Single Body Combination Air Valves

At Metalsin, we provide advanced flow control solutions designed to safeguard your infrastructure. Our single body combination air valve is a space-saving, “triple function” device engineered to manage air in water pipelines with maximum precision. By integrating kinetic air discharge, vacuum relief, and automatic micro-venting into a single compact unit, this valve ensures peak hydraulic efficiency and prevents catastrophic pipeline failure.

Product Overview

The Metalsin single body combination air valve is the ultimate protection for municipal and industrial water systems. Unlike traditional separate-body valves, our integral design allows for a smaller footprint and easier installation while delivering high-capacity performance.

Figure-1: The typical drawing of a single-body combination air valve for waterworks.

Whether you are managing a high-pressure transmission main or a localized distribution network, this valve automatically handles air pockets that cause friction loss and protects against the “pancake” effect (pipe collapse) caused by sudden vacuum conditions.

Working Principle: The Triple Function Logic

Our single-body combination air valve operates through a high-precision, lever-actuated mechanism to provide three critical protection phases:

• Large Volume Air Exhaust (Kinetic Phase): During the initial filling of the pipeline, the internal float remains dropped, keeping the large orifice fully open. This allows massive volumes of air to be expelled as water enters. Once the water reaches the chamber, the buoyant float rises to seal the main orifice.
• Micro-Venting Under Pressure (Automatic Phase): While the system is running under full pressure, small amounts of air will naturally come out of solution and gather at the top of the valve. As air accumulates, the water level drops slightly. The high-leverage mechanism amplifies the float’s weight to pull open a small orifice, purging the air without causing water leakage or pressure spikes.
• Vacuum Relief (Air Intake Phase): If the pipeline drains or a pump fails, the water level drops instantly. The float falls, retracting the plug and admitting large quantities of atmospheric air. This breaks the internal vacuum and prevents thin-walled pipes from collapsing.

Premium Material Options for Every Environment

Metalsin offers this single body combination air valve in three specialized materials to ensure long-term durability in any service condition:

• Ductile Iron (GGG 40/Gr.65-45-12): Characteristics: The industry standard for strength and cost-effectiveness. All ductile iron valves are finished with Fusion Bonded Epoxy (FBE) coating (min. 250μm). Best Use: Municipal waterworks, general distribution networks, and potable water systems where safety and durability are paramount.

Single-body combination air valves made of ductile iron EN-GJS-450-10.

• Stainless Steel (304/316): Characteristics: Offers superior chemical resistance and prevents surface rust. SS316 (CF8M) is particularly effective in harsher water chemistries. Best Use: Industrial water treatment, desalination plants, food and beverage processing, and moderately corrosive environments.

Single body combination air valves made from cast stainless steel 316 (CF8M).

• Aluminum Bronze (ASTM B148 C95800): Characteristics: Known for its incredible resistance to chloride-induced corrosion and its natural ability to resist biofouling (sea life attachment). Best Use: Marine environments, offshore platforms, seawater cooling systems, and coastal desalination facilities where saltwater would quickly degrade other metals.

Single-body combination air valves made of aluminum bronze ASTM B148 C95800 for seawater services.

Technical Parameters & Dimensions

Main valve components: valve body, valve bonnet, float ball, support frame, lever, plug, seat, dome, bolts and nuts. Shell test pressure: 2.4 MPa; Sealing test pressure: 1.6 MPa. Sizes: DN25 ~ DN200. Pressure rating: PN 10, PN 16. Threaded end for DN25~DN32, flanged end for DN50 and above.