I feel like that's what I'm asking when I ask what authority requires our 1" air gap. I need to justify drainage requirements to non-dialysis type people. While I wait for freshly printed AAMI regs, can anyone help me with a code to reference?

I'm actually thinking it's local plumbing codes that require them. I'm in Cook County, IL.

Try this site:

http://www.portlandonline.com/WATER/index.cfm?a=28137&c=29782

Cook County has some of the strangest requirements. Typically, they do not allow backflow preventers; you have to use glass pipe on the drain lines, etc.

AAMI does not specify a 1" gap. AAMI says to follow the local plumbing code. I have a 1999 letter from the Illinois Department of Public Health on "Plumbing within Dialysis Centers." For the drain, it says "Each dialysis unit shall be indirectly connected to the stand pipe (gray box) with a fixed air gap." If you need a copy, email me. RenalWeb wont let me tell you what my email address is so you will have to go to my website (RenalWeb wont let me tell you what that is either, but it has something to do with Florian Services, a dot, and com).

As is stated in the link provided by Mark, "An acceptable air gap must be twice the supply pipe diameter, but never less than one inch."