Air management is one of the most overlooked aspects of water network design — until it isn't. Trapped air pockets in a pressurised pipeline cause reduced flow capacity, inaccurate pressure readings, surging, and in worst cases, pipe collapse during draining. Getting the right air valve in the right location is a small line item with an outsized impact on network reliability.
At Viadux, we supply the Bermad air valve range across civil, industrial and irrigation applications nationally, backed by our branch network in Darwin, Perth, Adelaide, Melbourne, Sydney, Gold Coast and Townsville. This guide walks through the three core categories — automatic (single orifice), combination (dual orifice), and specialised wastewater valves — so you can specify with confidence.
Why Air Valves Matter in a Pressurised Network
Every pipeline accumulates air, whether from initial filling, dissolved gases coming out of solution under pressure changes, or air drawn in during maintenance. Left unmanaged, that air:
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Reduces the pipe's effective cross-section, cutting flow capacity
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Creates pressure surges and water hammer as air pockets move and collapse
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Causes biased pressure readings, throwing off pump and valve control logic
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Risks pipe collapse during draining if air can't enter fast enough to equalise pressure
Air valves are placed at high points, long straight runs, and changes in gradient to release trapped air automatically — without needing manual intervention.
Automatic Air Valves (Single Orifice)
The A30 and A31 Automatic Air Valves are Viadux's entry point for continuous, small-volume air release in pressurised lines. As we explain on our air valves product range, these BERMAD valves are high quality automatic air release valves that allow efficient release of air pockets from pressurized pipe lines, with an advanced design that provides protection against air accumulation with improved sealing in low pressure conditions.
They're a single-orifice design, meaning they're built for ongoing micro-release rather than high-volume filling or draining events. The A30 is typically used in close proximity to control valves and water meters and in pipelines across Australia, releasing accumulated air from pockets in pressurised pipe to prevent biased readings and inaccurate pressure regulation.
Key specifications:
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Pressure rating: PN16, operating across 0.1–16 bar
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Body material: glass-reinforced plastic, with operating water temperature up to +60°C
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Available with DN20 and DN25 inlets with BSPT threaded male connections, and a sideways outlet
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Dynamic sealing prevents leakage under low pressure conditions — 1.5 psi (0.1 bar) for the A30, and 0.8 psi (0.05 bar) for the more sensitive A31
Best suited for: smaller diameter lines, locations near control valves and meters, and any application where the priority is continuous fine air release rather than handling large air volumes during filling or draining.
Combination Air Valves (Dual Orifice)
When a line needs to do more than trickle-release air — when it also has to evacuate large air volumes during filling and admit air quickly during draining — a combination valve is the right call. Viadux stocks three combination models, each suited to a different scale or application.
C30 Combination Air Valve
The C30 sits at the smaller end of the combination range. It's a high quality combination air valve for a variety of water networks and operating conditions across Australia, evacuating air during pipeline filling, releasing air pockets from pressurised pipes, and enabling large volume air intake when a network is draining. With its aerodynamic design, double orifice and optional Surge Protection device, it protects against air accumulation and prevents vacuum formation, with improved sealing in low pressure conditions.
C30 valves are used across water and residential networks, desalination plants, road and river crossings, and near control valves and water meters.
Key specifications:
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Pressure rating PN16, operating range 0.1–16 bar, water temperature up to +60°C
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Body material: glass-reinforced plastic
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Available from DN20 to DN80, with DN50 male BSP threaded connections and DN50/DN80 flanged options
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A threaded side outlet (2"; DN50) allows connection of Surge Protection (SP) or Inflow Prevention (IP) devices
C70 Combination Air Valve
The C70 is Viadux's heavy-duty combination valve, built for larger mains, pumping stations and applications where surge control matters as much as air release. It's designed for pumping stations, deep well pumps, pipelines and water networks, evacuating air during filling, releasing pockets under pressure, and enabling large volume intake during draining. The double orifice and Surge Protection (anti-slam / slow closing) device protect against air accumulation, vacuum formation and pressure surges, while minimising water spraying during air release. It is fully WSAA appraised and accredited to AS4956, AS4020, AS4158 and AS4087.
Key specifications:
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Available from DN50 to DN250 inlet, in PN16 or PN35 pressure ratings
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Body material: cast ductile iron with fusion bonded epoxy coating (blue)
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Three optional outlet configurations — sideways, downwards, or a circular surround "mushroom" configuration — that can swivel 360°
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Additional features available include Inflow Prevention (C70-IP) and Surge Protection (C70-SP)
Best suited for: trunk mains, pump stations, and any application where water hammer and surge protection are a real risk alongside standard air management.
C50 Sewage & Wastewater Combination Air Valve
Not every air valve application is potable water. The C50 is purpose-built for dirtier, more aggressive environments. It is used across Australia in sewerage, pumping stations and wastewater networks, evacuating air during pipeline filling and increasing intake during draining, providing protection against air and gas accumulation and vacuum formation.
Key specifications:
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Available from DN50 to DN100 inlets
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Body material options: glass-reinforced nylon (C50-P), ductile iron (C50-C), or grade 316 stainless steel (C50-N)
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Operating pressure range 0.05–16 bar, water temperature up to +60°C
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Inflow Prevention, Surge Protection and drainage valve options available on request
Best suited for: sewer rising mains, wastewater pump stations, and any application where the air valve needs to handle gas accumulation and corrosive conditions, not just clean water.
VS-4 SMARTVALVE Combination Air Release Valve
Alongside the Bermad range, Viadux also stocks the VS-4 SMARTVALVE Combination Air Release Valve as part of our combination air valve offering — worth discussing with our team if you're comparing combination options across brands for a specific project.
Single vs Dual vs Combination — At a Glance
Specifying the Right Valve
The right choice comes down to four questions: What's the pipe diameter and pressure class? Is this a potable, wastewater, or industrial application? Does the location need surge or inflow protection? And is the priority continuous fine release, or handling large air volumes during fill and drain events?
With 120 years in the Australian water infrastructure sector and Bermad air valves stocked across all our branches, Viadux can help you match the valve to the application — whether that's a single A30 near a meter or a fully accredited C70-SP on a major trunk main.
Need help specifying air valves for your project? Contact your nearest Viadux branch or call 1300 VIADUX (842 389) to speak with our team, ordownload the full Viadux Product Range Guide for the complete valve and pipeline product range.