Miller Center Guided Valves afford the very minimum in pressure loss due to the specially designed disc and VENTURI design at outlet. Unlike most check valves having a concave or even flat surface disc, which not only creates greater pressure drop, but actually encourages corrosion, and the deposit of dirt and other foreign matter . . resulting, in many cases, in the valve sticking, Miller's disc is CONVEX in design allowing the fluid or gass COMPLETE STREAM FLOW past the disc and through the valve. The very fact that the disc is so designed for the streamline flow offers the great advantage of washing dirt and other foreign metter from the seat while the valve is in operation. Result . . . Low Pressure Loss . . . NO STICKING . . . Hence, Greater Efficiency and Low Maintenance.