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Advantages of check valve

1. High reliability: check valve structure is simple, easy to maintain, has good sealing and reliability, not easy to fail.

2. Energy saving: relying on the material itself as the medium pressure difference to achieve opening and closing, do not need additional power equipment, can save energy.

3. High safety: check valve can effectively prevent media backflow and pipeline burst and other accidents, play a role in safeguarding equipment and personal safety.

4. Economical and practical: check valve low cost, simple operation, long service life, widely used in a variety of media flow pipeline system.

Disadvantages of check valve

1. Large resistance: check valves form a relatively closed space at the valve, which will produce a certain resistance in the piping system and increase the energy consumption of the piping system.

2. Pressure loss: In industrial production, the pressure of the piping system varies greatly, which easily leads to excessive pressure loss when the check valve is working, affecting the stability of the piping system.

3. Cleaning is not easy: the internal structure of the check valve is more complex, after a period of time, there will be a certain amount of dirt and sediments inside the valve, cleaning and maintenance is more difficult.

Application Scope of Check Valves

Check valve is suitable for liquid, gas and steam and other media piping system, mainly used in the following areas:

1. water pipelines, to ensure the safety of water quality.

2. heating system, to prevent pump backflow.

3. petroleum, chemical, metallurgy, light industry and other industrial areas of the production process, for pipeline media one-way flow.

4. boiler system of thermal power plant, to ensure one-way flow of water and prevent explosion.

The use of check valves

1. Installation position: check valve in the pipeline system should be used to choose the appropriate location, usually installed at the end of the pipeline or the need to protect the one-way flow of the key position.

2. Installation: check valves should be installed according to the nature of the medium to choose the appropriate material and structure, different types of check valves also have ball valves, butterfly valves, rotary, lifting, rubber core and other different installation methods.

3. Maintenance: In the course of use, regular cleaning and maintenance should be carried out to ensure the normal operation of the check valve.

If you want to learn more, please visit our website Globe Valve.

The development direction of check valve

At present, with the rapid development of the industrial field and the continuous progress of technology, check valves are also constantly innovating. The future development direction mainly includes:

1. Improvement of manufacturing materials: use more advanced manufacturing materials and technology to improve the service life and performance of check valves.

2. Optimisation of structural design: through the improvement of structural design, reduce the resistance and pressure loss of the check valve in the piping system.

3. Intelligent development: combining new technologies such as Internet of Things, cloud computing, etc., to achieve remote monitoring and control of the check valve, and improve the automation of industrial production.

Swing Check Valve - Types and Features

Figure 1: Swing check valve

Swing check valves use a hinged disc that swings open with forward flow and closes against reverse flow, which prevents any backflow. They are essential components in fluid systems that operate with no power and are reliable one-way valves. Swing check valves are cost-effective, are made of a wide range of materials, and have different designs for specific functionality. This article discusses a swing check valve's operation, applications, advantages, and disadvantages.

Table of contents

Swing check valve diagram and operation principle

An inline swing check valve has a disc (Figure 2 labeled B) that can swing on a hinge (Figure 2 labeled A). When closed, the disc rests on the valve seal (Figure 2 labeled C), which is on the inlet side of the valve. When the pressure of the media flowing into the valve is higher than the valve&#;s cracking pressure, the disc raises, the valve opens, and media is allowed to flow through the valve. When the inlet pressure drops, the valve swings shut to block any downstream backflow that may occur. For a comprehensive understanding of check valves, read our guide on check valves.

Figure 2: Swing check valve diagram showing its components: hinge (A), disc (B), and seal (C).

Types of swing check valves

There are several types of swing check valves, each with its own advantages and disadvantages.

Wafer swing check valve

A wafer swing check valve has a very short face-to-face (the distance between the inlet and the outlet). The short face-to-face makes clogging in the valve less likely. Therefore, wafer swing check valves are ideal for small installation spaces and viscous and slurry media.

Figure 3: Wafer swing check valve

Tilting disc swing check valve

Tilting disc swing check valves use a disc that rests in the closed position at an angle rather than vertically. The disc floats in the flowing media. This design has two significant benefits:

• The valve closes faster and reduces the effect of water hammer, which is more prevalent among conventional swing check valves because they slam shut.
• The valve can open at very low flow pressures.

Y swing check valve

Y swing check valves are suitable for applications similar to in-line swing check valves. The added opening makes the Y shape, allowing the user to investigate the inside of the valve without removing it from the system.

Figure 4: Y swing check valve

Materials

Valve body

• Stainless steel: Stainless steel swing check valves are durable and resistant to corrosion and rust, making them suitable for many applications. However, they may not be cost-effective for systems with low pressures or temperatures. While generally resistant to corrosion, not all stainless steel grades are suitable for saltwater applications; for such environments, 316 stainless steel is recommended due to its enhanced resistance to chloride-induced corrosion. These valves typically operate effectively within a temperature range of -20 to 200 &#;C (-4 to 392 &#;F).
• Brass: Brass valves are suitable for high-temperature and high-pressure applications and are more cost-effective than stainless steel valves. They operate effectively within a temperature range of approximately 0 to 90 &#;C (32 to 194 &#;F).

