Abstract: A pressure stabilizer for use in hydrocarbon storage facilities which acts as an orifice and also permits the pressure in the system to be stabilized when it reaches a given amount. The stabilizer has a casing with a valve seat and a heavy ball located above the valve seat so that the ball is forcibly displaced upwards when the pressure in the hydrocarbon storage facility reaches an amount sufficient to lift the weight of the ball. Support members extending from the side of the valve seat suspend the ball away from the valve seat a sufficient distance to form the appropriate sized orifice and to minimize contact of the ball to the casing so that the possibility of the stabilizer being frozen closed is minimized.