Abstract: Disclosed herein is an automatic shut off valve for a sprinkler system which closes the water flow path whenever a sprinkler head becomes dislodged from a riser pipe. The shut off valve includes a valve seat and a valve element. The valve element is attached to the stem of a valve assembly, which further includes a flange positioned in the water flow path. The valve element assembly is held away from the valve seat by a coil spring into which the stem of the valve assembly extends. The stem further includes a plurality of openings to allow water flow into the center of the flange and out through openings in the stem and thereafter through the center of the valve seat. The spring is calibrated in length and compression such that, during normal water flow with a head attached, the spring is not sufficiently compressed to allow the valve element to contact the valve seat.