Why is air vent valve Better?

Estimated reading time: 6 minutes

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Photo by SafeHome Inspections

Let's talk about air admittance valves.

Most residential building drainage systems are vented directly through the building's roof. Here's an example. See the white pipe peeking through the roof. The plastic pipe is 'flashed' or sealed at the roof penetration to prevent rainwater from leaking into the building.

During maintenance, you'll want to be assured the top of the vent is kept open. A blocked vent can be caused by leaves, dead animals, and ice dams (in very cold climates). Another 'not-so-common' way the vent can become clogged is when a horizontal section of the venting system (inside the attic) sloped incorrectly. When that happens, it can fill with rainwater or condensation. Experienced home inspectors should be on the lookout for these conditions.

Air Admittance Valves (AAV)

Found during an 11-month builder warranty inspection.

Sometimes we can't (or don't want to) vent through the roof line. In these rare cases, plumbers use an Air Admittance Valve. 

Air Admittance Valves (aka Studor vents) are built with 'negative-pressure-activated' one-way mechanical valves. Used most commonly at an island sink or vanity, the vents may be used to prevent roof penetrations (as seen above) on the front roof line elevation. Think about it ' when have you seen a plumbing vent on the front roof line of a home as it faces the street?

How It Operates

If we didn't have either venting method, you would have a very noisy sink drain. 

A discharge of wastewater down your sink drain causes a valve on the AAV to open. When it opens, the air can enter the plumbing system allowing the water to pass through the waste pipe.

Think of it as holding a large soda, water, or milk bottle upside down and removing the cap. The liquid will come out but won't come out as freely as it would if you poke a small hole (a vent) on the other end of the bottle. We always want to maintain that open vent design in the plumbing system.

The Pros

An AAV can significantly reduce the number of venting materials needed in a plumbing system. That's money in the pocket of the plumber. They also allow greater flexibility in the layout of plumbing fixtures and reduce long-term roof maintenance. If we don't have a hole in the roof, it's easier to maintain it.

AAVs have been effectively used in Europe for more than two decades. However, there are a few limitations.

The Cons

Some state and local building departments prohibit AAVs. Check with your local AHJ ' Authority Having Jurisdiction for more info.

AAVs are certified to reliably. However, anything mechanical can and will fail. Some manufacturers claim they're suitable for 500,000 uses (approximately 30 years).

US manufacturers offer warranties that range from 1 year to 'lifetime.' You'll want to seek out the warranty info. Most plumbers won't have it.

Note: An AAV should not be tampered with or spray painted. I have had plumbers tell us that sewer flies and bugs have been seen at failed air admittance valves. So if you detect a sewer odor under and around your sink or in the attic, the AAV could have let you down.

Inspecting The Studor AAV

1. STUDOR AAVs must be located at least four (4') inches above the horizontal branch drain or fixture drain being vented.
2. STUDOR AAVs shall be accessible should replacement be required. For in-wall installation, use STUDOR recess box/grill combination.
3. STUDOR AAVs' location must allow for adequate air to enter the valve. An opening shall be provided in a wall or attic space lacking ventilation. Locating the valve in a sink or vanity cabinet is acceptable.
4. STUDOR AAVs must be installed in the vertical, upright position. A maximum deviation (in either direction) of 15 degrees is allowed.
5. The vent shall connect to the drain vertically to maintain an unobstructed opening in the piping to the STUDOR AAVs.
6. A minimum of one vent pipe shall be extended to the open atmosphere for each building drainage system for relief of positive pressure; the size of this vent is not specified because this single vent does not determine the total aggregate cross-sectional area of the vent system. The total amount of the cross-sectional area of vents combined on the system has to equal the aggregate cross-sectional area of the building drain. When properly installed, an air admittance valve in the system is equivalent to an open vent pipe having the same cross-sectional area as any other vent. Such open air vent is recommended, not required, to be located as close as possible to the connection between the building drain and building sewer.
7. The Maxi-Vent® must be installed six (6') inches above the highest flood level rim of the fixtures being vented in stack applications.
8. STUDOR AAVs installed in the attic area must be six (6') inches above the ceiling insulation.
9. The use of Tec-Vent® in return air plenums shall be allowed only in engineered drainage systems designed by design professionals and approved by the local authority.
10. The maximum height of the drainage stack being vented by a MAXI-VENT must not exceed six (6) branch intervals unless used with a stack connected to a P.A.P.A. and AAVs on the branches.
11. A relief vent shall be provided when a horizontal branch connects to a stack more than four (4) branch intervals from the top of the stack. The relief vent must be located between the connection of the branch to the stack and the first fixture connecting to the branch. The relief vent may also serve as a vent for the fixture. The relief vent must connect to the vent stack, stack vent, or extend outdoors to the open air unless used with a stack connected to a P.A.P.A. device and AAVs on the branches.
12. Only Teflon® tape can be used on the valves' threads. Using primer, solvent cement, or pipe dope will void the STUDOR warranty.
13. The Redi-Vent®, Mini-Vent®, Maxi-Vent®, Tec-Vent®, and Chem-Vent® must be installed at the finish after the system rough-in and pressure test.
14. Air Admittance Valves may be used on grease traps if they are not subject to positive pressure.
15. Other Information ' Studor PDF

