Single Air Release Valve High Flow Capacity Anti Corrosion Flexible Configurations

Working Pressure:16kg/cm²
Shell Test Pressure:24kg/cm²
Seat Test Pressure:18kg/cm² 
Media:Water,Neutral Oil
Working Temperature:0-52°C

100％ Fusion Bonded Epoxy Coating for Inner and Outside Surface

 Flange Drilled According to EN1092 PN10,PN16

Size:DN50--DN200

The Invisible Problem — Air Inside a Water Pipeline

Air is the most common yet least visible problem in water distribution systems. It enters through pump suction vortices, dissolves out of solution at high points when pressure drops, is released from water during temperature changes, and is drawn in through leaking glands and valve stems. Once inside the pipeline, air accumulates at high points, forming pockets that progressively choke the flow cross-section. A 10% air pocket in a DN200 pipe can reduce flow capacity by 30% — not because air blocks the entire pipe, but because the remaining water must accelerate through a reduced cross-sectional area at higher velocity, increasing friction loss exponentially. The pump works harder, energy costs rise, and downstream pressures sag. When the air pocket suddenly shifts or collapses, the resulting pressure surge — water hammer — can fracture pipe walls, rupture flange gaskets, and destroy pump impellers. An air release valve is not an accessory — it is an essential pipeline protection device. The Model 4002 is a single air release valve engineered to automatically vent accumulated air at system operating pressure, maintaining full pipeline hydraulic capacity and preventing air-related damage.

Product Overview

The Model 4002 is a flanged single air release valve with high flow capacity, PN16 rated, DN50–DN200. Designed for automatic venting of accumulated air from water and neutral oil pipelines under pressure, the 4002 uses a float-operated mechanism: as air accumulates in the valve body, the water level drops, the internal float descends, and the orifice opens to release air. When water rises and lifts the float, the orifice seals closed — fully automatic, no external power, no operator intervention. The body is cast from EN-GJS-500-7 (GGG50) ductile iron with 100% fusion bonded epoxy coating (internal and external, minimum 250 um DFT, spark-tested). Internal components are corrosion-resistant materials for reliable long-term operation without sticking or leaking. Flanges are drilled to EN1092 PN10/PN16 for universal European pipeline compatibility. Manufactured by Shandong Huaze Valve Co., Ltd. (ISO 9001, since 1998), every air valve is hydro-tested at 24 bar shell pressure and 18 bar seat pressure before dispatch.

How Air Harms a Pipeline — And How the 4002 Prevents Each Problem

Key Features

High Flow Capacity — Handles Real-World Air Volumes

The 4002 is engineered with a generously sized orifice and float mechanism designed for high-volume air release. In a water distribution system, air accumulates continuously — dissolved air comes out of solution at every pressure drop, at every temperature rise, at every high point in the landscape. A small-orifice air release valve may be adequate for a short, straight pipeline; the 4002's high-flow design is specified for long transmission mains, large-diameter distribution networks, and pump discharge applications where air volumes are measured in litres per minute, not millilitres. The float-operated mechanism opens fully when the water level drops, providing the maximum possible orifice area for air release until the water rises and seals the valve.

Anti-Corrosion Construction — Reliability in Demanding Service

An air release valve operates at the air-water interface — the most corrosive zone in any pipeline. The repeated wetting and drying, the oxygen-rich environment, and the potential for chemical concentration at the interface all accelerate corrosion. The 4002 addresses this with multiple layers of protection: (1) the ductile iron body receives 100% internal and external FBE coating at 250 um DFT, spark-tested to verify pinhole-free coverage; (2) internal float and orifice components are fabricated from corrosion-resistant materials that will not rust, pit, or seize even after years of cycling at the air-water interface; (3) the float itself is designed to remain buoyant and dimensionally stable — a corroded or waterlogged float is the most common failure mode in air valves, and the 4002's material selection specifically addresses this risk.

Flexible Configurations — One Valve, Multiple Applications

The 4002 is offered with flexible configuration options to match specific installation requirements. The orifice size can be specified to match the expected air volume. The outlet connection can be configured to vent directly to atmosphere or to be piped away to a safe discharge location. Optional accessories — such as a downstream isolation valve for in-service maintenance, a hood or screen to prevent insect and debris ingress through the vent port, or a back-flushing connection — allow the 4002 to be configured for the specific demands of the installation without specifying an entirely different valve model. This flexibility is particularly valuable for EPC contractors and water utility standardisation programs where a single approved valve model must serve across multiple site conditions.

Fully Automatic Float Operation — No Power, No Signal, No Operator

The 4002 operates on a single physical principle: buoyancy. When air enters the valve body, the water level drops, the float descends under its own weight, and the orifice opens — air vents to atmosphere. When water rises back to the valve, the float lifts, sealing the orifice against the seat — no air escapes, no water leaks. There is no electrical actuator, no control signal, no solenoid, no SCADA integration — the valve responds directly to the presence of air in the body. This makes the 4002 inherently reliable: no power supply to fail, no control system to lose communication, no operator to forget to open or close a valve. It is installed, commissioned, and then operates silently and automatically for years. The only inspection required is periodic visual confirmation that the vent port is clear and the valve is not leaking water (a sign that the orifice seal needs cleaning or replacement — a simple maintenance task).

