The sealing principle of swing check valve

The disc of the swing check valve rotates around the rotating shaft in the valve body. The axis of the rotating shaft must be on the same plane as the sealing surface of the valve body to ensure the sealing when closed. The swing check valve can generally only be installed on the horizontal pipeline. When in use, the valve disc is flushed by the working pressure of the medium. At this time, the check valve is opened and the medium passes through; Due to its own weight, the valve disc rotates around the rotating shaft in the valve body, so that the valve disc and the valve seat are tightly closed to achieve the purpose of closing the check valve.

Once the swing check valve is closed, its sealing force is formed. This sealing force is the force of the reverse medium pressure acting on the valve disc, and the sealing specific pressure is formed, which can also ensure the sealing of the swing check valve. The higher the working pressure of the medium in the pipeline, the greater the seal standing, the greater the sealing specific pressure, and the easier it is to ensure the sealing; on the contrary, the lower the medium pressure in the pipeline, the smaller the sealing force and the lower the sealing specific pressure. It is not easy to ensure the sealing. At this time, in order to ensure the specific pressure of the sealing, the sealing surface can only be designed to be narrower to ensure the sealing. But it should be noted that when the working pressure of the medium is very high, the sealing force must be very large, and the sealing specific pressure is also very high. It is necessary to ensure that the actual sealing specific pressure is greater than the necessary sealing specific pressure, and must be less than the allowable specific pressure allowed by the material. Only in this way, the sealing can be ensured and it is safe and reliable.

The swing check valve is generally installed horizontally, so that during the opening process, the medium flow channel is basically in a straight line, so the fluid resistance is smaller than that of the lift check valve. Due to structural reasons, swing check valves are suitable for larger diameter occasions. According to the number of discs, swing check valve can be divided into three types: single disc swing type, double disc swing type and multi disc swing type. Single disc swing check valve is generally suitable for medium diameter occasions. When using a single disc swing check valve for large-diameter pipelines, in order to reduce the water hammer pressure, it is best to use a slow-closing check valve that can reduce the water hammer pressure. Double disc swing check valve is suitable for large and medium diameter pipelines. The double-disc swing check valve has a small structure and light weight, and is a promising product. Multi-disc swing check valve is only suitable for low pressure, large diameter pipelines.

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