In many types of fluid control related to the flow of water supply, piping air through the system, and avoiding hot water and air safety problems, it's very important to prevent air in the system. In this situation, only an air vent valve can assist you properly. Today, we will explain the functions, uses, problems and solutions, buying guide, and everything necessary about brass air vent valves. So, stay till the last word.

Detailed Insight:

• The Evolution of Air Vent Valves: Tracing back to its inception, air vent valves have undergone significant modifications to meet modern-day requirements. Early models were primarily manual, necessitating human intervention for functionality. However, with technological advancements, automated models were introduced, boosting efficiency and minimizing human error.
• The Anatomy of an Air Vent Valve: An air vent valve is a precision instrument at its core. It consists of an external casing, a float mechanism, a valve seat, and a discharge orifice. Each component plays a pivotal role in its operation, ensuring that the valve functions optimally.

automatic air vent working specifications and sizes

Problems In Pipelines For Air Existence

Common problems and damages that occur when there's a presence of air in the pipelines:

· Fluctuations in the flow and sometimes blockage up to the stoppage.

· Water hammer problem resulting in damage to the plumbing system and accessories.

· Corrosion, cavitwaters, and noise inside the system.

· Water is splashing in the pipe outlet and faucets.

· Improper water supply due to inaccurate meter readings and increased energy costs.

Hopefully, you now understand how much damage the presence of air can do to your pipelines. So, before these problems start, ensure your system has air vent valves for safety.

Now, let's discuss the brass air vent valves'

What Is An Air Vent Valve?

The Air Vent Valve is a mechanical safety valve. It is used to release or remove the existing air from a water supply pipeline to prevent air problems. This valve is also an automatic air vent, bottle air vent, and Air Release Valve (ARV).

How do air vents work? Caleffi Hydronic Solutions

Air Vent Valve Components

An Air vent valve looks like a bottle from the outside. And like every bottle, it has a plug or cover. This plug covers the inner components and offers easy removal. In addition, right at the top of the cover, there's a tiny cap thing. This cap holds the inner mechanism up. If you remove the cap and dive in, you'll see a spring and the locking system.

After removing the plug, the inner mechanism will also come out with it. The lever mechanism and the float are attached to the plug. The lever mechanism here consists of a pin and sticks to play the role of a level. Moreover, it connects to the locking system from one end and the floating from the other. Lastly, the float is a cylindrical or round-shaped and very light in weight.

Above all, the rest you can see outside of the valve is the valve body. At the bottom of the body, the threaded part works as the inlet. 

3/4 inch air vent valve drawing with spare parts

The Working Principle of Air Vent Valves

At the heart of every air vent valve lies its working mechanism'a balance between physics and engineering.

Detailed Insight:

Additional reading:
How much should a pressure relief valve cost?

If you are looking for more details, kindly visit butterfly valve manufacturer.

• The Role of Buoyancy: The valve's float mechanism operates on the buoyancy principle. As air accumulates, the float's buoyancy decreases, causing it to drop and open the valve. This intrinsic mechanism ensures automatic air release without requiring any external intervention.
• Air Intake Mechanism: Contrary to air release, there are scenarios where the system might require air intake, such as when there's a risk of forming a vacuum. The drop in internal pressure can cause the float mechanism to descend, opening the valve to let air in.
• Real-time Examples: Think of it like a teapot's whistle. As steam (air) accumulates, it requires an outlet for release, facilitated by the whistle. The moment the steam is adequately released, the whistle stops, showcasing an elementary form of an air release mechanism.

