On/off sprinkler head with temperature responsive exhaust port valve

Claim 1

An on/off sprinkler comprising: a two-part body with one body part defining an L-shaped fire extinguishant inlet passage and an inverted L-shaped fire extinguishant outlet passage, the passages being axially spaced with the outlet opening of the inlet passage and the inlet opening of the outlet passage lying in a common vertical plane, and with the other body part defining with said one body part a communicating chamber between the inlet and outlet passages disposed laterally of said common vertical plane and having upper and lower walls with an exhaust port in the latter; a flexible diaphragm clamped between the two body parts and lying in said common vertical plane normally to isolate the inlet and outlet passages from the chamber save for a leakage path between the inlet passage and the chamber, whereby an extinguishant pressure balance is attained at both sides of the diaphragm and from one another; a wall within the chamber parallel with the flexible diaphragm; a compression spring arranged between the wall and the flexible diaphragm serving to urge the flexible diaphragm into its isolating position; a wax motor mounted externally of the other body part on the upper wall in vertical alignment with the exhaust port; a piston rod extending into the chamber from the wax motor and being operable thereby; a valve member freely mounted on the piston rod and normally serving to close the exhaust port, which valve member is movable by the wax motor and piston rod- (A) away from the exhaust port to open the exhaust port upon attainment of a first predetermined temperature value to cause extinguishant pressure imbalance with consequent movement of the diaphragm to connect the inlet and outlet passages, and (B) back towards the exhaust port to close same upon attainment of a predetermined second temperature value; a flange on the piston rod spaced from the valve member; and a spring surrounding the piston rod and arranged between the flange and the valve member and serving to urge the latter in the direction of the exhaust port.