High-capacity, single-chamber automatic air valve with triple function: air supply when emptying, air release when filling, and automatic venting during operation. DN 50–200, PN 10/16/25. The DUOJET® name derives from its two stages (DUO) and the high critical air velocity achieved (JET) — considerably higher performance than conventional double-chamber air valves in compact dimensions. Air-release velocities up to sonic speed. Available in four variants (standard, P high-performance, S with shut-off, T tamper-resistant) plus BEV buried venting sets for underground installation.
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▸ Key Features
Common to All DUOJET® Variants
- Triple function: air supply (emptying), air release (filling), automatic venting (operation)
- Single-chamber design — compact dimensions with higher performance than double-chamber valves
- Stabilised float body prevents pull-in at high air-release velocities
- Safe and reliable operation at air-release velocities up to sonic speed
- Corrosion-proof stainless steel inner parts (DN 50: inner parts made of plastic)
- Outlet female threaded acc. to DIN ISO 228; flange end acc. to EN 1092-2
DUOJET®-P — High Performance
- 40% higher performance than standard air valves
- Full-bore design — inlet, passage, and outlet flow area equal to nominal diameter
- Integrated stainless steel ball valve (3/8″ connection) for flushing, sampling, or pressure gauge attachment — standard feature
DUOJET®-S — With Shut-Off Valve
- Integrated shut-off valve for in-service inspection and maintenance
DUOJET®-T — Tamper Resistant
- Special tamper-resistant strainer and bonnet design according to DIN standard
BEV — Buried Venting Set
- Complete venting set: VAG DUOJET® air valve + protective jacket pipe
- Sturdy stainless steel jacket pipe for underground installation
- Above-ground or underground installation in a special surface box
- High cost savings due to chamber-less installation
- Also available as BAIO® BEV with boltless BAIO® connection system
▸ Technical Specifications
| Parameter | DUOJET® / P / S / T | BEV |
|---|---|---|
| Valve type | Single-chamber automatic air valve, triple function | DUOJET® + protective jacket pipe (venting set) |
| Nominal diameters | DN 50 – 200 | |
| Nominal pressure | PN 10 / 16 / 25 | |
| Outlet thread | Female threaded acc. to DIN ISO 228 | |
| Flanges | EN 1092-2 | |
| Air-release velocity | Up to sonic speed | |
| Installation | Above-ground | Underground (chamber-less) or in surface box |
▸ Materials
| Component | DUOJET® Standard / T | DUOJET®-P / S | BEV |
|---|---|---|---|
| Body | Ductile iron EN-GJS-400-15 (GGG-40) | GGG-40 (valve) + SS jacket pipe | |
| Bonnet | Ductile iron EN-GJS-400-15 (GGG-40) | ||
| Inner parts | Stainless steel 1.4541 (DN 50: plastic) | ||
| Float | Stainless steel A4 (DN 50 PN 10/16: synthetic; from PN 25: A4) | Plastic | Per DUOJET® variant used |
| Sealing | EPDM | ||
| Bonnet bolts | Stainless steel A4 (DIN EN ISO 3506) | ||
| Jacket pipe (BEV) | — | Stainless steel | |
| Coating | Internally and externally epoxy coated (min. 250 µm) acc. to GSK guidelines | ||
▸ Available Variants
| Variant | Description |
|---|---|
| DUOJET® Standard | Triple function air valve; stainless steel float; standard compact design |
| DUOJET®-P | High-performance: 40% higher capacity than standard; full-bore design; plastic float; integrated SS ball valve with 3/8″ connection |
| DUOJET®-S | Standard air valve with integrated shut-off valve for in-service inspection and maintenance |
| DUOJET®-T | Tamper-resistant: special strainer and bonnet design acc. to DIN standard |
| BEV Venting Set | DUOJET® air valve + stainless steel protective jacket pipe for underground chamber-less installation |
| BAIO® BEV | BEV venting set with boltless BAIO® connection system for faster underground installation |
▸ Operating Principle
1. Air Supply (Pipeline Emptying)
When the pipeline is being emptied, a pressure difference is generated. The shut-off device and the float drop into open position due to their own weight, allowing air supply to prevent pipeline collapse.
2. Air Release (Pipeline Filling)
When filling, the air inside is released via the large cross-section. The valve design prevents the shut-off device and float from being pulled into the seat by the airflow. As water rises, the float moves into the final closing position.
3. Automatic Venting (During Operation)
During operation, accumulated air lowers the water level and the float drops, releasing the small vent opening. Air flows out at high speed while water refills, causing the float to rise and close the vent again.
▸ Applications
- Water treatment
- Water distribution — pipeline networks, pressure zones
- Dams and reservoirs
- Power plants
- Industry
- Pressure management
- Underground/buried pipelines (BEV variants)