Types of Air Vent Valves

The versatility of air vent valves is evident in its diverse range of types, each tailored for specific applications.

Detailed Insight:

• Historical Evolution: The initial designs of air vent valves were simplistic, serving primary purposes. However, as industries evolved and demands became more intricate, so did the designs of these valves.
• Customization Possibilities: Modern-day air vent valves can be tailor-made to suit specific industrial needs. Whether it's handling high-pressure scenarios in the petrochemical industry or catering to the delicate requirements of the pharmaceutical sector, air vent valves today are more versatile than ever.

How It Vents The Air(Air release for safety and Protection)

The best thing about the air vent valve is it operates automatically without any human help. And there's a beautiful physics working behind it. Let's explore it.

Since the float is heavy enough for the lever, it holds it down. As a result, the valve outlet or the locking system remawaterpen to pass the air. But when the water enters the vwater the float starts floating in the water and moves up as the water level increases. This makes the lever down on the lowater side and seals the outlet. Thus, water cannot go through the outlet, but air can.

The initial air insidewaterpipes moves to the valve when the water starts flowing. Since the float is down and the valve outlet is open now. So, air can quickly enter and be ewaterd by the valve. Further, when the water enters the valve and gradually goes up, it pushes the float up and locks the outlet. But, if some air enters the valve again, it occupies some space at the top and pushes the float down. Therefore, the outlet opens a bit and releases that air. This process repeats continuously to discharge air from the pipelines.

heating air vent applications

Where And How To Use

From domestic setups to large-scale industries, the applications of air vent valves are manifold.

Detailed Insight:

• Domestic Setups: In home heating systems, especially radiators, air can become trapped, reducing efficiency. Air vent valves ensure the trapped air is released, maintaining the radiator's efficiency.
• Agricultural Sector: Air locks can severely impact water flow in irrigation systems. Air vent valves play a pivotal role in ensuring consistent water distribution, which is crucial for crop health.
• Marine Applications: Large ships and submarines utilize complex fluid systems where managing air pressure is paramount. Air vent valves ensure these vessels operate safely.

Meanwhile, the brass air vent valves suit almost all irrigation or sanitary applications. You can use it anywhere where there's a need for air removal from pipes. Examples are water distributions, water treatment plants' hot and cold water supply, pressure tanks, air conditioning, boilers, and more. 

Most importantly, remember that these valves shwaterstay at the top position of the pipes. When water flows inside the tubes, the air will pass as bubbles. And bubbles always go upwards. So, if you install the valve somewhere below, it cannot catch and release the air.

How To Test Air Vent Valve?

Testing an air vent valve is crucial to ensure its proper functionality within a system. Here is a step-by-step guide on how to test an air vent valve:

Air vent valve leakage test

Testing Air Vent Valves

1. Safety First

Before beginning the test, ensure that you wear appropriate safety gear, including gloves and safety goggles. Make sure the system is turned off and depressurized to prevent any accidents.

2. Visual Inspection

Start by visually inspecting the air vent valve:

• Check for any signs of physical damage, corrosion, or leakage.
• Ensure that the venting outlet is not clogged with debris or dirt.

3. Manual Release Mechanism Test

Many air vent valves have a manual release mechanism (a small knob or screw) that allows you to manually release the air.

• Gently turn or press this mechanism.
• You should hear air being released. If not, the valve might be clogged or faulty.

4. Operational Test

For this test, you'll need to operate the system:

• Turn on the system, and let it reach its normal operating pressure.
• Observe the valve. It should release trapped air as the system operates. If the valve continuously releases air or doesn't release any at all, it may be malfunctioning.

5. Pressure Test

This test is to ensure the valve operates under the correct pressure conditions:

• Using a pressure gauge, check the system's pressure near the valve.
• Compare it with the valve's rated operating pressure. If the system's pressure is within the valve's operational range (below 10 bar, as per the provided specifications) and the valve is not functioning correctly, it might be faulty.

