Cast Iron Wafer Check Valve

 A cast iron wafer check valve is a type of non-return valve designed to allow fluid to flow in one direction while preventing backflow in piping systems. It is compact, durable, and widely used in water supply, wastewater treatment, HVAC, and industrial applications. The term “wafer” refers to its slim, sandwich-like design, which allows the valve to fit between two pipe flanges, saving space and reducing installation costs. The “cast iron” body provides strength and corrosion resistance, making it ideal for handling water, air, oil, and other non-corrosive fluids.

The basic working principle of a cast iron wafer check valve is straightforward. The valve contains a disc or dual plates that open when the forward flow pressure exceeds the cracking pressure — the minimum pressure required to open the valve. When the flow stops or reverses, gravity and back pressure cause the disc to close, preventing reverse flow. This automatic action helps protect pumps, compressors, and other equipment from damage due to backflow or water hammer.

There are several designs of wafer check valves, including single-disc, dual-plate (or double-door), and spring-loaded types. The dual-plate wafer check valve is the most common, featuring two half-discs mounted on a central hinge pin with a spring mechanism. This design ensures a quick, tight closure, reducing the risk of water hammer and pressure surges. The compact structure and lightweight nature of the wafer design make it easier to install in systems where space is limited.

The cast iron wafer check valve is manufactured using high-grade cast iron for the valve body, which offers excellent durability, machinability, and vibration absorption. The internal components such as the disc, hinge, and spring are often made of stainless steel or other corrosion-resistant materials to enhance performance and longevity. The sealing surfaces may also be lined with EPDM, NBR, or Viton rubber to ensure leak-proof operation and chemical compatibility.

One of the main advantages of a cast iron wafer check valve is its space-saving and cost-effective design. Unlike flanged or lug-type check valves, wafer types require fewer bolts and take up less room, making them ideal for compact installations. They can be easily mounted between standard flanges (such as ANSI, DIN, or JIS standards) using standard gaskets and bolts. Their simple construction also ensures low maintenance and minimal pressure drop during operation.