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Description About Check Valve
Check valves, also known as non return, are designed to prevent backflow of media in the line. The valve of the opening and closing member is opened or closed by the flow of the medium and the force to prevent the back flow of the medium from being called a Check Valve. Check valves are automatic valves, mainly used on pipes with one-way flow of media, allowing only the media to flow in one direction to prevent accidents.
The check valve is divided into structures according to the structure, and can be divided into three types: Lift Check Valve, Swing Check Valve and butterfly check valve. Lift check valves are available in both vertical and horizontal versions. The swing check valve is divided into three types: single-lobed, double-lobed, and multi-lobed. The butterfly check valve is straight-through. The above several check valves can be divided into three types: thread connection, flange connection and welding. The structure of the lift check valve is generally similar to that of the shut-off valve. The valve flap moves up and down along the center line of the passage, and the action is reliable, but the fluid resistance is large, which is suitable for small-caliber occasions. Lifting check valves are available in both straight and vertical versions. Straight-flow lift check valves are generally only installed in horizontal lines, while vertical lift check valves are generally installed in vertical lines. The valve flap of the swing check valve rotates around the rotating shaft. Its fluid resistance is generally smaller than that of the lift check valve, which is suitable for larger diameter applications. According to the number of flaps, the swing check valves can be divided into three types: single flap swing type, double flap swing type and multi-lobed swing type. Single-lobed swing check valves are generally suitable for medium caliber applications. When the single-valve rotary check valve is used for the large-diameter pipeline, in order to reduce the water hammer pressure, the slow-closing check valve that can reduce the water hammer pressure is used. The double-valve swing check valve is suitable for large and medium diameter pipes. The double-valve swing check valve has a small structure and light weight, and is a fast-developing check valve; the multi-lobed swing check valve is suitable for large-diameter pipes. The butterfly check valve has a structure similar to a Butterfly Valve. The structure is simple, the flow resistance is small, and the water hammer pressure is also small.
The installation of the check valve should pay attention to the following: 1. Do not bear the weight of the check valve in the pipeline. The large check valve should be independently supported so as not to be affected by the pressure generated by the pipe system. 2 , the installation should pay attention to the direction of the medium flow should be consistent with the direction of the arrow in the valve body. 3. The lift vertical flap check valve should be installed on the vertical pipe. 4. The lift horizontal flap check valve should be installed on the horizontal pipe.