Abstract: The valve in automatic shutoff valve mechanism is held in a predetermined elevated open position by a magnet spaced above the valve, and the valve can be released for downward movement into shutoff position either by melting of a fusible nut holding a threaded magnet-supporting stem or by the mechanism being vibrated sufficiently severely to shake the valve loose from the attraction of the magnet.

Abstract: A valve movable elevationally in a valve casing between a lower closed position and an elevated open position is or carries a magnetizable component of magnetic means. Upward movement of the valve is limited by engagement with an annular stop flange projecting downward from the upper portion of the casing. A permanent magnet component of the magnetic means is received inwardly of the annular stop flange and is movable upward by cooperating screw threads to separate the magnet component from the armature carried by the valve after the valve has been raised from closed position into engagement with the stop flange by elevational movement of the permanent magnet component relative to the valve casing.