Airgap AG200-009 Reverse Osmosis Air Gap, with 1/4-inch Push-in Inlet and 3/8-inch Push-in Outlet (For All Reverse Osmosis Filters)Airgap AG200 009 A reverse osmosis air gap is a critical component in maintaining a safe water supply. It prevents contaminants in the sink from flowing into the clean water supply and is required by code in most states. The AG200 009s maximum flow rate is 0. 8 gallons per minute (GPM). The maximum flow rate through this air gap is the highest flow rate above which the air gap will overflow. At maximum flow rate, the air gap is dry on the outside. The