What Are Air Release Valves?
Air release valves are critical components in pressurised pipeline systems designed to automatically remove trapped air from water mains, sewage networks, irrigation systems, and industrial pipelines. Air pockets within pipelines reduce water flow efficiency, cause water hammer events, and can lead to severe surge damage to pipework infrastructure.
Our air release valves maintain optimal pipeline performance by continuously expelling air during normal operation, ensuring your system runs smoothly and safely.
How Air Release Valves Work
Air Expulsion Process
As pressurised water flows through your pipeline, air bubbles naturally accumulate at the highest points. Air release valves feature a float mechanism connected to an internal valve seat. When air enters the valve chamber, the float descends, opening the valve and allowing air to escape into the atmosphere.
Water Sealing
Once air is expelled and water rises in the valve chamber, the float automatically rises and closes the valve. This prevents pressurised water from escaping while maintaining readiness to expel the next air pocket. The process repeats continuously during pipeline operation.
Types of Air Release Valves
Single Orifice Valves
Continuous air release during operation. Single orifice air release valves feature a small opening designed for steady-state air expulsion as your system operates. Ideal for pipelines where small volumes of air continuously need removing.
- Continuous air venting
- Compact design
- Simple maintenance
Double Orifice Valves
Large and small orifice combination. Dual orifice air release valves include both a large rapid-vent opening for initial air purging when filling pipelines, and a small continuous-vent opening for ongoing air removal during normal operation.
- Rapid initial air release
- Continuous venting capability
- Optimal for fill operations
Combination Air Valves
Multi-functional air management. Combination air valves integrate air release functionality with vacuum breaking to prevent dangerous pressure drops and surge events in long pipeline runs, providing comprehensive air management in a single compact unit.
- Air release + vacuum breaking
- Space-efficient solution
- Enhanced system protection
Kinetic Air Valves
Advanced velocity-responsive design. Kinetic air release valves use flow dynamics to optimise air expulsion rates, automatically adjusting to pipeline conditions. Particularly effective in high-velocity systems and dynamic pipeline environments.
- Velocity-responsive operation
- Optimised performance
- Reduced surge events
Materials & Construction
We supply air release valves manufactured from a range of premium materials to suit your pipeline environment and pressure requirements.
Cast Iron
Traditional, cost-effective option for standard water and sewage applications. Suitable for PN10-PN16 pressure ratings.
Ductile Iron
Enhanced strength and impact resistance. Ideal for higher pressure systems and industrial applications. PN25-PN40 capable.
Stainless Steel
Corrosion-resistant solution for demanding environments, coastal installations, and chemical-laden pipelines. Premium durability.
Brass
Excellent corrosion resistance and precision engineering. Preferred for smaller diameter valves and specialised applications.
Available Sizes & Pressure Ratings
We supply air release valves across a comprehensive range of sizes and pressure classifications to match your system requirements. From compact 25mm installations to large infrastructure projects exceeding 300mm diameter, we have the solution.
| DN Size | Nominal Diameter (mm) | PN10 | PN16 | PN25 | PN40 |
|---|---|---|---|---|---|
| DN25 | 25 | ✓ | ✓ | ✓ | On Request |
| DN32 | 32 | ✓ | ✓ | ✓ | On Request |
| DN40 | 40 | ✓ | ✓ | ✓ | ✓ |
| DN50 | 50 | ✓ | ✓ | ✓ | ✓ |
| DN65 | 65 | ✓ | ✓ | ✓ | ✓ |
| DN80 | 80 | ✓ | ✓ | ✓ | ✓ |
| DN100 | 100 | ✓ | ✓ | ✓ | ✓ |
| DN150 | 150 | ✓ | ✓ | ✓ | On Request |
| DN200 | 200 | ✓ | ✓ | ✓ | On Request |
| DN300 | 300 | ✓ | ✓ | On Request | On Request |
| DN300+ | 300+ | Bespoke | Bespoke | Bespoke | Bespoke |
Note: Pressure ratings are expressed in PN (Pressure Nominal) classification. Standard stock availability includes PN10 and PN16 across all sizes. Higher pressure ratings and larger diameters may be supplied on request. Contact our sales team for custom specifications and bulk orders.
Typical Applications
Air release valves are essential components across diverse industrial and municipal infrastructure projects. Our solutions are proven in demanding environments worldwide.
Water Distribution Mains
Protect municipal water supply networks from air-induced pressure spikes and water hammer. Maintain consistent flow rates and system efficiency across town centre and rural distribution networks.
Sewage & Foul Water Systems
Prevent surge events in sewage transfer pipelines and pumped rising mains. Air release valves ensure reliable operation in gravity-fed and pressure-based sewage infrastructure.
Irrigation & Agricultural Systems
Optimise water delivery to farmland with efficient air removal from long-distance irrigation pipelines. Improve water pressure uniformity and reduce energy consumption in pump operations.
Fire Protection Networks
Ensure emergency water supply reliability with proper air management in fire protection systems. Air release valves maintain system readiness and response capability during critical situations.
Industrial Pipelines
From petrochemical facilities to manufacturing plants, our air release valves protect high-pressure industrial pipelines from catastrophic surge damage and operational failures.
