A Check Valve is a type of valve that prevents backflow in a piping system. They differ from gate and globe valves because they do not use handwheels to operate and instead rely on pressure or gravity to control the flow. One of the most common types of Check Valves is the swing valve.
When choosing a check valve, the selection process should start with a thorough analysis of the requirements of the application. There are many factors that must be considered, including the line size, pressure gradient, velocity of the fluid, and pumping mechanism. Considering these factors will help ensure that the valve will operate properly and will not damage the equipment. If a valve is not suitable for the application, the process may fail prematurely, resulting in a catastrophic failure.
Check valves are made of various materials, including iron, plastic, and cast iron. Ductile iron, which contains more than 3% carbon, is tougher and easier to form. Cast iron is also widely used in a variety of applications and can withstand high temperatures. It has excellent corrosion resistance, but can be expensive. Stainless steel is another option, which is highly corrosion resistant and can withstand extreme temperatures.
There are two basic types of Check Valves: spring-assisted and spring-loaded. Spring-assisted check valves rely on the force of the spring to keep the discs against the seat. If upstream pressure is too high, it will crack the Check Valve, and the doors will open. The spring force will return the doors to closed position before the flow reverses.
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