Where should the check valve be installed? Did you install it right?
Today, we will discuss the installation position of
check valve. How to determine the installation position of the
check valve? What is the difference between the
check valve installed before the pump and after the pump? Where is the installation before the pump applicable?
Check valves are usually used with other valves. Where should
check valves be installed when it is used with other valves? Let's talk about it.
Check valve, also known as cut-off valve, is an automatic valve. It 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 and the check valve disc is closed, it can effectively prevent the backflow of the medium in the pipeline, which plays a great role in ensuring the safety of the pipeline.
According to the structure, check valve can be divided into lift check valve, swing check valve and butterfly check valve. Lifting check valve can be divided into vertical and straight type. Swing check valve is divided into single valve type, double valve type and multi-valve type. Butterfly check valve is divided into butterfly double disc and butterfly single disc. The above-mentioned check valves can be divided into screw connection, flange connection, welding and clamp connection.
The installation of check valve is to ensure the flow direction of the internal water pump, so as to ensure the normal operation of the pump. Therefore, the installation position of the check valve，before or after the water pump，can be divided into two situations:
1. The check valve is installed in front of the pump vertical suction pipe end, also known as the bottom valve. The purpose is to fill the pump with water without pumping primary water, because when there is no water in the pump and in the suction pipe before the pump, the pump can only run without water. Then, the pump must be filled with water before pumping water. The installation of the pump is higher than the liquid level of a method, also known as negative pressure method.
2. The other is that the check valve is installed in the rear of the pump. This installation method is that 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, which can prevent backflow.
The check valve must be installed at the outlet of the pump and in front of the outlet control valve to facilitate the maintenance of the check valve. Generally, the first outlet of the pump is a soft connection (shock absorber), then a check valve, and then a block valve (such as butterfly valve, gate valve, globe valve, etc.)
1. First install check valve and then install gate valve or butterfly valve.
Advantages: it can protect the check valve, especially in parallel pump. When one pump does not start and its outlet valve is closed, and the other pump starts, the impact force is borne by gate valve or butterfly valve. After the check valve fails, the inlet and outlet valve isolation system can be closed for repair.
Disadvantages: who will protect the gate valve or butterfly valve? There was a case where the valve plate of butterfly valve was broken.
2. Install gate valve or butterfly valve first and then install check valve.
Advantages: it can protect butterfly valve or gate valve, and the impact force is borne by check valve.
Disadvantages: who will protect the check valve? The check valve is opened and closed by the pressure difference. If the main pipe pressure is high, the pump pressure is high. If the flow rate used is unstable, the check valve will be opened and closed repeatedly, which will affect the service life of the check valve. Moreover, the check valve is broken, especially the main control system, which needs to be stopped before repair.
Generally speaking, due to the frequent opening and closing of check valves, the internal connecting parts and sealing parts are easy to be damaged, the check valve will be installed in front of the outlet gate valve or butterfly valve in order to facilitate repair and prevent the shutdown of the whole system due to check valve failure. Is this what you see basically?
