Netafim Combination Air/Vacuum Relief and Continuous Acting Air Vent, 2 Inch (65ARIB2PP)Netafim Combination Air Vacuum and Continuous Acting Air Vents Proven design provides more air release capacity than other vents of similar size. Applications 1 and 2 Combination Air Vacuum and Continuous Acting Air Vents For discharge and intake of large volumes of air at pump and filtration stations, along mains and at the end of mainlines. For continuous air release at high points in pipe network or upstream of manifolds. Every 1,500 feet along