Patent ID: 7143775

Claim:
In a valve element ( 3 , 6 , 10 ) having a frame, at least one inlet and at least one outlet, a passage connecting the inlet and outlet, at least one burst or rupture disk ( 13 , 35 , 63 ) which, when unbroken, closes the first passage connecting the inlet and outlet, and a piston element ( 15 , 36 , 65 ) provided with a piercing element for piercing the burst or rupture disk, the improvements in that: a piston rod ( 16 , 38 , 66 ) of the piston element is sealedly fitted to a wall of a cylinder space for the piston element; the piston element ( 15 , 36 , 65 ) is provided with a passage portion ( 17 , 39 , 67 ) the passage portion extending axially through the piston element and forming a part of the passage only after the burst or rupture disk ( 13 , 35 , 63 ) has been pierced; and a cross section of the piston rod is smaller than a piston surface of the piston element.