Automatic air release valve for dry / pressurized risers Automatic air release valve is generally installed in systems for dry risers, but can also be used in wet systems such as pressurized risers, automatic sprinkler systems and systems for indoor fire hydrants. Float in hard rubber to withstand high pressures. Air in the system is evacuated through the ventilation hole when it is charged with water until the water reaches the float chamber. The float is then pressed upwards and seals the ventilation hole. Maximum working pressure 12 Bar. Maximum test pressure 20 Bar.