What is air release valve for water and Why Do We Use Them?

This piece describes how air release valves operate within water systems to enable operators and users of air release valves to understand its operation and importance in pipeline systems.

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What is the function of an air release valve? 

An air release valve is typically used in water or irrigation schemes to ensure that any entrained air in the water system is automatically released in order to maximize the system performance. Entrained air pockets in pipes can cause excessive head loss and flow reductions if air is not effectively released.

The air release valve is also used during pipe drainage maximising the exiting outflow of water and at the same time ensuring the pipe is not subject to vacuum conditions.

It’s also designed to automatically release any entrained air that accumulates at the high spots during water transfer, maximizing the pipeline efficiency.

Finally, air valves have potential to generate water hammer under column separation conditions or excessive high fill rates of the pipe. Valves fitted with RFP (rapid filling prevention) designs ensure that the pipe cannot be filled at an uncontrolled rate that would induce water hammer.

Watch the following animation to see this function in action:

What are the main components of an air release valve?

• Valve body
  The unique ductile Iron valve body is compact and houses the inner floats and upper mechanism. The body is designed so that the inlet is completely free of float guides, therefore enabling butterfly valves to be used directly under the air valve without impacting performance. Each valve body has a lower 316SS grade tamper proof drain valve enabling the valve to be drained and tested quickly and safely.
• Inner float assemblies
  The inner floats are all manufactured from bar stock polypropylene which ensures they cannot ever change their mass or shape. The floats are all guided and kept square to the body by the four guide ribs on the valve body ensuring they cannot get blown offset to the side.

  The CSA Fox-RFP air valve design incorporates a multitude of elements to assist in the work to produce a combination air valve with rapid filling prevention.

The three floats assist in producing the three-general functions:

1. Large orifice float
   This enables air inflow and discharge during filling and drainage.
2. Small orifice float
   The small orifice float houses the nozzle subset, ensuring that the valve automatically releases any entrapped air when the pipe is full, and an air pocket presents itself in to the valve.
3. RFP upper float
   During pipe filling this float will remain open to fill the pipe at a controlled rate. If the exit flow rate exceeds a safe working rate, it immediately rises and chokes the air discharge to a safe operating rate, avoiding water hammer.
4. Upper seat
   The 316S grade stainless steel seat cleverly houses the O rings that make the seal between the seat and float.
5. Mesh outlet and cover
   The valve has a stainless-steel mesh that prevents any possibility in external contaminates fowling the inner floats and keeps vermin and spiders away from the underside of the cover. The ductile cover is robust and keeps any direct sunlight away from the floats and is strong enough to be stood on if fitted inside a valve pit.

How to operate the air release valve

The following animation highlights the features and benefits plus the operation of the air release valve functions described above.

Looking for additional support? We’re here to help.

Here at Bermad, we’re committed to providing the information you need for products, technology, and operating systems. That’s why we’re committed to ensuring that users of the CSA air-valves have the best information on the functions of all our products.

Please see a short video on how to clean and maintain the CSA Fox-RFP air valve in the field:

If you have any further questions, require additional details, or wish to discuss any technical aspects of the air release valve, you can:

1. Visit the Fox-RFP valves page where all the data is present including data sheets, engineering assistance, 2D &3D cad drawings, manuals, case studies, spare parts, operational videos.
2. Visit the Bermad training facility to get hands on training on the pressure reducing valve
3. Contact our nearest sales office for discussions with the trained Bermad personnel.
4. Use our live field support to assist in the operation of any valve.

If you wish to get hands on experience when it comes to the air release valve, you can visit the nearest Bermad training facility for an in-person demonstration.

Choosing the right location for the installation of an air valve is very important. To obtain maximum efficiency, the air valves are placed at strategic locations on the pipeline’s run. For proper aeration and ventilation of water and wastewater systems, air valves are required at the following points:

Maximum High Points

The company is the world’s best air release valve for water supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

Air bubbles accumulate and form air pockets that get stuck at the highest points in the system. Placing air valves here helps ventilate the air pockets out to the atmosphere.
Valve Required: Air release valve / combination valve.
 

Temporary High Points

Local high points can also serve as an accumulation spot for air bubbles. An air valve here vents the bubbles out to the atmosphere.
Valve Required: Air release valve/combination valve.
 

Long Rising or Falling Pipe Sections

Dislodged air pockets can flow downstream and form larger air pockets at the top section of the pipe. Also, rapid flow in downward sloping pipe sections can form a vacuum.  As a rule of thumb, air release valves and air vacuum valves should be installed every 800m on long pipe runs to properly vent and draw air into the system.

Long Rising or Falling Pipe Sections

Dislodged air pockets can flow downstream and form larger air pockets at the top section of the pipe. Also, rapid flow in downward sloping pipe sections can form a vacuum.  As a rule of thumb, air release valves and air vacuum valves should be installed every 800m on long pipe runs to properly vent and draw air into the system.
 

After Fast Closing Valves

When valves are suddenly shut off, vacuums can form downstream from the valve due to the momentum of the flow. For proper functioning of the pipe, the negative pressure needs to be relieved by admitting air into the pipe.
 

After Flow Throttling / Boosting Devices

After flow throttling devices like turbines or control valves, the pressure and velocity differences can lead to the formation of a vacuum. Air vacuum valves are needed close to these devices to draw air into the system Flow boosting devices like pumps and reduced pipe sections also draw air bubbles into the flow. Air release valves need to be installed after these devices to vent these air pockets.

Finally, always install your air valves at accessible, well-ventilated locations. This ensures they always have enough air to draw into the systems, and the air expelled has a route out. Also, it makes it easier to reach the valves for maintenance.

Contact us to discuss your requirements of Yaxing gate valve. Our experienced sales team can help you identify the options that best suit your needs.