The thermostatic air vent contains a welded stainless steel thermal element that expands when heated and contracts when cooled. When air and non-condensable gases are present, the valve is in the open discharge position. When steam reaches the air vent, the element expands and closes the valve off tightly.
Air Vents are installed at the end of steam mains as well as other high points in the system. The Air-Vent reacts to temperature changes and is OPEN when cooler air is present and CLOSED when hot steam enters the system.