A valved opening in the top of the highest drum of a boiler or pressure vessel for venting air.
A valve , either manual or automatic that is used to remove unwanted air from the highest point of a piping system.
Valve, either manual or automatic, to remove air from the highest point of a coil or piping assembly.
Valve in a water system that automatically vents trapped air from the system.
A fitting used to vent air manually or automatically.