Abstract: Fire extinguishing sprinkler apparatus comprises a frame for connection to a source of fire extinguishing fluid and having a passage through which such fluid may flow along a path. The passage normally is sealed by a closure in contact with the fluid. The closure is maintained in its passage sealing position by a retainer which is held by a collapsible strut in such position as to bear upon the closure. When ambient temperature rises to a predetermined level, the strut collapses enabling automatic expulsion of the closure from the passage and flow of fire extinguishing fluid through the passage. The closure is formed from material of poor thermal conductivity thereby preventing cooling of the collapsible strut by the transfer of heat from the strut through the closure to the fire extinguishing fluid in the passage. In one embodiment no part of the sprinkler frame lies in the path of fluid discharged from the sprinkler.

Abstract: Fire extinguishing sprinkler apparatus comprises a frame for connection to a source of fire extinguishing fluid and having a passage through which such fluid may flow along a path. The passage normally is sealed by a closure in contact with the fluid. The closure is maintained in its passage sealing position by a retainer which is held by a collapsible strut in such position as to bear upon the closure. When ambient temperature rises to a predetermined level, the strut collapses enabling automatic expulsion of the closure from the passage and flow of fire extinguishing fluid through the passage. The closure is formed from material of poor thermal conductivity thereby preventing cooling of the collapsible strut by the transfer of heat from the strut through the closure to the fire extinguishing fluid in the passage. In one embodiment no part of the sprinkler frame lies in the path of fluid discharged from the sprinkler.