... Nominal pressure: PN0.6-1.6MPa Nominal diameter:DN80-200mm Double Orifice Air Valve SPECIFICATION:Standard: GB, BS, ISO,, DIN, AWWASuitable temperature ... one is used to intake and release large amount of air and the small one is used to release the ... air during the course of water supplying. The main pipeline is DN400-1600mm. Double Orifice Air Valve