Custom GGG40 Air Valve Supplier & Manufacturer

GGG40 (EN-GJS-400-15) ductile iron possesses a nodular carbon graphite structure providing a minimum tensile strength of 400 MPa and elongation ≥15%, compared to GG25 gray iron's 250 MPa tensile strength and near 0% elongation. Air valves are frequently exposed to transient hydraulic water hammer, pressure surges, and external ground frost heave. GGG40 prevents catastrophic brittle fracture under these severe dynamic loads, making it the mandatory standard for modern municipal water infrastructure.

Single-Function (Air Release) Valves feature a small orifice designed strictly to exhaust small pockets of entrained air while the pipeline is under operating pressure.
Double-Function Valves combine large orifice air intake (vacuum breaking) and large orifice air discharge during pipeline draining and filling operations.
Triple-Function (Combination) Valves integrate all three capabilities in a unified housing: rapid large-volume air discharge during main filling, continuous small-orifice air release under full working pressure, and rapid high-capacity air intake during power failures or draining to prevent line collapse.

During rapid pipeline filling, high-velocity air escapes through the air valve's large orifice. When the water column reaches the valve, it slams the floating mechanism shut against the seat, creating severe local pressure spikes (water hammer). An anti-slam mechanism features a secondary spring-loaded or kinetic disc that automatically throttles air discharge velocity once air pressure exceeds a critical differential threshold. This creates a cushion of compressed air that decelerates the advancing water column prior to closure.

Air valve sizing depends on two main design calculations:
1. Filling Air Discharge Requirement: Based on maximum pipeline pump discharge rate ($Q$). The valve orifice must discharge air at an equivalent volumetric flow rate without creating excessive backpressure ($P_{diff} \le 0.3 \text{ bar}$).
2. Draining Vacuum Intake Requirement: Calculated using gravity flow rates during main burst or drain valve opening ($Q_{drain} = C_d \cdot A \cdot \sqrt{2gH}$). The vacuum relief orifice must admit sufficient air to maintain internal pipe pressure above atmospheric collapse limits ($P_{vac} \ge -0.35 \text{ bar}$). Generally, an air valve nominal diameter (DN) should be 1/8th to 1/10th of the main carrier pipe diameter.

Yes, but standard clean water air valves should never be installed in sewage lines because solids, grease, and sludge will clog the upper orifice mechanism. For wastewater service, KR Valve manufactures customized GGG40 Wastewater Combination Air Valves featuring an elongated conical lower body. The conical body maintains a deep air cushion that isolates the liquid media and solids at the bottom, keeping the upper stainless steel float levers and resilient seals clean and operational.

Our standard GGG40 air valves feature non-toxic electrostatically applied Fusion Bonded Epoxy (FBE) powder coating compliant with DIN 30677-2 and AWWA C550, with a minimum dry film thickness of 250 microns. All internal elastomeric seals (EPDM) and plastic internal components hold WRAS, KTW, and NSF-61 international drinking water compliance certificates, ensuring zero taste, odor, or chemical leaching into potable water networks.

KR Valve offers extensive custom manufacturing capabilities: private label branding/casting logo integration, customized flange drilling standards (EN 1092-2, ANSI B16.5, BS 10, JIS), high-pressure ratings up to PN40 / Class 300, special internal float materials (316L Stainless, Duplex 2205), high-temperature Viton sealing elements, and custom anti-surge kinetic internal mechanisms designed to customer pipeline hydraulic modeling input.

Under normal operating conditions, GGG40 air release valves should undergo visual inspection and manual flushing annually. Isolate the valve using an inline gate or ball valve beneath the inlet, vent system pressure using the test plug, remove the top cover bolts, clean internal stainless steel float guides, inspect the resilient EPDM nozzle seat for particle debris, and verify smooth vertical float movement before re-torquing bonnet fasteners to specification.