Air Valves in Piping Systems

Dec. 02, 2024

Air Valves in Piping Systems

Air release valves, which expel trapped air in a pipeline, are familiar to most people, but many other types of air valves are out there that have special functions, unique construction for wastewater and sizes up to NPS 20. Safeguarding piping systems from air-related problems requires knowing how to select and install the right air valves.

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TYPES OF AIR VALVES

Three basic types of air valves are defined in American Water Works Association (AWWA) Standard C512 for use in water and wastewater, including:

Air-Release
Air/Vacuum
Combination

AWWA air valves are constructed of iron or stainless-steel bodies with corrosion-resistant trim for water and wastewater service. An important point here is that these air valves have a different function than pressure and vacuum relief valves, which are installed on the top of gas or steam pressure vessels and liquid storage tanks to provide overpressure protection. Relief valves have set points designed to provide overpressure protection and are beyond the scope of this discussion. The air valves presented in this article automatically control the flow of air or gases in and out of liquid piping systems at all operating conditions.

Air Release Valves

Air/Vacuum Valves

A common application for air/vacuum valves is for the discharge of vertical turbine pumps. This is because after shutdown, the piping between the pump and the check valve fill with air. When the vertical turbine pump is started, it rapidly lifts the column of water, and the trapped air must be expelled before the water opens the check valve. An air/vacuum valve is the right fit for this application because it can rapidly expel large volumes of air and close when fluid fills the air valve.

Another optional device for an air/vacuum valve is a slow-closing device. This device is commonly used for pipeline applications where column separation may occur. One purpose of this device is to close when high exhaust rates might occur. It's also to regulate the exhaust rate of the air valve so that the water column does not slam into the air valve and cause water hammer or damage to the air valve. The slow-closing device can be mounted on the inlet of clean water valves and on the outlet of wastewater air valves when column separation or vacuum conditions might occur.

The third type of air valve is the combination air valve, which contains the functions of both the air/vacuum and air release valves. A combination air valve can be furnished either as a single-body design, where a singlebody contains both air release and air/vacuum components, or as a dual-body design (Figure 6), where an air release valve is piped to the side of an air/vacuum valve. The two configurations perform the same functions. However, the single-body design can be more economical while the dual-body design can provide design flexibility when sizing the orifices.

LOCATIONS ALONG A PIPELINE

Air valves are generally installed on liquid piping systems to exhaust air or gases and admit air to prevent vacuum conditions and air-related surges. The AWWA Air Valve Manual recommends air valves at various locations including high points, long runs, adjacent to mainline valves, downstream of pumps and where there are changes in pipe slope. Valve manufacturers provide online computer software to assist in locating and sizing air valves.

Installation methods for air valves are important to ensure their proper function (AWWA, ). The best results are achieved when the air valve is mounted directly on top of the pipe. Unfortunately, some pipelines are located under roadways, which requires the air valve be mounted in a separate vault. In these cases, it is important that the connecting pipe be sized for the flow conditions and slope upward to the air valve. Furthermore, extended air valve piping can have a multiplying effect on surges, so a transient analysis may be needed to evaluate this piping.

For maintenance purposes, all installations should include a shutoff valve under the air valve. Also, to help in collecting the air that travels along a pipeline, a riser pipe larger than the air valve inlet is recommended (Figure 8). A drain valve can be used to annually check the function of the air valve. If the drain valve expels air, the air release portion of the air valve may require maintenance or repair. Otherwise, the air valve should be observed during a pump operation to verify it is exhausting air and closing without excessive leakage.

Caution is needed when inspecting or performing maintenance on an air valve. This is because when the system is functioning, an air valve can release large quantities of air under pressure or admit large quantities of air under vacuum conditions. Both can cause bodily harm. Any maintenance on an air valve requires closing the shutoff valve under the air valve. But even with the shutoff valve closed, pressurized air can be trapped in the air valve. This is why care is needed when venting the air through a drain valve or pipe plug before removing the air valve cover.

CONCLUSION

When air is allowed to accumulate in pressurized pipelines, efficiency is sacrificed, and serious system damage can occur. By having an understanding of the various types of air valves, system designers can better select and install air valves to protect liquid piping systems.'

JOHN V. BALLUN, P.E. is the president and CEO of Val-Matic Valve & Mfg. Corp. (www.valmatic.com). Ballun has been a contributor to valve standards development work for American Society of Safety Engineers, AWWA, and Manufacturers Standardization Society (MSS) and is a past president of MSS. Reach him at .

References

1. American Water Works Association, VALVE Magazine, 'Why Air Valves are Needed in Water Applications,' Spring, , pp. 32-34

2. American Water Works Association, AWWA C512-, Air Release, Air/Vacuum, and Combination Air Valves for Water and Wastewater Service

3. American Water Works Association, AWWA M51, 2nd ed., Air Valves: Air Release, Air/Vacuum, and Combination,

A Quick and Simple Guide to Air Release Valves

In piping systems, air release valves play a crucial role in removing air and preventing system damage. These valves facilitate the release of air during pipe filling, introduce air during pipe emptying, and release air under pressure to ensure the efficient and safe operation of the system.