Valve seat

• Teflon (PTFE): Teflon seats have a low coefficient of friction and are chemical resistant. These seats have a working temperature range from -260 &#;C to 260 &#;C (-436 &#;F to 500 &#;F).
• NBR: NBR seats are resistant to oil and have high abrasion resistance. These seals have a working temperature range from -35 &#;C to 120 &#;C (-31 &#;F to 248 &#;F).
• Metal: Metallic seats, while offering high-temperature and pressure resistance, are more prone to leakage compared to rubber seats, and may need corrosion protection in specific environments. The exact temperature range depends on the specific metal used.

Read our chemical resistance guide to learn more about the chemical properties of different materials.

Swing check valve installation

A swing check valve is typically installed horizontally. 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.

The general steps to install a swing check valve are:

1. Ensure that there is no foreign material inside the valve, for example, packing material.
2. Push the disc away from the seat to make sure it functions properly.
3. Align the valve in the correct position by facing the arrow in the flow direction.
4. Install the swing check valve. For threaded end connections, screw the valve ends into the piping. Start by screwing the valve into both ends of the piping until it is hand-tight. Then, use a wrench to further tighten the valve by one half turn. Further tightening can damage the valve. Pay close attention to the threading when starting to screw in the valve. If the valve threading and the pipe threading do not align correctly, cross threading can occur and damage threading.

After installing the valve, run media through it to ensure it flows in the right direction. Also, ensure there is no leaking.

Advantages and disadvantages

Advantages

1. The hinge and disc assembly is shielded from the flow, reducing the chances of viscous or slurry media adhering to it and obstructing the valve's closure.
2. Swing check valves are available in large sizes. Typically, the connection sizes are available from 1/2 to 4 inches (12.7 to 101.6 mm).

Disadvantages

1. Swing check valves are unsuitable for frequent flow reversal and pulsating flow.
2. Swing check valves are generally prone to water hammer issues.
3. Swing check valve closure is typically slower than other check valves (e.g., lift and spring check valves).
4. Less suitable for vertical flow.

Swing check valves applications

• Petroleum and chemical industries: Swing check valves are commonly installed in pipelines for petroleum and chemical processes. They are effective in managing clean process media, ensuring smooth and reliable flow in these critical applications.
• Power plants and refineries: These valves are frequently employed in power plants and refineries to prevent the improper flow of gasses, which could lead to dangerous leaks or fires. Their ability to handle large, predictable flows makes them ideal for these high-stakes environments.
• Gas transmission: In the natural gas industry, swing check valves are used extensively in cleaning, distribution, and compression processes. They help maintain the integrity of gas pipelines by preventing backflow and ensuring safe operation. Learn more in our article about oil and gas check valves.
• Water supply and wastewater treatment: Swing check valves are the most common choice in water supply systems and wastewater pumping. They are effective in preventing backflow and are less prone to clogging, although they may require occasional cleaning if solids build up over time.
• Slurry transport systems: While swing check valves are generally not recommended for media with solid particles or high viscosity, they are still used in slurry transport systems where clogging is less of a concern. Their design allows for easy maintenance and cleaning without removing the valve from the system.
• Low-pressure applications: Conventional swing check valves are not suitable for low-pressure applications, but tilting swing check valves can be used in these scenarios. They offer a solution for low-risk applications where a minimal amount of backflow is acceptable.

Swing check valve symbol

The swing check valve symbol includes a line, arc or semicircle to depict the swinging motion of the valve disc, which allows flow in one direction and prevents backflow. It often features an arrow to indicate the direction of permissible flow.

Figure 5: Swing check valve symbol

Comparison with other check valve types

Ball check valve vs swing check valve

Ball check valves and swing check valves are both cost-effective and commonly used in water and wastewater applications and are both suitable for viscous media. Ball check valves use a spherical ball to block reverse flow and are typically more compact and suitable for low-flow applications. Swing check valves are better suited for higher flow rates and larger pipe sizes. Read our ball check valve article for a thorough comparison between ball and swing check valve types.

Spring check valve vs swing check valve

The spring in a spring check valve is the primary component controlling the valve&#;s cracking pressure and closure. As inlet pressure drops, the spring begins to close the valve until the pressure drops below the valve&#;s cracking pressure, and the valve fully closes. Apart from the construction, the main differences between both valve types are listed below:

• A spring check valve is ideal for reducing loud noises that occur when a swing check valve closes rapidly. Spring check valves are also called &#;silent&#; check valves and they are potentially resistant to water hammer. Swing check valves are prone to water hammer issues.
• As the spring controls closure, a spring check valve can be installed in any orientation (vertical or horizontal) so long as the arrow on the valve body is facing the flow direction. Swing check valves are preferred only in horizontal pipe runs.
• Spring check valves typically cost more than swing check valves.
• Spring check valves have a lower flow capacity than swing check valves.

Learn more in our article Swing check valves vs spring check valves.

FAQs

What is the purpose of a swing check valve?

A swing check valve allows the media to flow in one direction. When the media&#;s pressure drops, the valve closes and prevents backflow.

Is a swing or spring check valve better?

Swing check valves are more cost-effective than spring check valves. However, installation of spring check valves is possible in more orientations.

Where should a swing check valve be installed?

A swing check valve should be installed wherever backflow can contaminate media or damage system parts.