Ductile Iron Swing Check Valve | ANSI 150 Flanged | Class 150LB

Ductile Iron Swing Check Valve — ANSI 150 Flange, Automatic Shut-Off, Low-Pressure Loss Cematic's ANSI flanged ductile iron swing check valve prevents backflow in industrial piping systems with flanged connections. Its swing mechanism allows fluid to flow in one direction and automatically closes when pressure is reversed. This protects pumps, equipment, and piping without operator intervention. In addition, its ductile iron body offers greater mechanical resistance than conventional gray iron, making it a reliable option for medium and high-demand applications. Its ANSI 150 class flanged connection also facilitates installation and replacement in existing piping systems. Consequently, it is one of the most used solutions in installations where protection against water hammer and backflow is required. Operating Principle — Flanged Swing Check Valve The disc swings on a horizontal axis mounted at the top of the body. When the fluid flows in the correct direction, the pressure pushes the disc upwards, opening the passage. When the flow stops or the pressure is reversed, the disc falls by gravity and automatically closes the valve. In this way, the closure does not require electrical or pneumatic energy — gravity acts as a natural closing force. The swing design also offers low pressure loss during normal operation, as the disc opens completely without obstructing the fluid passage. For this reason, it is the type of check valve with the lowest pressure drop due to its design among models with their own body and flanges. ANSI 150 Flanges vs. Wafer Format — When to Choose Flanges The choice between ANSI flanges and wafer format also depends on the type of installation and the operating requirements of the system. The following describes the cases where the version with ANSI 150 flanges is the correct choice: Permanent Process Installations: The flanged valve has its own integrated flanges, so it is mounted as an independent element in the line. This also makes it easy to remove for maintenance or inspection without affecting the pipe flanges. Systems with Limited Pipe Access: Unlike the wafer format, the flanged check valve is disassembled by screwing only its own flanges. It is not necessary to separate the pipe flanges to remove it. Therefore, it is more practical in spaces where separating the pipe flanges is difficult. Frequent Replacement: In installations where the check valve is periodically checked, the flanged connection also facilitates disassembly. Likewise, it does not require moving pipe sections to remove the valve from the system. Advantages of Ductile Iron over Gray Iron Ductile iron is also the standard material in hydraulic infrastructure valves. It offers specific technical advantages over conventional gray iron. The main advantages of ductile iron are described below: Greater Mechanical Resistance: Ductile iron has greater tensile strength and impact resistance than gray iron, so it better withstands pressure variations, water hammer, and mechanical stresses in the pipeline. Greater Ductility: Unlike gray iron, which is brittle, ductile iron deforms before breaking. This characteristic also reduces the risk of sudden fracture under overpressure or impact conditions. Long Service Life: Ductile iron also has greater durability in continuous service than gray iron. For this reason, it is the standard specification in hydraulic infrastructure projects where the service life of the component is a relevant economic criterion. Technical Specifications Parameter Value Valve Type Swing check Connection ANSI 150 Flanges (Class 150LB) Body Material Ductile Iron Mechanism Swing disc with gravity closure Working Pressure 285 psi @ 38°C Max. Fluid Compatibility This ANSI flanged ductile iron swing check valve is suitable for the most common fluids in water and industrial infrastructure systems. The main groups are described below: Potable water and process water — ductile iron is the standard material in potable water distribution; therefore, it is the usual specification in municipal and industrial hydraulic infrastructure projects Raw water and wastewater — suitable for raw water pumping stations, filtration plants, and wastewater treatment systems; ductile iron also resists mechanical stresses in these applications HVAC fluids — chilled water and return water — compatible with standard HVAC system fluids; for water with aggressive chemical treatments, consult Cematic's technical team Agricultural and industrial irrigation water — in irrigation distribution networks, this valve protects the system from backflow during pump shutdowns; ductile iron also offers adequate durability for irrigation installations with continuous service Applications of the ANSI Flanged Ductile Iron Swing Check Valve Pumping Systems The ANSI flanged ductile iron swing check valve prevents backflow when the pump stops. The swing mechanism also protects the equipment against water hammer and extends the life of the pump and piping. For this reason, it is the standard protection component in centrifugal pump discharge lines in industrial and municipal installations. Water and Wastewater Treatment In potable water and wastewater treatment plants, this valve also controls the flow direction in pumping, filtration, and sedimentation stations. Thanks to its ductile iron body, it operates reliably in continuous working conditions. Likewise, the ANSI 150 flanged connection facilitates valve replacement during preventive maintenance without stopping the entire system. Agricultural and Industrial Irrigation Systems In irrigation distribution networks, this valve prevents water backflow due to pressure variations. It also protects the system from pump shutdowns. For this reason, it protects the integrity of the system and reduces pump wear due to reverse flow. In addition, the ANSI 150 flanged connection ensures greater mechanical integrity in installations where the valve may be exposed to pipe stresses or vibrations. Manufacturing and Process Industry In industrial process lines — cooling, fluid distribution — this valve also protects the lines against reverse flow. Consequently, it reduces the risk of cross-contamination between lines and equipment damage due to reverse pressure. Likewise, ductile iron offers the necessary mechanical resistance for continuous service in industrial process installations. HVAC Systems In hot and cold water circuits in HVAC systems, this valve also maintains the correct flow direction. Its swing design also offers low pressure loss during normal operation, so it does not penalize the energy efficiency of the HVAC system. For this reason, it is the correct option when a check valve with an ANSI flanged connection is required in large-scale HVAC circuits. For the complete range of check valves, see check valves collection → Technical Data Sheet