Check Valves

Check valves allow flow in one direction and close automatically to prevent reverse flow. In water and wastewater networks they protect pumps from reverse rotation after trip, prevent backflow from high-pressure zones into lower-pressure mains, protect meters and control valves from bi-directional flow and maintain prime in suction pipelines. Correct check valve selection is critical: the wrong type in a given application can cause damaging water hammer or fail to close reliably under low differential pressure.

Swing check valves are the most common general-purpose non-return valve for water pipelines. The disc swings on a pivot above the flow centreline and drops closed under gravity and reverse pressure when forward flow ceases. Swing check valves have low head loss in the open position, are simple to maintain and are available across the full size range from DN40 to DN1200. They are suitable for horizontal or vertical upward-flow installation and are manufactured to EN 12334.

Tilting-disc check valves use a disc that pivots about a centreline axis, reducing the closing travel and therefore the closure time compared to a conventional swing check. The reduced slam effect makes tilting-disc valves a better choice for pump station applications where flow deceleration is fast. They are available in both flanged and wafer-pattern bodies and are a practical step up from swing check valves where moderate water hammer risk has been identified.

Axial-flow nozzle check valves are the preferred type for pump station applications where water hammer is a significant concern. The spring-assisted closure and short disc travel mean the valve closes before the flow fully reverses, dramatically reducing or eliminating the pressure spike associated with disc slam. These valves are typically specified by hydraulic engineers in conjunction with a surge analysis for new pump station designs.

Silent check valves, using spring-loaded dual-plate or Y-pattern designs, are used in building services and HVAC applications where noise from slam is unacceptable and where frequent start-stop cycles are anticipated. They are compact, quiet and suitable for both horizontal and vertical installation in commercial and industrial buildings.

When specifying a check valve, the key parameters are flow rate, pipe diameter, operating pressure, installation orientation, closure time requirement and the criticality of the downstream system. AFC Valves Europe supplies check valves in ductile iron, cast iron and stainless steel across all major connection standards. Our technical team can advise on the appropriate type and size for your application.