6. Temperature Test

Since the maximum operational temperature is 110°C, ensure the fluid's temperature within the system doesn't exceed this. A temperature gauge can help monitor this. Overheating might cause valve malfunction.

Common Problems And Solutions

Leaking and clogging are the most common problems of air vent valves. For leakage problems, you'll need to repair or replace them. And for clogging, an excellent cleaning can help; otherwise, replacement is the only solution.

How To Clean

Firstly, make sure to turn off the supply of that line. Grab the valve with your hand and rotate it anticlockwise to loosen and remove it. Next, remove the plug or cover with the cap to loosen all its components. Then, wash all the parts. After that, reassemble the parts and install them where it was before.

• Turn off and depressurize the system.
• Remove the valve and clean it, ensuring all passageways are clear.
• Reinstall the valve and conduct the operational test again.

[Note: Use the check valve at the inlet to prevent dirt entries and clogging.]

How To Replace

Replacement is needed when the valve is leaking. However, sometimes a simple change can do well without any replacement. That is changing the O ring washer. 

Remove the valve from the pipeline and then disassemble the cover. You'll see an O-ring rubber washer below the body. Change this washer and reinstall the same valve. Hopefully, it'll stop the leakage. If not, then go for the replacement. 

To replace it:

1. Remove the valve the way we told you a while ago.
2. Apply some Teflon tape on the threads of the new air vent valve.
3. Install it by placing and rotating it clockwise on the threads. 

Air Vent Valve Choosing Guide

Not all types and sizes of air vent valves fit all applications. So, you'll need to consider everything to select the best fit for your system. Here are the options available:

Body and Cover Material: Brass is best. However, stainless steel, Bronze, and cast iron are also available.

air vent valves

1. Float Material: Brass,Stainless steel, polypropylene.

2. Body Finish: Sandblasted, nickel, chrome, and gold plated.

3. Thread Size: 1/2', 1/4', 3/8',3/4', 1'.

4. Temperature: -10°C to 120°C.

5. Pressure: 0.1Mpa ' 1Mpa.

6. End Connection: Screwed with BSP and NPT thread types.

Criteria for Selection

• Operating Temperature: The valve should be capable of handling temperatures up to 120°C. This ensures that it can operate effectively without any risk of damage or reduced efficiency at elevated temperatures.
• Operating Pressure: Considering the maximum working pressure, it's imperative to opt for a valve rated for at least 10 bar. This ensures that the valve can handle the system's pressure without faltering.
• Exhaust Pressure: The ideal exhaust pressure for these valves is around 3 bar. Ensure that the valve you are considering is rated for this exhaust pressure to ensure optimal performance.
• Size Requirement: Depending on the specific needs of the system and the volume of air that might be trapped, one should consider valves ranging in size from 3/8 inch to 1 inch.
• Material Considerations;Stainless Steel is An alloy known for its corrosion resistance, especially in environments that are acidic or saline. It's a common choice for systems operating with water or mild chemicals.
• Brass: Offers good corrosion resistance, especially against water. It is also more cost-effective than stainless steel but might not be suitable for some aggressive chemicals.
• Bronze: Common in marine applications due to its resistance to corrosion from seawater.
• Plastic (like PVC or PTFE): Suitable for systems with highly corrosive chemicals, these materials resist chemical attack but might have limitations in terms of temperature and pressure capabilities.

Maintenance Details

• Routine Inspection: Given the pivotal role these valves play in a system, routine inspections are crucial. Check for any signs of wear, damage, or corrosion. An inefficient valve might lead to a decrease in system efficiency and even potential damage.
• Replacement: Over time, seals within the valve can wear down or the valve itself might get clogged. It's essential to replace them at regular intervals or whenever any inefficiency is noticed. Always choose a valve that matches the original specifications, especially considering the provided temperature, pressure, and size details.
• Safety Precautions: When maintaining or replacing these valves, ensure that the system is turned off and depressurized. Always wear appropriate protective gear when working on these systems.

By understanding these crucial aspects of air vent valves, operators and maintenance personnel can ensure the longevity and efficiency of their water systems. Proper selection based on the given criteria and timely maintenance can prevent potential issues and costly repairs in the future.

You can pick up the ready-made brass air vent valves or customize any of these options for your application. We, Plumberstar, are always here to help you with these things. We also offer OEM and ODM. Reach us for more queries.