Precautions for installing check valves

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A check valve, also known as a one-way valve or non-return valve, serves to prevent the medium in the pipeline from flowing in reverse. The bottom valve at the water pump’s suction side also belongs to the category of check valves. A valve in which the closing element opens or closes on its own due to the flow of the medium and external force, in order to prevent backflow of the medium, is called a check valve. Check valves belong to the category of automatic valves; they are primarily used in pipelines where fluid flows in one direction only, allowing the fluid to move in that direction alone in order to prevent accidents. Classified by structure, check valves can be divided into lift-type check valves, swing-type check valves, and butterfly check valves. Lift-type check valves can be divided into vertical check valves and horizontal check valves. Swing check valves are divided into three types: single-disc check valves, double-disc check valves, and multi-disc check valves. Butterfly check valves are straight-through check valves. The aforementioned types of check valves can be classified, in terms of connection method, into threaded check valves, flanged check valves, and welded check valves. The following points should be considered when installing check valves: 1. Do not allow the check valve to bear any weight within the pipeline; large check valves should be supported independently so as to remain unaffected by the pressures generated by the piping system. 2. During installation, ensure that the direction of medium flow is consistent with the arrow indicated on the valve body. 3. Lift-type vertical flap check valves should be installed on vertical pipes. 4. Lift-type horizontal disc check valves should be installed on horizontal pipes. What is a vertical check valve? Vertical check valves are widely used in systems where it is necessary to prevent the backflow of fluid, such as at the outlet of water pumps, at the hot water supply side, and at the suction side of centrifugal water pumps. Their purpose is to prevent the various consequences that can arise from backflow of the medium. For example, if a vertical check valve is not installed at the outlet of a water pump, the high-speed backflow of water when the pump stops suddenly can cause severe damage to the pump’s impeller. If a vertical check valve (foot valve) is not installed at the suction end of a centrifugal pump, it is necessary to fill the pump each time it is started up.