Air/Vacuum Valves | Dual-Function Air Valves

At Metalsin, we specialize in providing robust flow control solutions for critical water infrastructure. Our Ductile Iron Air/Vacuum Valve (also known as a Kinetic Air Valve) is a single-chamber, single-orifice solution designed to manage large volumes of air during the filling and emptying of pipelines. Engineered for durability and precision, this dual-function valve ensures undisturbed pipeline operation and prevents structural damage caused by vacuum conditions or air entrapment.

Product Overview

The Metalsin single-chamber air valve is a double-functional device that operates fully automatically without the need for manual intervention. It is specifically designed for potable water and neutral liquid applications, ensuring the safety and efficiency of main transmission lines, irrigation systems, and fire-fighting networks.

Ductile iron air/vacuum valves, furnished with flanged end or NPT/BSPT threaded end.

Main Features & Advantages:

• Double Functionality: Expertly designed to discharge large volumes of air during pipeline filling and admit large volumes of air for vacuum relief during drainage or pump failure.
• Full Bore Design: The high-capacity full-bore body ensures maximum airflow with minimal pressure drop.
• Superior Corrosion Protection: All ductile iron components are coated with Fusion Bonded Epoxy (FBE) according to DIN 3476-1 and EN 14901, making it ideal for potable water environments.
• Durable Materials: Equipped with a high-strength ABS float and resilient EPDM rubber seals for reliable performance. All fasteners are made of stainless steel 304 (A2) to prevent environmental corrosion.
• Low-Pressure Sealing: Features a precision seat design that ensures a tight seal even at pressures as low as 0.2 bar.

Technical Standards:

• Design: Fully compliant with EN 1074-4.
• Testing: Hydrostatic shell and seat tests conducted per EN 12266-1.
• Flange Connections: Available in EN 1092-2 (PN10/16), BS4504, or ASME-150# configurations to suit international project requirements.

Working Principle

The Metalsin air/vacuum valve operates based on the aerodynamic and buoyant forces of air and water, performing two critical stages of pipeline protection:

• Air Discharge (Pipeline Filling): During the initial filling of the pipeline, the large internal float remains in the dropped position, keeping the orifice fully open. As water enters the pipe, the valve rapidly exhausts the large volumes of air that would otherwise cause air pockets and flow restrictions. Once the water reaches the valve chamber, the buoyant force lifts the float, sealing the orifice to prevent water leakage.

Air flow capacity chart of Metalsin’s ductile iron air/vacuum valves.

• Air Intake (Pipeline Draining / Vacuum Relief): If the pipeline is being drained or if a sudden pump failure occurs, the water level within the valve chamber drops. The float immediately falls away from the seat, opening the large orifice. This allows a massive volume of atmospheric air to enter the pipeline, effectively “breaking” the vacuum. This function is vital for protecting the pipeline from catastrophic collapse caused by internal negative pressure.

Note: As a double-function kinetic valve, this unit remains tightly sealed while the system is under pressure and does not vent small air pockets during normal operation. For triple-function requirements (including micro-venting under pressure), please refer to our Combination Air Valve series.

Drawings & Dimensions

The typical drawing of a ductile iron flanged air/vacuum valve: 1 – Body (D.I.); 2 – Bucket (D.I.); 3 – Float (ABS); 4 – Seat (NBR); 5 – Internal Cover (D.I.); 6 – Bolts (A2); 7 – External Cover (D.I.); 8 – Bolts (A2).