I work 8-5, so yes, I realize apple is open during these hours. I know they are open until roughly 6 or 7pm. It's the after 5pm hours, and sat/sun hours I'm interested in. So I can plan my week.
An air gap for a dishwasher is a requirement set forth by local plumbing codes. It is a device designed to ensure water flows only in the right direction during the dishwasher cycle. As a dishwasher operates, hot water flows in from the sink's hot water connection.
The concept in an air gap, or equivalent, is a fall through open space. The DW drain water gets pumped UP (in the hose) and it has to fall down after that, by gravity. Air is necessary for the fall to occur. This pumped water falls into your drain prior to a P trap, not downstream of a P trap.