Piston-type thermally activated relief device

In combination, a pressurized vessel having an opening therein and a thermally activated relief device mounted in said opening for releasing gas from said pressurized vessel when the temperature adjacent said vessel exceeds a predetermined threshold, said thermally activated relief device comprising:

• a body having an inlet, an outlet, and a fluid flow passage communicating with said inlet and outlet;
• said body further including a fluid escape passage having a member therein comprised of a sintered metal which is porous to gases and liquids but not to solids;
• a plug of a fusible material which melts at a predetermined temperature adjacent to said member;
• and
• a piston positioned in said fluid flow passage having first and second ends, said first end of said piston being normally biased into a sealing relationship with said inlet and said second end abutting and applying a compressive force on said plug.

A thermally activated relief device comprising:

• a body having an inlet, an outlet, and a fluid flow passage communicating with said inlet and outlet;
• said body further including a fluid escape passage having a member therein which is porous to gases and liquids but not to solids and includes numerous small flow passages providing tortuous flow paths for a fluid;
• a plug of a fusible material which melts at a predetermined temperature adjacent to said member;
• and
• a piston positioned in said fluid flow passage having first and second ends, said first end of said piston being normally biased into a sealing relationship with said inlet and said second end abutting and applying a compressive force on said plug.