4INCH SDNR

A screw-down non-return (SDNR) valve is a type of globe valve that combines the functions of a globe valve and a check valve: Globe valve: Can be screwed down to stop flow Check valve: Allows flow in only one direction SDNR valves are used in safety-critical systems, such as ship bilge water systems and boiler feed water systems. They can prevent reverse flow when open, provide a leak-tight shut off, and can be used partially open to regulate flow. SDNR valves have a design where the stem does not connect to the disc.