Today we are going to discuss where to install the check valve. How to decide the installation position of the check valve? Does a check valve go before or after a pump?
How far should check valve be from sump pump? What kind of other industrial valve should be used with check valve? Where the check valve should be when using with other industrial valves?
What is a check valve?
Check valve, also known as non-return valve, is an automatic valve. It replies on the pressure of the flowing medium in the pipeline to push the valve disc to realize the opening and closing of the check valve. When the medium stops flowing, the valve disc will close, the check can effectively prevent the backflow of the medium in the pipeline, which plays a great role in ensuring the safety of the pipeline.
How many types check valve has?
According to the structure, check valve can be divided into three types: lift check valve, swing check valve and wafer butterfly type check valve. Lift check valve can be divided into two types: vertical lift check valve and straight through lift check valve. Swing check valve can be divided into three types: single disc swing check valve, double disc swing check valve, multi-disc swing check valve. Wafer butterfly type check valve is divided into single door wafer butterfly type check valve and double door wafer butterfly type check valve. According to their connect form, those above check valves can be divided into four types: threaded check valve, flange check valve, welded check valve and wafer type check valve.
Does the check valve install before or after sump pump?
The purpose of installing the check valve is to ensure the flow direction of the water inside the water pump, so as to ensure the normal operation of the water pump. Therefore, regarding to the installation position of the check valve,whether the check valve should be installed before or after the water pump, there are two situations:
There is one kind of check valve,which is installed at the end end head of the vertical suction pipe in front of water pump, it is also called foot valve or bottom valve. The purpose of installing a foot valve is no need to fill water each time pumping the water, because when there is no water in the water pump and suction pipe in front of the pump, the water pump can only be idling and cannot pump water, so the water pump must be filled with water before water can be pumped out. The installation of this kind of water pump is a method when it is higher than the liquid level, also it is called the negative pressure method.
The other method is that the check valve is installed behind the water pump. This installation method is that when the liquid level is higher than the water pump, it is convenient to start and stop the water pump without closing the water outlet valve of the pump, especially for the main control water pump system, to prevent the medium backflow.
The check valve must be installed at the pump outlet, before the outlet control valve, in order to maintain the check valve conveniently. Generally, the first part of the pump outlet is a soft joint(shock absorber), followed by a check valve, and then a isolating valve( such as butterfly valve, gate valve, globe valve,etc).
1. Installing the check valve first, following by the gate valve or butterfly valve:
Advantage: which 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 born by the gate valve or butterfly valve. After the check valve fails, the isolation systems of the inlet and outlet valve can be closed for repair.
Disadvantage: there is no protection for gate valve or butterfly valve.
2. Installing the gate valve and butterfly valve first, then followed by the check valve.
Advantage: Installing the gate valve or butterfly valve first can protect the the gate valve and butterfly valve, the impact force is borne by the check valve.
Disadvantage: who will protect the check valve? The check valve is opened and closed by the pressure difference. If the pressure of the main pipe is high, then close the check valve, when the pressure of the water pump is high, then open the check valve, if the flow rate is unstable, the check valve will be repeatedly opened and closed, which will affect the check valve’s service life. And once the check valve fails, especially in main pipeline system, which requires the main pipe system to be shut down before the check valve can be repaired.
Generally speaking, due to the frequent opening and closing of the check valve, the internal connection parts and sealing parts are easy to be damaged. In order to facilitate repair and prevent the entire system from being shut down due to the failure of the check valve, for this consideration, the check valve will be installed before the gate valve or the butterfly valve in the outlet of the pump.
For more articles about check valves, kindly visit:
- What are the 5 types of check valves?
- How to inspect a check valve?
- What is a lift check valve(lift disc check valve)?
- What is wafer type check valve(also called butterfly type check valve)?
- What is ball type check valve?
- What is the difference between gate valve and check valve?
- How does a check valve work on sump pump?