The swing check valve is a check valve with a valve disc that rotates around the rocker axis within the body cavity. The opening and closing principle of the swing check valve is the same as that of a lift check valve, which relies on fluid pressure and the valve disc's own weight to act. However, the method of opening and closing the valve disc is by rotational movement instead of vertical movement, and the inlet direction of the fluid should be on the side where the valve disc can be impacted and rotated.
The closing component of the swing check valve is a valve disc or circular plate that is suspended within the valve chamber and is equivalent to the pipe diameter. When fluid flows in a forward direction, the valve disc opens due to the pressure of the fluid, and when the pressure decreases, the valve disc closes due to its own weight and the pressure of the backflowing fluid.
The swing check valve is made up of a valve body, a valve cover, a valve disc, and a rocker. The valve disc has a disc-like shape and rotates around a pivot pin outside of the seat channel. The internal channel of the valve is streamlined, and its flow resistance is lower than that of a lift check valve with a straight-through channel. Therefore, it is suitable for large-diameter pipelines. However, its sealing performance is inferior to that of a lift check valve under low pressure. To improve the sealing performance, an auxiliary spring or a heavy hammer structure can be used to assist in sealing.
Because of the weight of the valve disc, the resistance of the fluid is relatively large when the swing check valve is open. Additionally, since the valve disc is suspended in the fluid, it can cause turbulence in the flow. This also means that the pressure drop through the swing check valve is higher than that of other types of check valves. When the direction of flow suddenly changes, the valve disc will close violently against the seat, causing significant wear to the seat and generating water hammer along the pipeline. To overcome this problem, damping devices can be installed on the valve disc, and metal valve seats can be used to reduce seat wear.
The swing check valve is generally horizontally installed, so the fluid passage is mainly straight during the opening process, and the fluid resistance is lower than that of a lift check valve. Due to its structural characteristics, the swing check valve is suitable for larger diameter applications. In Utmost check valve factory, The swing check valve can be classified into three types according to the number of valve discs: single-disc swing check valve, double-disc swing check valve, and multi-disc swing check valve. The single-disc swing check valve is generally suitable for medium-diameter applications. When a single-disc swing check valve is used in large-diameter pipelines, to reduce water hammer pressure, it is best to use a slow-closing check valve that can reduce water hammer pressure. The double-disc swing check valve is suitable for larger and medium-diameter pipes. The clamp double-disc swing check valve has a small structure and a light weight, making it a promising product. The multi-disc swing check valve is only suitable for low-pressure and large-diameter pipelines.
The swing check valve can also be installed vertically, but it is important to avoid the valve disc reaching its dead point. In the case of vertical installation, the closing torque of the valve disc is produced by its weight, so the valve will close slowly when it is fully opened. To overcome the drawback of the valve lag in response to stagnant media, a lever-weight mechanism or spring can be used to assist in loading the valve disc.