Abstract: A check valve has a body with a seat therein and a valve plug movable toward the seat to closed position and away from the seat to open position. The valve plug has a forward face facing toward the seat and body inlet and a rear face facing away from the seat and toward the body outlet. The plug, at its rear face, has a stem of smaller diameter than the rear face so that an annular area of the rear face of the plug is exposed rearwardly toward the body inlet. The stem has fins thereon of a shape to impede the return flow of fluid relative to the stem in a direction toward the seat and thereby assist in rapid closure of the valve. The rear face of the plug is concave rearwardly and slopes inwardly from its outer periphery toward its axis at a very slight angle to further assist in rapid closure, while reducing outward radial components of flow of return fluid.

Abstract: A safety valve for use in gaseous service at elevated temperatures, including a casing provided with an annular valve seat and a selectively moveable valve member having mounted thereon a plastic annular sealing ring for seating on the valve seat. The plastic annular sealing ring is preferably formed of Teflon P.F.A. fluorocarbon and is shrunk fit onto a projecting shoulder portion of a metal seal retainer detachably mounted on the valve member, and the valve seat includes a projecting ridge formed by intersecting flat surface portions disposed at an obtuse angle to one another, whereby the plastic annular sealing ring will be engaged by the valve seat ridge when the valve member is seated.