What is an Air Vent Valve?

In this blog post, you’ll read:An air vent valve is very much popular as a safety device. It releases air into the water supply piping system to avoid air-related problems. The air vent valves have an automatic mechanical design and can control and maintain pressure without any help from an operator.
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An air vent valve is very much popular as a safety device. It releases air into the water supply piping system to avoid air-related problems. The air vent valves have an automatic mechanical design and can control and maintain pressure without any help from an operator. The air vent valves are made of brass. The internal apparatuses, such as the small levers and springs, are made of stainless steel. The area of air vent valve usage is relatively low temperatures. These valves’ highest pressure designed and dimensioned for is 10 bars.

Types of Air Vent Valves

  • Float type: This air vent valve releases air in the piping nonstop.
  • Float type quick ventilation: It dissipates a large quantity of air upon system startup and discharges accumulated air continuously.
  • Float type vacuum breaker: This air vent valve takes in air to lessen vacuum conditions and releases accumulated air if any.

The difference between air vent valves with and without a quick exhaust mechanism seems to be during the operation at low pressure up to 0.015 megapascals. By exhausting a large amount of air from the piping at low pressure, the valve confirms a smooth initial water supply.

air vents
air vents

Purpose of Brass Air Vent Valve

  • To protect piping & sanitary materials from corrosion due to air (oxygen)
  • To protect against water flapping at the faucet due to air.
  • To protect against noise caused by the entrance of air into cold/hot water supply systems, air conditioning systems, and other systems.
  • To smooth startup and steady operation of water supply and other systems/devices through air discharge during primary water conveyance.

Technical Specification & Product Description of Brass Air Vent Valve

Standard size1/2″, 3/4″, 1″
ThreadISO228, ISO7/1
Working Pressure1.6Mpa
Tested Pressure1.0Mpa By Gas
Working MediumGas, water
Working Temperature-20° C≤ T≤ 120° C

The main parts of an Air Vent Valve are:

  • Cap
  • O-ring
  • Closing Apparatus
  • Main body
  • Plug
  • Pin
  • Float 
air vent valve specs
air vent valve specs

Brass Air Vent Valve Materials

ComponentsMaterials made of
StrainerStainless Steel
BodyNickel Plated Brass
FloatPolyethylene resin
Disc AsslyBrass

Installation of Brass Air Vent valve

Perfect installation is complicated for the operation of air vent valves. These valves are designed to exile air from the piping system; they should be located where the air is most likely to collect. You should install them at system high points in the vertical position with the inlet down.

The air vent valves remove the air that gathers in heating and air conditioning systems. Due to the powerful presence of oxygen inside the piping, galvanic corrosion occurs. This corrosion effect can be reduced by using brass. Moreover, these valves permit to adjustment of the heating and cooling power. They avoid the creation of air pockets inside radiators and fan coil units. The air vent valves have to be installed in a vertical position only. These should be set on top of each system. It would be easily identified whether the air pockets are formed or not by checking distribution manifolds, riser pipes, etc. The airflow of these valves increases following the working pressure of a system. When the pressure rises to 6 bar, the airflow increases to a maximum figure. The presence of air in a heating system causes a fall in its efficiency.

air vent drain valves
air vent drain valves

How does an Air Vent Valve Work?

When liquid is driven through the system initially, the primary air inside the piping is pushed into the air vent by the pressure of the flow. The float rests in the air vent’s lower part, allowing the valve to stay open and continuously discharge air.

After the primary air venting, liquid flows into the air vent. The float increases with the rising liquid and closes the valve.

The liquid level drops if air enters the vent while it is closed. As a result, the float lows down & allows the valve to open and discharge air once more.

Air in the pipeline comes from 3 initial sources:

  • The pipeline itself: Before starting, a pipeline isn’t theoretically empty. It’s always filled with air. The air must be exiled until the pipeline is filled with any fluid.
  • Fluid pumped: Water always holds 2% air by volume. Adhesives or other dense fluids can trap air in pockets; when the fluid moves through the system, air separates from that fluid.
  • Mechanical equipment: Air enters the system through pumps, packing, valves, and pipe joints.

When air is permitted to store in pumping systems, the risk of damage to mechanical equipment is high. Sometimes efficiency will also be sacrificed. Applying air vent valves might be a good start if a pumping system faces pressure surges and lowered efficiency.

air vent dimensions
air vent dimensions

Application of a Brass Air Vent valve

  • Hot and cold water supply system
  • Boiler
  • Solar water system
  • Air cooling & conditioning system
  • Water heater appliance
  • Pressurized water flow system
  • Other different devices

Precautions for Installing Brass Air Vent Valve

Before installing the air vent valve, you should carefully wash the inside of the piping to remove dirt & scale. The application position of the sealing agent or where to attach seal tape is much more critical at the connection time. When connecting the product to piping, we should pay attention to this. The valve shouldn’t be disassembled. You should prepare enough space for inspections, maintenance, and repairs. Installing the product under the roof or inside the wall is terrible. The vertical installation will provide you with the maximum feedback. This air vent valve should be fixed where air tends to accumulate. We can use a stop valve-like gate valve, ball valve, etc., for maintenance and inspections if needed. When the atmospheric temperature becomes low, you should drain water. Otherwise, water is not to be used for an extended period.

from Caleffi Hydronic Solutions

Air Vent
Air Vent

Advantages of using Brass Air Vent Valve

Air vent valves defend the pipeline system and maintain its efficiency. These valves are faultless for quickly venting large volumes of air during filling or startup. They also permit air back into the piping system during discharging. It is significant because pipe materials can cause failure under negative pressure. 

Disadvantages of using Brass Air Vent Valve

If a pipeline is occupied or emptied too quickly, an air vent valve does not always meet the airflow demands. You must size the valve properly for the respective application.

Brass Air Vent
Brass Air Vent

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