Valve sealing device

A valve device comprising:

• (a) a valve body having a fluid flow passage and an annular groove extending around and opening toward said flow passage, said valve body including at least one retainer shoulder in said annular groove;
• (b) a valve pivotally mounted in said valve body for opening and closing said flow passage, and having a peripheral surface;
• (c) an annular seal of synthetic resin disposed loosely in said annular groove and having at least one annular shoulder engageable with said retainer shoulder for the retention of said seal in said groove, said annular seal including an annular portion projecting radially inwardly into said flow passage for engagement with said peripheral surface of the valve upon closing thereof, and an annular peripheral contact surface facing radially outwardly toward a radial boundary surface of said annular groove, said annular seal having a first annular pressure chamber of a substantially V-shaped cross section opening at an axial surface thereof in fluid communication with said flow passage, and a second annular pressure chamber opening radially outwardly adjacent to said annular contact surface in fluid communication with said flow passage;
• and
• (d) a resilient metal stiffener ring of a substantially V-shaped cross section disposed substantially complementarily in said first pressure chamber for reinforcing said annular seal, said stiffener ring including an annular flange interposed between said axial surface of the annular seal and an axial boundary surface of said annular groove, said first and second pressure chambers being selectively pressurizable upon closing of said valve for either radially pressing said contact surface and said annular portion of said seal respectively against said radial boundary surface and said peripheral surface of the valve or axially pressing said flange of the stiffener ring against said axial boundary surface.