TL;DR
An air gap fitting is the small chrome or plastic cylinder mounted at the sink rim that routes dishwasher drain water through an open vertical break before it continues to the disposal or drain, making backflow of dirty water into the dishwasher physically impossible. The unobstructed opening, not a valve, is what provides the protection.
What it means
An air gap fitting is the small chrome or plastic cylinder mounted at the sink rim that routes dishwasher drain water through an open vertical break before it continues to the disposal or drain, making backflow of dirty water into the dishwasher physically impossible. The unobstructed opening, not a valve, is what provides the protection. Some plumbing codes, notably in California and Washington, require it on every dishwasher installation, while others accept a high loop of the drain hose instead. Water spitting from its cap signals a clogged downstream hose, not a failed part.
Where it sits in the glossary
Air gap fitting is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
License: CC-BY-4.0 — quote freely with attribution to ProFix Editorial Team / ProFix Directory.