Where is the check valve installed?

Where is the check valve installed? What is the difference between installation before the pump and installation after the pump?

How to determine the installation position of check valve? What is the difference between a check valve installed before the pump and a check valve installed after the pump? Where is it suitable for installation before the pump? Check valves are usually used in conjunction with other valves. So when used in conjunction with other valves, where should the check valve be installed?

Proper check valve installation position is very important for the proper operation of the piping system. Check valves should be installed at the beginning of pipelines, at the outlet of pumps or pressure sources, and at high and low points in elevated and horizontal pipelines. Installing a check valve can prevent backflow of media, protect the pump or pressure source, improve the efficiency of the system, and reduce maintenance costs. Therefore, when designing and installing piping systems, it is important to pay attention to selecting the appropriate location to install the check valve.

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 Preventing the backflow of media in the pipeline 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.

Check valve installation location 

1. The starting point of the pipeline

Check valves are usually installed at the beginning of the pipeline to effectively prevent backflow of the medium. In a pipeline system, the medium usually flows from the starting point of the pipeline to the end point. Without a proper check valve installed at the starting point, media may backflow, causing process failure or damage to other equipment.

2. Outlet of pump or pressure source 

Another common location for check valve installation is at the outlet of a pump or pressure source. A pump or pressure source often generates high pressure, which can cause damage to the pump or pressure source without a check valve to prevent backflow. Therefore, it is necessary to install a check valve at the outlet of the pump or pressure source. 

3. Installation at high places

In piping systems, it is sometimes necessary to install check valves at high locations. This usually occurs in vertical pipes or in high sections of pipes. In this case, the function of the check valve is to prevent the medium from flowing back due to gravity.

4. High and low points of horizontal pipes

It is also necessary to install check valves at high and low points in horizontal pipelines. When there are high and low points in the pipeline, liquid backflow may occur due to the characteristics of the liquid. Installing check valves at high and low points in the pipeline can effectively prevent liquid backflow.

5. Branch pipes 

It is also important to install check valves at branch pipes. When the medium flow rate of the branch pipe is small or the pressure of the medium is low, the risk of reverse flow is higher. Installing check valves can ensure that the flow direction of media in the pipeline system is correct.

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 butterfly valve, gate valve, globe valve, etc.)

1. Install the check valve first and then the gate valve or butterfly valve.

Advantages: 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. 

Disadvantages: Who will protect the gate valve or butterfly valve? There was a case where the valve plate of the butterfly valve was broken.

2. Install the gate valve or butterfly valve first and then the check valve.

Advantages: It can protect butterfly valves or gate valves, and the impact force is borne by the check valve.

Disadvantages: 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 The valve will be installed before the outlet gate valve or butterfly valve. 

The importance of check valves

1. Prevent medium backflow 

The main function of the check valve is to prevent the backflow of media in the pipeline system. Backflow may cause process failures, affect the normal operation of the system, and even damage other equipment.

2. Protect pump or pressure source 

Backflow may cause damage to the pump or pressure source. Installing a check valve prevents backflow and protects the proper operation of the pump or pressure source.

3. Improve system efficiency

By properly installing check valves, you can increase the efficiency of your system. Check valves can ensure the correct flow direction of media in the pipeline system and avoid waste of media and energy consumption.

4. Reduce maintenance costs

Properly installed check valves can reduce system maintenance costs. Backflow may cause damage to other equipment, requiring repair or replacement. Installing a check valve can effectively reduce this risk and reduce maintenance costs.