Today we will talk about the check valve installation position. So, how do you figure out where to put the check valve? What is the difference between installing the check valve before and after the pump, and when should the check valve be installed before the pump? Because check valves are frequently used in conjunction with other valves, where should the check valve be installed when used in conjunction with other valves? Let us talk about it.

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The check valve is a self-closing valve. It uses the pressure of the flowing medium in the pipeline to push the flap, allowing the valve to close and open. When the medium stops flowing, the flap of the check valve closes, effectively preventing medium backflow in the pipeline, which plays an important role in ensuring pipeline safety.

The check valve is classified into three types based on its structure: lift check valve, swing check valve, and butterfly check valve. Vertical and straight-through lift check valves are the two types. Swing check valves are classified as single flap, double flap, or multi flap. Butterfly check valves are classified as either double flap or single flap. The above check valves are classified into four connection types: threaded connection, flange connection, welding connection, and wafer connection.

The check valve is installed to ensure the flow direction of the water flow inside the pump, ensuring the pump's normal operation. As a result, the installation position of the check valve, whether it is installed in front of or after the water pump, can be divided into two categories:

A bottom valve is installed at the end of the vertical suction pipe in front of the water pump. The goal is to fill the water pump once without pumping water once, because when there is no water in the water pump or the suction pipe in front of the pump, the water pump can only idle and cannot pump water, so the water pump must be filled with water before it can pump water out. This water pump is installed using a method that is high above the liquid level, also known as the negative pressure method.

The second is located behind the water pump. When the liquid level is higher than the water pump, it is easier to start and stop the water pump without closing the water pump outlet valve, which is especially important for the main pipe water pump system to prevent backflow.

The check valve must be installed before the outlet control valve at the pump's outlet so that it can be repaired. In general, the pump's first outlet is a soft connection (shock absorber), followed by a check valve, and finally a block valve (such as butterfly valve, gate valve, globe valve, etc.)

1. First, install the check valve, followed by the gate valve or butterfly valve.

Advantages: It can protect the check valve, which is especially important in parallel pumps. When one pump is turned off, its outlet door closes, and the impact force is borne by the gate valve or butterfly valve when the other pump is turned on. When a check valve fails, the inlet and outlet valve isolation systems can be closed to allow for repair.

Disadvantages include: who will guard the gate valve or butterfly valve? In one instance, the butterfly valve's valve plate was broken.

2. First, install the gate valve or butterfly valve, followed by the check valve.

Advantages: It can protect the butterfly valve or gate valve, and the check valve absorbs the impact force.

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The disadvantage is that no one will protect the check valve. The check valve is activated and deactivated by pressure difference. If the main pipe pressure is too high, it will be closed, and the pressure of the pump will be opened. If the flow rate is unstable, the check valve will repeatedly open and close. Affect the check valve's lifespan. Furthermore, the check valve is broken, particularly the main control system, which can only be repaired after the system has been turned off.

In general, the internal connection parts and sealing parts of the check valve are prone to damage due to the frequent opening and closing actions of the check valve. From this standpoint, check valves are used to facilitate repairs and prevent the entire system from being shut down due to check valve failure. The valve is installed prior to the outlet gate valve or butterfly valve. Is this what you're seeing?

Check Valve Installation

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.

Table of contents

Check valve purpose

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.

Check valve installation guidelines

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:

• Selection: Choose the check valve according to the pipe&#;s size, media compliance, and flow rate. Choosing the wrong valve can result in premature wear and tear and component failure.
• Positioning: Keep an eye on where the check valve is installed within the piping. Always ensure that the valve is approximately five pipe diameters away from tees, elbows, or other valves that can cause turbulence. As discussed in the next section, all check valves may not function in a vertical piping run.
• Orientation: Note the arrow on the check valve that points towards media flow. The arrow indicates the proper positioning of the check valve relative to the pipe&#;s flow, as seen in Figure 2. The arrow is normally printed on a separate tag or permanently marked on the valve body.
• Pipeline level: Tilting disk and swing check valves have their seating surfaces machined on a 5-degree inclined plane relative to the valve centerline. If the pipeline angle exceeds 5 degrees, the disk may not touch the seat, so the check valve may leak. However, axial flow check valves do not have this problem as they function through an internal spring.

Figure 2: Check valve; The highlighted arrow shows the direction of media flow

Check valve installation in vertical pipe runs

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.

Swing (flapper) check valve installation

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 check valve installation

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.

How to install a check valve

Valve size and type

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.

Check valve and pipe evaluation

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.

Check valve placement

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.

Attaching the check valve

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.

Testing the check valve

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 valve maintenance

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.

1. Clean the check valve thoroughly when it is ready for maintenance; The cleaner, the better.
2. Lubricating the check valve surface and rotating it slightly can keep it working optimally for an extended period.
3. Try to abide by the valve manufacturer&#;s valve maintenance instructions. This is particularly helpful if the manufacturer has special requirements.

How to fix check valves

Check valve leaking

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.

Check valve doesn&#;t open

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.

FAQs

Is it necessary to install a check valve?

Yes, a check valve is necessary to prevent backflow at various locations within a piping system.

How to install a check valve?

A check valve can be either screwed to the pipe or simply secured together using a wrench until the parts are sturdy and secure.

Can a check valve be installed horizontally?

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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