Where should the check valve be installed?

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Check valve, also called check valve, is an automatic valve that relies on the pressure of the flowing medium in the pipeline to push the valve disc to close and open the valve. When the medium stops flowing, the check valve disc closes, which can effectively prevent the backflow of the medium in the pipeline, which plays a great role in ensuring the safety of the pipeline. Check valves are divided according to structure and can be divided into three types: lift check valve, swing check valve and butterfly check valve. Lift check valves can be divided into two types: vertical and straight-through. Swing check valves are divided into three types: single-disc type, double-disc type and multi-disc type. Butterfly check valves are divided into butterfly double-disc and butterfly single-disc. The connection forms of the above check valves can be divided into four types: threaded connection, flange connection, welding and wafer connection. The check valve is installed to ensure the flow direction of the water inside the water pump, thereby ensuring the normal operation of the water pump. Therefore, regarding the installation position of the check valve, whether it is installed in front of the water pump or after the water pump, there are two situations.: One is installed at the end of the vertical suction pipe in front of the water pump, also called the bottom valve. The purpose is to fill the water pump without pumping water once. Because when there is no water in the water pump and the suction pipe in front of the pump, the water pump can only idle and cannot pump water, so the water pump must be filled with water before water can be pumped out. This kind of water pump is installed above the liquid level, also called the negative pressure method. The other is installed behind the water pump. This installation method is convenient when the liquid level is higher than the water pump. It is convenient to start and stop the water pump without closing the water pump outlet valve. Especially for the main pipe water pump system, it prevents backflow. The check valve must be installed at the outlet of the pump and before the outlet control valve to facilitate access to the check valve. Generally, the first outlet of the pump is a soft connection (shock absorber), followed by a check valve, and then a isolation valve (such as a butterfly valve, gate valve, globe valve, etc.) 1. Advantages of installing the check valve first and then the gate valve or butterfly valve.: It can protect the check valve, especially in parallel pumps. When one pump does not start, its outlet door is closed, and when the other pump starts, the impact force is borne by the gate valve or butterfly valve. After the check valve fails, the inlet and outlet valve isolation system can be closed for repair. shortcoming: Who will protect the gate valve or butterfly valve? There was a case where the valve plate of the butterfly valve was broken. 2. Advantages of installing the gate valve or butterfly valve first and then the check valve: It can protect butterfly valves or gate valves, and the impact force is borne by the check valve. shortcoming: Who will protect the check valve? The check valve is opened and closed by pressure difference. If the main pipe pressure is high, it will close, and if the pump pressure is high, it will open. If the flow rate used is unstable, the check valve will open and close repeatedly, which will affect the life of the check valve. Moreover, the check valve is broken, especially the main control system, and the system needs to be shut down before repair can be carried out. Generally speaking, because the check valve opens and closes more frequently, the internal connecting parts and sealing parts are prone to damage. In order to facilitate repair and prevent the entire system from shutting down due to check valve failure, from this perspective, the check valve will be installed before the outlet gate valve or butterfly valve. Is this basically what you see?