Check valve, also known as check valve, is an automatic valve, it depends on the pressure of the flow medium in the pipeline to promote the valve disc, to achieve the valve closed and open, when the medium stops flowing, check valve disc 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.
Check valve according to the structure of the division, can be divided into lifting check valve, swing type check valve and butterfly check valve three. Lifting check valves can be divided into vertical and straight-through type two. Swing check valve is divided into single - valve, double - valve and multi - valve type three. Butterfly check valve is divided into butterfly double flap, butterfly single flap, the above several kinds of check valve in the connection form can be divided into thread connection, flange connection, welding and clamp connection four kinds.
The installation of check valve is to ensure the flow of 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 the pump or after the pump, can be divided into two situations:
One is installed in front of the pump vertical suction pipe end, also known as the bottom valve. The purpose is not to pump a water pump to fill a water pump, because the pump and the suction pipe before the pump without water when the pump can only idling pumping water, so the pump must be filled with water to pump water. The installation of this pump is a method of higher than the liquid level, also known as the negative pressure method.
The other is installed behind the pump. This installation method is higher than the water pump, convenient to start and stop the water pump without closing the water pump outlet valve, especially for the mother control water pump system, to prevent the occurrence of backflow.
The check valve must be installed at the outlet of the pump, prior to the outlet control valve, in order to service the check valve. The first outlet of the general pump is the soft connection (shock absorber), followed by the check valve, followed by the partition valve (such as butterfly valve, gate valve, globe valve, etc.)
1. Install check valve first and then install gate valve or butterfly valve
Advantages: protects check valves, especially in parallel pumps, where when one pump is not started and its outlet door is closed, the impact is borne by gate or butterfly valves when the other pump is started. When the check valve fails, the inlet and outlet valve isolation system can be closed for repair.
Disadvantages: gate valve or butterfly valve who will protect? Once there was a case, the butterfly valve disc was broken.
2. Install gate valve or butterfly valve first and then install check valve
Advantages: can protect butterfly or gate valves, impact borne by check valves.
Disadvantages: check valve who to protect, check valve is on the pressure difference to switch, if the main pipe pressure is high, the pressure of the pump is high on the open, if the use of unstable flow, then check valve will repeatedly switch, will affect the life of the check valve. And the check valve is broken, especially the mother control system, which needs to be shut down before it can be repaired.
In general, as a result of the check valve opening and closing action is more frequently, internal connection parts and sealed parts are prone to damage, for ease of repair, prevent due to check the situation of the fault and shut down the whole system, from this point of view, the check valve will be packed in export before the gate valve or butterfly valve, is basically all you see is this?
