Abstract: A sprinkler head assembly includes a sprinkler head coupling with an interioraly threaded axial passage, an annular shelf surrounding an end of the passage and a sleeve surrounding the shelf and extending an appreciable distance perpendicular thereto. The assembly also includes a sprinkler head having an externally threaded tubular neck that is threadedly engaged in the coupling passage. The neck has a base which defines a valve seat in which a movable valve member is releasably retained by a heat responsive member. The coupling and neck are designed and dimensioned so that when the neck is threaded into the coupling, a dam is present at the inner edge of the shelf that isolates the shelf from the interior of the neck and the valve member thereby preventing any fire protection cement from reaching the valve member in the coupling.