Ductile Iron Body — Built for Buried and Exposed Service

Air release valves are often installed in exposed locations — on top of pipelines at high points, in valve chambers, on bridge crossings, at pump station headers. These locations are subject to temperature extremes, UV exposure, accidental impact, and in some cases vandalism. The 4002's GGG50 ductile iron body provides the mechanical strength and impact resistance required for these exposed installations. 500 MPa tensile strength and 7% elongation mean the body deforms before it fractures — providing visual warning of overload before catastrophic failure. The FBE coating protects against external corrosion from atmospheric moisture, condensation, and occasional splash or spray. For buried installations where the air valve is installed in a chamber with a vent pipe to surface, the ductile iron body provides the same mechanical reliability underground as above.

DN50–DN200 — Sizing Matched to Pipeline Air Volumes

The 4002 covers DN50 through DN200 — the size range that matches the vast majority of water pipeline air release requirements. The valve size is selected based on the pipeline diameter, the expected air entrainment rate, and the allowable pressure drop across the valve at maximum air flow. A correctly sized air release valve vents air as fast as it accumulates — not faster (which wastes no water) and not slower (which allows air pockets to grow). DN50 is typical for branch mains and smaller distribution lines; DN80–DN100 for trunk mains and larger transmission lines; DN150–DN200 for large-diameter transmission mains and pump station headers where air volumes are highest. The 4002's flexible configuration — orifice size, outlet connection, accessories — allows the same model family to serve across this entire size range with consistent performance and consistent maintenance procedures.

Single Air Release Valve — What It Is and What It Does

Materials of Construction

Technical Data

Applications — Where Air Release Valves are Essential

• Water Transmission Mains: Long-distance pipelines carrying treated water from treatment plants to distribution reservoirs. These mains run over undulating terrain — every hill crest is a potential air accumulation point. Air release valves at each high point prevent air pocket formation that would reduce the transmission main's design flow capacity and increase pumping costs.
• Water Distribution Networks: Municipal distribution piping with multiple elevation changes across a city. Air accumulates at district high points, in dead-end branches, and downstream of pressure-reducing valves. The 4002 installed at these strategic locations maintains network hydraulic efficiency and prevents consumer complaints about air in tap water.
• Pump Station Discharge Headers: Centrifugal pumps can entrain air through vortex formation in the suction well, through leaking suction pipe glands, or from dissolved air released at the impeller eye. The 4002 on the pump discharge header vents this entrained air before it enters the downstream pipeline, protecting the pipeline and downstream pumps from air-related damage.
• Water Treatment Plants: Multiple processes within a treatment plant — aeration, flocculation, filtration, chemical dosing — introduce or release air into the process water stream. Air release valves at process vessel outlets and on interconnecting pipework prevent air carryover from one treatment stage to the next.
• Irrigation Networks: Pressurised irrigation systems (sprinkler, drip, micro-spray) cannot tolerate air in the distribution laterals — air pockets block emitters and cause uneven water distribution. The 4002 at mainline high points and lateral feed points ensures bubble-free water reaches every emitter.
• Fire Protection Systems: Fire mains are static for years between tests. Air accumulates through slow dissolution from the water, through small leaks that admit air when pressure fluctuates, and through incomplete venting during initial commissioning. Air release valves ensure the fire main is fully charged with water, not air, when the fire pump starts — critical for immediate full-flow delivery to the fire scene.
• HVAC Chilled & Condenser Water: Commercial building HVAC water loops accumulate air from make-up water, from dissolved air release at hot spots (chiller condensers, boiler heat exchangers), and from vortex formation in cooling tower basins. Air release valves at the highest points in the riser system prevent air binding in cooling coils and maintain design heat transfer performance.

Quality Assurance

• 100% Shell Hydrostatic Test — 24 bar, 60 sec — every valve body
• 100% Seat Test — 18 bar, zero leakage at orifice — every valve
• 100% Float Buoyancy Test — Float integrity, no water ingress — every float
• 100% Float Operation Test — Full stroke, orifice opens and seals — every valve assembly
• 100% FBE Coating DFT — min 250 um, all surfaces — every valve
• 100% Spark Test — 3 kV holiday detection — every valve
• 100% Dimensional Check — Flange drilling per EN1092, body height, vent connection
• EN 10204 3.1 Material Certificates available on request

Ordering Information

About Shandong Huaze Valve Co., Ltd.

Established 1998 in Qingdao, China. ISO 9001 certified manufacturer with 100–200 employees, 300 containers annual production capacity, and USD 5–6 million annual turnover. Huaze manufactures a comprehensive range of pipeline products for water, wastewater, fire protection, HVAC, irrigation, process water, and industrial applications: Gate Valves (DIN 3352 / EN 558, BS 5163, SANS 664), Swing Check Valves — flanged and wafer (DIN, BS 5153, Silent Metallic, Silent Resilient, Corrosion-Resistant Wafer), Strainers — Y Type and T Type Basket (Quick-Release, Low Maintenance), Air Valves — Single Air Release (Model 4002), Globe Valves, Flap Valves, and Fire Hydrants. All products are individually factory-tested, coated, spark-tested, and shipped from Qingdao Port to distributors, water utilities, EPC contractors, pump OEMs, and building services contractors in 30+ countries worldwide.