Safety device for combustible gas connections - has combined reverse flow shut off valve and gas metering valve

摘要

The device is for use on gas cutting and welding apparatus, is of compact construction with provision for combined back pressure control and reverse flame prevention. The reverse flow shut off valve fits in the housing between gas inlet and outlet and there is a metering valve as well as flame shut off. The two valves are operated by a pressure ram and reverse flow valve is held in the open position by a spring loaded bolt. The valve seat for the metering valve is held in the open position by a spring loaded bolt. The valve seat for the metering valve is at the other end of the bolt and the valve is controlled by a spring loaded piston. The operating ram for the bolt fits in a guide and holds a compressed spring by means of fusible solder. When this melts the ram acts on the bolt via the metering valve piston closing the reverse flow shut off valve.