A fire protection sprinkler head of the automatic type including a latch for retaining a valve closure in standby position until a thermally responsive element releases the latch at a preset temperature to thereby release the closure to allow flow of fire-retarding fluid, the latch including a catch,...http://www.google.com.au/patents/US4618002?utm_source=gb-gplus-sharePatent US4618002 - Fire protection sprinkler head