This guide will provide an in-depth exploration of air release valves, covering their functions, different types, advantages, and disadvantages. Additionally, it will provide useful tips for proper selection, installation, and maintenance.

Av-Tek's valves are manufactured with high-quality materials that guarantee years of reliable service. We're committed to providing excellent products and services that help you create outstanding solutions for your projects and meet individual needs.

To learn more about our range of top-quality valves, check out our product catalog.

How Air Release Valves Work

Air and gas pockets can accumulate in piping systems for reasons such as the temperature of the fluid, the geometry of the pipes, and the pumping rate. The accumulation of air pockets in pipes can lead to problems like reduced flow rates, water hammer, and even system failure.

Air release valves are designed to prevent such problems by automatically releasing air and gas pockets from the pipeline. When air enters the valve, it rises to the top, and its pressure opens the valve's mechanism, allowing the air to escape. The valve will then close once all the air has been released.

Av-Tek's
Air
Release
Valves

Here's a list of the air release valves that we offer at Av-Tek Valves, including the key features, advantages, and applications of each valve. Whether you're looking for a valve for your water and sewage system, wastewater treatment plant, or any other application, we have the right air release valve for your needs.

For more information, please visit Cast Iron Gate Valves Manufacturers.

Our Poly Air Valves are designed with a polyamide (PA) body that is reinforced with fiberglass and are available in 1 lb and 2 lb options. These fully automatic triple-function valves are compact and efficient, with a float made from polypropylene foam and O-Rings made from NSF 61-certified EPDM rubber. The rolling gasket seal is made from potable water-approved silicone rubber.

Polyamide fiberglass air valves are commonly used in distribution lines, pump stations, high points in the line, and before pressure-reducing valves (PRVs) and flow metering devices.

As with all air release valves, our Ductile Iron Air Valves serve three primary tasks:

exhaust air out of the pipeline when the pipe is filling with water
permit air back into the system when the pipe is draining or being dewatered
let air out when the pipeline is under pressure

Av-Tek's series air valves are designed to keep the air out of the pipeline according to the specific application. Our standard air valves can seal anywhere between 20-30 psi, from when you introduce water into the pipe until you hit that pressure to seal the valve.

What sets this product apart is its innovative design, which includes a draining system to avoid wastewater from entering your system. With a drain port cast into the exhaust vent, you can easily attach a drain line with an isolation valve or check valve.

Our -02 Wastewater Air Valves are specifically designed for use in challenging applications where standard air valves cannot be used due to the risk of clogging and damaging internal components.

These valves are ideal for use in sewage main transmission lines, treatment plants, and irrigation systems that involve solids and debris in suspension. We offer two body options: ductile iron or stainless steel bodies, ensuring the valve can handle a variety of harsh environments.

Wastewater air valves play a critical role in ensuring the proper operation of sewage lines, allowing the entrance of a large volume of air in case of a pipe burst or draining, the release of air pockets during working conditions, and the discharge of air during pipe filling. The valve is made with a stainless steel float that is guided by four ribs, which eliminates many of the failure risks of these valves.

The design of our wastewater air valves features a strongly sloped funnel shape to avoid grease deposits and other materials. Maintenance is easy and can be performed from the top without removing the air valve from the pipe.

Maintenance of Air Release Valves

Proper maintenance not only extends the lifespan of air release valves but also helps to prevent damage to other components in the system. Here are some guidelines for maintaining air release valves:

Regular inspection:
Air
release
valves
should be inspected regularly for any signs of damage or wear and tear. This includes checking the body of the valve for cracks, the float for any signs of deformation, and the sealing components for any damage.
Cleaning:
Dirt and debris can accumulate in the valve, leading to reduced efficiency and performance. Cleaning the valve periodically is essential to prevent this. It is recommended to use a mild detergent and a soft brush to clean the valve.
Lubrication:
Air
release
valves
require lubrication to ensure smooth operation. Lubrication should be done periodically using a lubricant that is compatible with the materials used in the valve.
Repair or replacement:
If a valve is found to be damaged beyond repair or is not functioning correctly, it should be replaced or repaired immediately to prevent damage to the system.
Regular testing:
Air
release
valves
should be tested regularly to ensure they are working correctly. This includes testing the valve's automatic or manual release function, checking the valve's ability to release air under pressure, and checking the valve's ability to seal when the pressure reaches the specified limit.

Av-Tek Valves
: Your Reliable Partner for
Air
Release
Valves

Air release valves play a crucial role in ensuring the efficient operation of piping systems by regulating the flow of air and preventing potential damage. When selecting an air valve, it is essential to consider the specific requirements of the application to ensure optimal performance.

If you need assistance in selecting the right air release valve or need help with installation or maintenance, our team of experts is here to help. Contact us to learn more about our products and services and how we can help you keep your piping system in top working condition.

Air Valves in Piping Systems