A BS 5352 Check Valve is a non-return valve that complies with the BS 5352 standard, which specifies the requirements for steel check valves 50 mm and smaller. These valves are designed to allow fluid to flow in one direction while preventing backflow, making them ideal for use in the petroleum, petrochemical, and allied industries. The standard ensures that these valves meet specific design, material, testing, and performance criteria for reliable operation in fluid control systems.