Safety valve

A safety valve comprising

• a valve body having an inner wall defining a chamber;
• an inlet conduit in fluid communication with said chamber;
• an outlet conduit in fluid communication with said chamber and downstream of said inlet conduit;
• a clapper, mounted in said chamber to be movable between a first position, in which said clapper seals against a seat to close said inlet conduit, and a second position, in which said clapper is spaced from said seat, allowing fluid flow from said inlet conduit through said chamber to said outlet conduit;
• a spring, positioned to bias said clapper towards said first position and provide sufficient resistance to maintain said clapper in its first position until a predetermined fluid pressure is exerted on said clapper through said inlet conduit;
• a thrust stop having a first surface against which said spring bears, said thrust stop being mounted to said valve body, interposed between said valve body and said clapper, with a second, inner wall surface disposed in a manner to guide movement of said clapper between its first and second positions;
• an impervious membrane, positioned between said clapper and said seat, an outer edge of said membrane being fixed between a third surface of said thrust stop and a first inner surface of said valve body;
• and
• an operating assembly connected with said clapper, said operating assembly comprising a handling member and a handling rod mounted on said handling member and operatively attached to said clapper, said handling member defining a first camming surface and said thrust stop defining an opposed, second complementary camming surface, relative rotation of said first and second camming surfaces causing axial displacement of said handling rod to move said clapper from said first position to said second position.