How to determine the installation position of the check valve? What is the difference between the installation of the check valve before the pump and the installation of the check valve after the pump, and where does the installation before the pump apply? Check valves are usually used in conjunction with other valves. When used in conjunction with other valves, where should the check valves be installed?
Check valve, also called check valve, is an automatic valve. It relies on the pressure of the flowing medium in the pipeline to push the valve flap to close and open the valve. When the medium stops flowing, the check valve flap closes and prevents The medium in the pipeline flows back, which plays a great role in ensuring the safety of the pipeline.
The check valve is installed to ensure the flow direction of the water inside the pump, so as to ensure the normal operation of the pump, so the installation position of the check valve, whether it is installed before or after the pump, can be divided into two situations:
One is to install at the end of the vertical suction pipe in front of the water pump. 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 run idling and cannot pump water, so the water pump must The water can only be pumped out when it is full of water. The installation of this pump is a method when it is above the liquid level. It is also called a negative pressure method, such as pumping water up from a well.
Another way to install the pump is that the liquid level is higher than the pump. This method is generally used for secondary water supply. Because the liquid level is higher than the pump, it is not necessary to close the pump outlet valve when starting and stopping the pump, so the check valve should be installed in The rear of the water pump.
The check valve must be installed at the outlet of the pump and before the outlet control valve in order to check the check valve. Generally, the first outlet of the pump is the soft connection (shock absorber), the next is the check valve, and then the isolation valve (such as butterfly valve, gate valve, stop 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 and the other pump starts, the impact force is borne by the gate valve or butterfly valve
Disadvantages: Who will protect the gate valve or the check valve? There was a case where the valve plate of a butterfly valve was broken.
2. Install gate valve or butterfly valve first and then check valve
Advantages: It can protect the butterfly valve or gate valve, and the impact force is borne by the check valve
Disadvantages: Who will protect the check valve? The check valve is switched on and off by the pressure difference. If the pressure of the main pipe is high, it will be closed, and the pressure of the pump will be opened. If the flow rate used is unstable, the check valve will switch repeatedly. Affect the life of the check valve