Where is the check valve installed
Today, let's discuss the installation position of the check valve. How to determine the installation position of check valve? What is the difference between the check valve installed in front of the pump and the check valve installed behind the pump? Where is the check valve installed in front of the pump applicable? Check valves are usually used together with other valves. Where should check valves be installed when they are used together with other valves?
The check valve, also known as the check 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 closes, 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 valves can be divided into lift check valve, swing check valve and butterfly check valve. Lift check valves can be divided into vertical and straight through. Swing check valves are divided into single valve, double valve and multi valve. Butterfly check valves are divided into butterfly double valve and butterfly single valve. The above check valves can be divided into threaded connection, flange connection, welding and wafer connection.
The check valve is installed to ensure the flow direction of water inside the water pump, so as to ensure the normal operation of the water pump. Therefore, the installation position of the check valve can be divided into two situations: whether it is installed in front of or behind the water pump:
One is installed at the end of the vertical suction pipe in front of the water pump, also known as the bottom valve. The purpose is to fill the water pump with primary water without pumping primary water, 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 can not pump water, so the water pump must be filled with water to pump water. The installation of this water pump is a method above the liquid level, also known as 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. When starting and stopping the water pump, there is no need to close the water outlet valve of the water pump, especially for the main pipe water pump system to prevent backflow.
The check valve must be installed at the outlet of the pump and in front of the outlet control valve for maintenance. Generally, the first outlet of the pump is the soft connection (shock absorber), followed by the check valve, and then the block 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, its outlet valve is closed, and the other pump starts, the impact force is borne by the gate valve or butterfly valve. In case of failure of the check valve, 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 that the valve plate of the butterfly valve was broken.
2. Install gate valve or butterfly valve before check valve
Advantages: it can protect 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 opened and closed by pressure difference. If the header pressure is high, it will be closed and the pump pressure will be opened. If the flow 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 pipe system, which can be repaired only after the system is shut down.
Generally speaking, due to the frequent opening and closing actions of the check valve, the internal connecting parts and sealing parts are easy to be damaged. In order to facilitate repair and prevent the shutdown of the whole system due to the failure of the check valve, from this point of view, the check valve will be installed before the outlet gate valve or butterfly valve. Is this basically what you see?
