Threaded Single Orifice Air Release Valve

Threaded single orifice air release valve is a compact automatic air vent fitting with internal/external thread connection, specially developed for small-diameter branch pipelines, residential water pipes and fire protection small-bore systems. Featuring a single independent exhaust hole and threaded inlet instead of flanged connection, this lightweight air valve automatically discharges trapped air inside pipelines and eliminates negative pressure during water draining, solving flow blockage, pipeline vibration and pump efficiency reduction caused by accumulated air bubbles. Its small size, easy installation and low cost make it the preferred air exhaust device for small-scale water supply projects, different from large flanged compound or double-orifice air valves used on main transmission pipelines.

Air continuously separates out from tap water during delivery and gathers at pipeline high points. Without timely venting, air pockets narrow the effective flow cross-section, raise water delivery resistance and increase power consumption of water pumps. When pipelines stop operation and drain residual water, internal vacuum will form, which may lead to pipe deformation, especially for thin plastic pipes. This threaded single orifice air valve handles both conditions fully automatically by buoyancy principle without power supply or manual control. During pipeline water filling, the internal float sinks, fully opening the single exhaust orifice to rapidly expel bulk air. After water fills the valve cavity, buoyancy lifts the float to seal the main vent and prevent medium leakage. In daily stable operation, tiny air bubbles accumulate and push the float down slightly for continuous micro venting. Once drainage creates negative pressure, the float falls again to admit outside air and break vacuum.

The whole valve body is cast from high-strength ductile iron or brass as optional. Ductile iron versions are coated with fusion-bonded epoxy resin inside and outside over 200 μm thick, anti-rust and anti-scaling and compliant with drinking water hygiene standards. Brass threaded models perform better corrosion resistance for humid indoor pipe shafts. The built-in float is made of lightweight stainless steel or solid EPDM material with stable buoyancy and no water absorption after long-term soaking. Elastic EPDM sealing gaskets are fitted at the exhaust port to realize bubble-tight shutoff under PN10 and PN16 working pressure. The top bonnet adopts threaded detachable design, allowing quick disassembly for sediment cleaning without cutting off pipeline water supply. Standard thread types include BSP and NPT to match mainstream small pipe fittings worldwide.

Main specifications cover DN15, DN20, DN25, DN32 and DN40 threaded sizes, suitable for small branch pipelines with low to medium flow. Applicable media include domestic tap water, fire-fighting water, landscape circulating water and low-corrosion neutral wastewater within working temperature 0℃–80℃. Each finished valve passes strict shell pressure test at 1.5 times nominal pressure and air tightness inspection before delivery to guarantee no seepage under full pipeline operating pressure.

Thanks to threaded connection design, workers can directly screw this valve onto pipe tees, vertical risers and pipeline peak points without extra flanges, transition joints or welding procedures, greatly shortening construction time and lowering installation costs. It is widely applied in residential building water supply pipes, indoor fire protection piping, small garden irrigation pipelines, hotel and commercial building plumbing systems. Compared with flanged air release valves, it occupies less installation space and requires fewer auxiliary accessories, perfectly matching miniature pipeline systems. By removing trapped air and balancing internal pipe pressure, this threaded single orifice air release valve optimizes water delivery efficiency, reduces equipment wear and extends the service life of small-bore fluid transportation systems.