Abstract: A combination high pressure and vacuum relief valve to relieve excess pressure buildups and overload surges in gas and fluid flow lines, to release and break up any vacuum conditions which might develop in the opening and closing of flow in such lines, to serve as an air bleeder device to exhaust trapped air when the flow system is started up and to provide an air cushion against any slam or hammer action in the operation of the valve. A gravity operated vacuum breaker buoyant closure means is used with a pressure relief vented valve means operably connected to an air cylinder.