Check Valve Function and Structure
A check valve is a device designed to prevent a liquid or gas from flowing backward in a system. It is a one-way valve, that is, it allows the medium to flow in one direction only. The function of a check valve is important in protecting the integrity and safety of any piping system.
Structurally, a check valve consists of an inlet and an outlet, one or two discs and a frame. The disc(s) is sealed against the frame of the valve with a gasket or other sealing material. The inlet and outlet directions of the valve are clearly marked on the external surface.
Check valves are designed to guard against reverse flow of fluids, gases and vapors. In the full closed position, the disc seals against the body of the valve, preventing backflow in the system. When the pressure or flow of the medium in the system rises above a predetermined level, the disc lifts slightly, then pivots to allow the medium to pass in the required direction. The movement of the disc is usually caused by a higher pressure differential between the inlet and outlet, or by a spring inside the valve which is designed to open the valve even with a small differential.
Check valves are typically classified according to the action of the disc. Discs can swing, pivot, lift and slide. The swing check valve is the most common type found in industrial systems. It consists of a disc that swings on a hinge when opened, and is held in place by a spring. Pivoting disc check valves pivot on an axle when the flow of the medium forces the disc open. In lift check valves, the disc slides along a vertical plane and is held in the closed position by a spring. Sliding disc check valves use a cylinder inside the body of the valve that seals and opens the valve when the force of the medium exceeds the spring force.
Check valves are also classified according to their material. There are valves made of stainless steel, plastic, brass and other materials. The valve material should be carefully chosen to match the requirements of the system, in terms of pressure and temperature, flow rate and other factors.
Check valves are used in a variety of applications, including in power generation, production equipment and marine systems. They are also used in water, chemical and oil pipelines.
In addition to being useful, check valves also save money. When correctly specified and installed, valves can improve system performance, reduce maintenance requirements and increase safety. Properly sizing and installing valves is key to their success.
In conclusion, check valves are important components of any piping system. They ensure the integrity and safety of the system, and ensure the efficient and reliable delivery of a fluid or gas. Additionally, check valves provide a cost savings, as a well-designed and properly installed valve will reduce maintenance requirements and increase safety.
