Today we will discuss the installation location of the check valve. How to determine the installation position of check valve? What is the difference between installing check valve before pump and after pump? Where is the installation before pump applicable? Check valves are usually used with other valves. Where should they be installed when they are used with other valves? Now lets discuss it together.
Check valve, also known as check valve, is an automatic valve. It relies on the pressure of the flow medium in the pipeline to push the valve disc to close and open. When the medium stops flowing, the check valve disc closes. It can effectively prevent the medium in the pipeline from backflow, which plays a great role in ensuring the safety of the pipeline.
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Check valves are divided into lifting check valves, swing check valves and butterfly check valves according to their structure. Lifting check valves can be divided into vertical and through type. Swing check valves are divided into three types: single-lobe, double-lobe and multi-lobe. Butterfly check valves are divided into butterfly double-lobe and butterfly single-lobe. The connection forms of these check valves can be divided into threaded connection, flange connection, welding and clamp connection.
Installation of check valve is to ensure the flow direction of water in the pump, thus ensuring the normal operation of the pump. So as to the installation position of check valve, whether it is installed before or after the pump can be divided into two situations:
One is installed at the end of the vertical suction pipe in front of the pump, also known as the bottom valve. The purpose is to fill the pump with water without pumping once, because when there is no water in the pump and the suction pipe in front of the pump, the pump can only idle without pumping, so the pump must be filled with water to pump out water. The installation of this pump is a method higher than the liquid level, also known as negative pressure method.
Check valves must be installed in front of the pump outlet and outlet control valves in order to repair the check valves. The first outlet of a general pump is a soft connection (shock absorber), then a check valve, and then a partition valve (such as butterfly valve, gate valve, globe valve, etc.).
1. Install check valve before gate valve or butterfly valve.
Advantages: Check valves can be protected, especially in parallel pumps. When one pump does not start, its outlet door closes, and the other pump starts, the impact force is borne by gate valve or butterfly valve. After the check valve fails, the isolation system of the inlet and outlet valves can be closed for repair.
Disadvantage: Who protects gate or butterfly valves? In one case, the valve plate of the butterfly valve was broken.
2. Install gate valve or butterfly valve before check valve
Advantages: Butterfly or gate valves can be protected, and the impact is borne by check valves.
Disadvantage: Check valve who to protect, the check valve is to rely on pressure difference to switch, if the main pipe pressure is high, the pump pressure is high, open, if the use of unstable flow, then the check valve will be repeatedly switched on and off, will affect the life of the check valve. And the check valve is broken, especially the master control system, which needs to be shut down before repairing.
Generally speaking, due to the frequent opening and closing action of the check valve, the internal connection and sealing parts are liable to damage. In order to facilitate repair and prevent the whole system from being shut down 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, do you see that basically?