Air Valve FAQ

An air valve is a device installed on pipelines to allow air to enter or exit the pipe automatically. Air valves manage the ingress and egress of air during pipeline filling, draining, and operation, preventing air locks, reducing water hammer, preventing vacuum conditions, and protecting the structural integrity of pipes.

The main types of air valves include:

• Air Release Valves - release small air pockets during pipeline operation
• Combination Air Valves - both release air and admit air to prevent vacuum
• Vacuum Breaker Valves - allow air to enter to prevent vacuum conditions
• Air/Vacuum Valves - handle both air release and vacuum breaking
• Air Operated Valves - use air pressure to control flow in various applications

An air release valve uses a buoyant float mechanism. As water rises in the pipeline, the float rises with it, closing the discharge valve seat. When air accumulates, it reduces buoyancy, causing the float to drop and open the discharge port. Compressed air is then expelled through the orifice. Once air is released, water fills the void again, the float rises, and the valve closes, ready for the next air pocket.

Single orifice valves have one discharge opening and are suitable for small pipelines and low air volumes. Double orifice valves have two discharge openings, allowing rapid expulsion of large volumes of air and faster pipeline startup. Double orifice valves are more efficient for larger pipelines and systems with significant air accumulation, but are larger and more expensive.

A combination air valve integrates both an air release valve (for expelling air during operation) and a vacuum breaker valve (for admitting air to prevent vacuum conditions) in a single compact unit. This eliminates the need for two separate devices, saves space on pipelines, reduces installation costs, and simplifies maintenance procedures.

Pipelines require air valves for several critical reasons:

• Prevent air locks that reduce flow capacity
• Eliminate water hammer shock waves that damage pipes and fittings
• Prevent vacuum conditions that can collapse pipes
• Enable efficient pipeline filling and draining
• Reduce energy consumption by maintaining optimal flow conditions
• Extend pipeline system life and improve overall reliability

Air valves should be strategically installed at:

• All high points in the pipeline where air naturally accumulates
• Changes in gradient where pipes transition from steep to shallow slopes
• Long horizontal runs where air can accumulate over distance
• Immediately after pump discharge to release air and prevent startup problems
• Before and after large isolation or check valves
• At changes in pipe diameter
• Other strategic locations determined by system pressure and flow characteristics

Air valve sizing depends on several factors including:

• Pipe diameter - larger pipes require larger valves
• Pipeline operating pressure and flow rate
• Volume of air that needs to be expelled during filling and operation
• Rate of air accumulation in the system
• System startup time requirements and pressure transient characteristics

Contact our sales team for a detailed sizing calculation based on your specific pipeline characteristics and operating conditions.

Air valves are typically constructed from durable materials including ductile iron, cast iron, stainless steel, and brass. The choice depends on:

• Water quality and potential for corrosion
• Operating pressure and temperature
• Application requirements (potable water, wastewater, industrial)
• Specific environmental conditions

Stainless steel components are preferred for aggressive water chemistry or marine applications. All materials comply with relevant drinking water and wastewater standards.

Yes, air valves can be used in sewage and wastewater applications. However, special considerations apply:

• Valves must handle corrosive conditions and hydrogen sulfide exposure
• Materials must resist aggressive wastewater chemistry
• Discharge designs should prevent odor and gas release issues
• Integral check valves prevent backflow of contaminated sewage
• Stainless steel or coated materials are often specified for durability

Our team can recommend suitable valves specifically engineered for wastewater systems.

Water hammer is a shock wave caused by the sudden deceleration of water when valves close rapidly or pumps stop. This creates dangerous pressure spikes that can rupture pipes and damage equipment.

Air valves prevent water hammer by:

• Preventing air pockets that compress and cause shock waves
• Providing cushioning during pressure changes
• Enabling controlled filling and draining procedures
• Reducing peak pressures during system transients and emergencies

Air valve maintenance schedules depend on system conditions and water quality. General recommendations include:

• Visual inspection every 6 months to check for corrosion or damage
• Functional testing annually to ensure proper operation
• Cleaning of discharge screens every 12 months or when fouling is detected
• Complete service or replacement every 5-10 years depending on water quality
• More frequent attention in systems with poor water quality or high air volumes

Regular maintenance ensures optimal performance and extends valve life significantly.

A vacuum breaker valve automatically admits air into a pipeline when pressure drops below atmospheric levels. This prevents dangerous vacuum conditions that can:

• Collapse pipes and damage structural integrity
• Halt water flow and system operation
• Allow contaminated water to enter the system
• Cause cavitation damage to pipes and equipment

Vacuum breaker valves are essential when draining pipelines, during rapid water deceleration, or in systems with check valves that prevent backflow. They work in tandem with air release valves for complete air management.

Yes, we supply air valves suitable for potable water applications. Our valves can be specified with WRAS (Water Regulations Advisory Scheme) approval certification for UK drinking water systems. All materials in contact with potable water meet relevant health and safety standards and comply with water company regulations.

Contact our sales team to confirm WRAS certification requirements for your specific application and to ensure full compliance with water company regulations and standards.

Getting a quote is straightforward. Contact our sales team with details of your requirement including:

• Pipeline diameter and operating pressure specifications
• Pipe material (steel, ductile iron, PVC, etc.)
• Type of application (water supply, irrigation, sewerage, industrial)
• Required valve type (air release, vacuum breaker, or combination)
• Quantity needed and delivery timeline
• Any special certifications required (WRAS, third-party approvals, etc.)

Our team will provide a detailed quote and technical recommendations tailored to your specific requirements.