Air Release Valve | Air Venting Valve

General Introduction

Metalsin provides high-performance automatic air release valves (commonly referred to as air venting valves) engineered for water supply, drainage, and wastewater treatment infrastructure. Unlike standard kinetic valves, our lever-type air release valves are designed for high-precision air management under operational stress. The advanced high-leverage mechanism allows the float to reliably open the orifice even at high working pressures (up to PN16/25/40), ensuring that pipelines maintain maximum flow efficiency by continuously purging entrapped air pockets that would otherwise restrict hydraulic capacity.

Ductile iron air release (air venting) valves; liquid epoxy coating for various applications: blue, green, red; furnished with NPT or BSPT threaded ends

Designed for durability and compliance, these valves feature a robust ductile iron body and cover, with all internal components—including the lever, seat, and float—meticulously crafted from 304 stainless steel. To ensure long-term corrosion resistance and safety, all surfaces are finished with FBE or liquid epoxy coating compliant with NSF 61 & 372 standards. Available in 1/2″, 3/4″, and 1″ threaded sizes, the valves support a maximum working pressure of 16 bar (with a 24 bar shell test and 17.6 bar sealing test) and an operating temperature range of -10°C to 80°C. For optimal performance, these valves should be installed at the pipeline’s highest points via a threaded nipple connection to maintain system integrity.

Working Principle

The automatic air release valve is specifically designed to purge entrapped air from a pipeline while the system is operating under pressure. Its functional cycle consists of the following stages:

• Air Collection: As pressurized water flows through the pipeline, dissolved air is released and migrates to the high points of the system where the air valve is installed.
• Displacement of Water & Float Descent: The accumulating air gathers at the top of the valve body, displacing the water and causing the internal liquid level to drop. As the water level falls, the ball float loses buoyancy and descends due to its own weight.
• Lever-Actuated Venting & Resealing: The downward movement of the float acts upon a lever mechanism. This leverage amplifies the force needed to overcome internal pipeline pressure, pulling the sealing button away from the small orifice to allow air to escape to the atmosphere. Once the air is vented, the water level rises again, lifting the float and driving the lever to reseal the orifice, ensuring a leak-proof closure.

Technical Drawing, Materials & Dimensions

Technical drawing of ductile iron air release (air venting) valve.