These valves have a cylindrically shaped polymer body with a flange connection spigot and an exhaust outlet spout for duct connection.
There is an elastic diaphragm to instantly re-establish pressure balance, a counterweight kit to keep the valve closed under normal conditions and a weather protection cover.
The special double-acting diaphragm is impervious to air and is designed to avoid blockage as well as the formation of material crusts.