Hydroelectric & Water Power Systems
Critical component in power generation infrastructure where water hammer prevention directly impacts asset longevity and system reliability in demanding operating conditions.
Benefits of Proper Air Management
Installing correctly specified air release valves delivers measurable advantages across your pipeline infrastructure:
Prevents Water Hammer
Water hammer — the destructive shock wave created when pressurised water strikes air pockets — can rupture pipework, damage fittings, and compromise system integrity. Continuous air removal eliminates this risk.
Protects Against Surge Damage
Sudden pressure spikes from air pockets can exceed pipe design limits, causing catastrophic failures. Air release valves maintain stable operating pressures and extend pipeline service life.
Reduces Energy Costs
Air-free pipelines deliver water more efficiently. By eliminating air resistance and pressure losses, properly managed systems require less pumping energy and lower operational costs.
Improves System Efficiency
Consistent water flow, optimal pressure maintenance, and reduced turbulence mean your system operates at peak efficiency. Upgrade projects consistently deliver 5-15% efficiency improvements.
Extends Infrastructure Life
By eliminating surge damage, fatigue cracking, and corrosion acceleration from air pockets, proper air management can extend pipeline life by 10+ years, protecting your investment.
Maintains Regulatory Compliance
Water supply and sewage regulations increasingly mandate effective air management systems. WRAS approval and BS EN 1074 compliance ensure you meet all standards.
Standards & Certifications
All our air release valves meet rigorous international standards and regulatory requirements:
BS EN 1074-1:2000
British/European standard for valves in water supply systems. Specifies design, materials, performance testing, and quality requirements for all water industry valve applications.
WRAS Approval
Water Regulations Advisory Scheme certification confirms suitability for use in UK water supply systems. WRAS-approved products protect public health and comply with The Water Supply (Water Quality) Regulations 2016.
ISO 9001:2015
Actuation Valve & Control Ltd holds ISO 9001 certification, demonstrating our commitment to quality management systems and consistent product excellence across all manufacturing and supply processes.
ISO 14001:2015
Our ISO 14001 environmental management certification reflects our commitment to sustainable manufacturing practices, waste reduction, and minimising environmental impact throughout our operations.
Air Release Valves Buyer's Guide
Selecting the Right Air Release Valve
Choosing appropriate air release valves for your pipeline system requires consideration of several critical factors. This guide helps you make informed decisions.
1. Determine Your Pressure Rating
Pipeline systems operate at different pressure ratings. Common UK water supply systems run at PN10 or PN16 (1-1.6 bar) nominal pressure. Industrial systems and long-distance transmission mains may require PN25 (2.5 bar) or PN40 (4.0 bar) rated valves. Check your system design specifications and piping material standards to confirm the correct pressure class.
2. Calculate Pipe Diameter Requirements
Air release valve sizing depends on your pipe diameter measured in DN (Diameter Nominal) classification. Available from DN25 (compact installations) to DN300+ (large infrastructure), we supply solutions for all pipeline scales. The valve port diameter should generally match the main pipeline diameter for optimal performance.
3. Choose Single vs. Double Orifice Design
Single orifice valves provide continuous air venting suitable for steady-state operation. Double orifice designs include a rapid-vent opening for fast initial air release during commissioning and filling, plus a small continuous-vent for ongoing operation. Double orifice valves are recommended for pipeline systems that require frequent filling cycles or experience high initial air release requirements.
4. Select Appropriate Materials
Material choice impacts durability, cost, and performance in your specific environment. Cast iron suits standard water systems, ductile iron provides enhanced strength for high-pressure applications, stainless steel delivers superior corrosion resistance in harsh environments, and brass offers precision engineering for smaller specialised applications. Consider water chemistry, corrosivity, and temperature when selecting materials.
5. Consider Installation Location
Install air release valves at the highest points of your pipeline system where air naturally accumulates. In systems with multiple high points, install valves at each location. Proper positioning ensures maximum effectiveness and prevents air lock situations that can compromise system performance.
6. Plan for Commissioning & Maintenance
Quality air release valves should include accessible float chambers for inspection and cleaning. Plan regular maintenance intervals to remove sediment and ensure continued reliable operation. Double orifice valves require periodic checks of rapid-vent operation, particularly after system commissioning.
7. Budget for Long-Term Value
While air release valves represent a small percentage of total pipeline capital cost, their reliability directly impacts your entire system's lifespan. Investing in quality WRAS-approved, BS EN 1074 certified valves delivers superior durability, reduced maintenance costs, and extended infrastructure life.
Common Air Valve Installation Mistakes to Avoid
- Installing at wrong pipe locations: Valves must be positioned at system high points where air accumulates. Installing on slopes or low points reduces effectiveness.
- Undersizing the valve: Using DN50 valves on DN100 mains reduces air release capacity and may permit water escape under certain conditions.
- Neglecting maintenance: Sediment accumulation in float chambers can prevent proper operation. Schedule regular inspection and cleaning.
- Mixing specifications: Don't specify PN10 valves in PN25 systems. Pressure rating must match system design parameters.
- Insufficient isolation: Install isolation valves allowing air release valve removal without draining entire mains. Essential for maintenance and replacement.