Pressure actuated unit with high temperature protection

The combination comprising:

• a pressure fitting containing a chamber within which a pressurized fluid is received and having an opening leading from said chamber to the exterior of the fitting;
• a pressure responsive assembly formed at least in part of material susceptible to damage by high temperatures encountered under fire conditions, said assembly including a body structure attached to said fitting about said opening, and a pressure actuated part mounted movably to said body structure and actuable relative thereto in accordance with variations in force exerted by said pressure fluid through said opening;
• a movable seal unit through which the force of the pressure fluid is exerted against said pressure actuated part and acting to prevent leakage of fluid from said fitting;
• said fitting being formed of material capable of withstanding high temperatures which would damage said pressure responsive assembly and destroy the integrity of said seal unit;
• and
• a valve-member which responds to destruction and/or deformation of the integrity of the material making up said part of said pressure responsive assembly due to high temperature, said valve member being capable of withstanding said temperatures high enough to damage said pressure responsive assembly and to destroy the integrity of said seal unit and which is held open by said seal unit, but which automatically responds to an increase in temperature to close the opening against loss of fluid therethrough from said chamber.