member, said member being at least partly enclosed by said inner and said outer plastic sleeves such that said inner and outer sleeves are in direct contact with both said plug surface and said chamber surface respectively, said members being located such that said inner and said outer plastic sleeves together with said rigid supporting member form said liner, said supporting member being a metal cage having flange portions defining apertures, said plastic sleeves extending radially inwardly and outwardly beyond said flange portion whereby said chamber surface and said plug surface are contacted solely by said plastic sleeves of said liner; Means for preventing said liner for rotating in said frusto-conical chamber, said means having at least one lug, said lug being receivable in at least one correspondingly scalloped recess proximate the top, wider periphery of said frusto-conical chamber of said valve housing; and Means for attaching said liner to said plug such that said liner and said plug form a unit, said unit being removable from said housing, said liner being separable from said plug after said unit is removed from said housing.