Today, let's discuss the installation position of the check valve. How to determine the installation position of the 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? Next, we will introduce the specific methods to you.
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The check valve, also known as the non return 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.
Unlike brass ball valves for water, the 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: before or after 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 pump with primary water without pumping primary water. When there is no water in the pump and the suction pipe in front of the pump, the pump can only idle and can not pump water, so the pump must be filled with water to pump water.
The installation of this non return check valve 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.
Another instruction from the bronze pressure reducing valve manufacturers is that 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), the next is the check valve, and then the block valve.
(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.
(2) Install the gate valve or butterfly valve before the check valve
Advantages: it can protect butterfly valve or gate valve, and the impact force is borne by the check valve.
Generally speaking, due to the frequent opening and closing actions of the non return 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, the check valve will be installed before the outlet gate valve or butterfly valve.
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Figure 1: Check valve
Check valves are installed in critical locations to prevent backflow. They are commonly used in plumbing systems to prevent fluid backflow and to protect sensitive equipment, compressors, pipes, and pumps. However, these check valves cannot function properly if they are installed incorrectly. Installation errors can lead to valve leakage and failure, compromising the integrity of the entire piping system. This article discusses the check valve’s installation position and process in detail.
A check valve lets the media pass through in one direction but prevents its flow in the opposite direction. Installing the right check valve can prevent serious issues like water hammers and safeguard the entire process and equipment installed in piping. One of the most common residential examples of check valve installation is for plumbing. A check valve will allow dirty water or sewage to leave the residence through pipes, but prevent it from coming back up from the main discharge back into the house.
It is critical to employ the best practices for check valve installation to reap the full benefits of the valve. Mistakes during installation can reduce the efficiency of the valve or even cause substantial damage to the equipment. Some key factors to check are:
Figure 2: Check valve; The highlighted arrow shows the direction of media flow
A horizontal pipe is always preferred while installing a check valve as it rules out the effect of gravity. Not all check valve styles are suitable for vertical flow directions. There are several applications within buildings and towers, where several applications like sump pumps and mine dewatering require vertical runs to move the fluid vertically up or down.
If a swing check valve is installed on a vertical pipe where the flow is upwards against gravity, the disk may slam against the seat when the flow stops, potentially leading to water hammer. If the flow is downwards as in the case of boiler supply lines and mining applications with limited spacing, the swing check valve will always be open and hence does not deliver its function. Therefore, swing check valves are not preferred in vertical pipe runs and these valves are installed horizontally in most cases.
Spring-assisted axial-flow silent check valves perform well in vertical piping locations. These valves depend on the spring’s potential energy to close the valve. Therefore, the valve closes independently without waiting for the fluid to force its way back into the piping. The strong spring of an axial flow check valve ensures the valve closes before the reverse flow happens, thereby eliminating the water hammer; hence, axial flow check valves are preferred in vertical pipe runs.
Measure the pipe to which the check valve is to be attached and get a check valve that fits the diameter. Also, select a check valve type according to the application. There are threaded valves, socket valves, and various materials like PVC, brass, and stainless steel used to manufacture the valve.
Look inside the valve and check for foreign particles within the valve as these particles can obstruct the smooth flow of media through the valve. Check uneven edges, scratches, or anything that could prevent the check valve from sealing properly. For example, in the case of swing valves, move the flapper by pushing it away from the seating surface to ensure it moves freely. Also, ensure that the pipes are clean and free of debris before installing the check valve.
An arrow on the valve indicates the flow direction; hence, position the valve accordingly on the pipeline (horizontal or vertical). Ensure that the main water supply is turned off during the check valve installation process.
Attach the check valve to the pipeline. Depending on the check valve type, it can be either screwed to the pipe or simply secured together using a wrench until the parts are sturdy and secure.
Turn on the main water supply and let the fluid pass through the installed check valve to test its functionality. If the water gets blocked during testing, double-check the direction in which the valve is installed. If the check valve leaks or any other issue comes to the surface, the user can troubleshoot using the tips mentioned in the next section.
Check valves do not require much maintenance, but they can be kept working more effectively by checking them consistently for leaks, rust, debris, and optimum flow.
Loose bolts or a damaged gasket can cause a check valve to leak from the surface. Tighten the bolts and check if that solves the problem. If not, replace the gasket on the valve.
If the check valve leaks water in a closed position, it indicates damage inside the valve. In this case, clean the internal parts and check for damage. If there is damage to the flap, spring, or ball (depending on the type of check valve used), try replacing the specific part as needed. If there is damage to the valve body, replace the entire check valve.
If the check valve doesn’t open, it may be due to some kind of obstruction within the valve. In this case, uninstall the valve and disassemble the valve to evaluate it. Cleaning the valve thoroughly should clean the debris and allow the water to pass through.
Yes, a check valve is necessary to prevent backflow at various locations within a piping system.
A check valve can be either screwed to the pipe or simply secured together using a wrench until the parts are sturdy and secure.
Yes, a check valve can be installed in both vertical and horizontal pipe runs. However, swing check valves are preferred only in horizontal pipe runs, whereas spring-assisted check valves can be installed in both pipe configurations.
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