Double Orifice Combination Air Valve with Built-In Isolation Gate

In large-scale long-distance water supply projects and complex drainage systems, air management and maintenance accessibility are equally critical. Metalsin provides the most highly integrated air management solution: the Double Orifice Combination Air Valve with a Built-in Isolation Mechanism.

Ductile iron double-orifice combination air valves with built-in isolation mechanism

This product ingeniously integrates a high-capacity “kinetic air valve,” a high-precision “pressurized air release valve,” and a “vertical isolation gate valve” into a single valve body. This design not only significantly saves installation space but also achieves the core advantage of allowing safe maintenance without shutting down the main pipeline.

Construction Characteristics

In contrast to the standard dual-chamber series, this air valve features an integrated isolation gate positioned between the two chambers. It utilizes a three-in-one integrated design, ensuring efficient coordination of all functional modules through precision casting and machining:

• Integrated Isolation Mechanism: Located at the center of the valve body, it features a vertically rising stem and a sealing wedge. By operating the top handwheel or cap, the connection between the main pipeline and the upper air valve chambers can be cut off.
• Right-side Kinetic Chamber (Air & Vacuum): This chamber houses a high-strength large float. The top features a full-bore exhaust port, responsible for large-volume air discharge during pipeline filling and massive air intake during sudden vacuum events.
• Left-side Automatic Chamber (Air Release): This chamber contains a precision small float paired with a micro-venting orifice. It is connected to the main inlet via a transverse passage and is responsible for continuous air release during pressurized system operation.
• Premium Anti-Corrosion Body: The valve body is constructed from Ductile Iron, with internal and external surfaces coated in Fusion Bonded Epoxy (FBE). This ensures compliance with potable water standards and provides excellent corrosion resistance.

Working Principle

Metalsin’s double-orifice combination air valve with isolation gate achieves its superior protection through the following three stages:

• Initial Filling / Rapid Exhaust Phase: During pipeline filling, the isolation gate is fully open, and air is pushed toward the right-side kinetic chamber. The large float drops with the airflow, leaving the kinetic orifice fully open to exhaust massive volumes of air and prevent air pockets.
• Pressurized Operation / Micro-Venting Phase: Once the system is full, all floats rise to seal the valve ports. During operation, micro-bubbles released from the water accumulate in the left-side small chamber. When the air lowers the water level, the small float drops to open the micro-orifice, ensuring hydraulic efficiency.
• Pump Shutdown / Vacuum Relief Phase: In the event of a power failure or pipe burst, the right-side large float instantaneously loses buoyancy and drops. This opens the large orifice to admit atmospheric air, effectively breaking the vacuum and preventing pipeline collapse or joint damage.

Isolation & Maintenance Advantage

Typical drawing for the double-orifice combination air valve with built-in isolation gate, flanged end, full port design.

Traditional air valve maintenance often requires the installation of a bulky separate isolation valve (such as a butterfly valve). Metalsin integrates this function directly into the body. By rotating the central valve stem, the internal gate moves downward to press against the bottom seat, effectively cutting off the physical connection between the main pipeline and the two upper exhaust chambers. Once the internal pressure is released, maintenance personnel can safely open the left and right covers to clean the floats or replace seals and lever mechanisms, completely eliminating the need to shut down the main pump station or drain the entire pipeline. This design eliminates the need for additional valves, flanges, fasteners, and gaskets, reducing construction difficulty and potential leakage points.

Parameters & Dimensions

P-T & Standards: Working pressure: 16 bar. Hydrostatic shell test pressure: 24.0 bar; Hydrostatic sealing test pressure: 17.6 bar. Working temperature: -10°C~100°C. Design codes: EN 1074-4, AWWA C512. Epoxy coating code: AWWA C550, DIN 3476-1, EN 14901.

Material Specification: Body & Cover & Stem Cap: ductile iron ASTM A536 65-45-12, EN-GJS-450-10; Nipple & Plug: brass EN12165 CW603N; Float Ball: ABS; Seat Ring: EPDM; Stem: ss 304/316, bronze; Bolts & Nuts: A2 (TP304) / A4 (TP316).