Type AA air gap – air gap with unrestricted discharge
A non-mechanical backflow prevention arrangement of water fittings where water is discharged through an air gap into a receptacle which has at all times an unrestricted spillover to atmosphere.
Maximum permissible fluid category against which a Type AA air gap is accepted as adequate backflow protection:
Backflow by back pressure: fluid category 5
Backflow by back siphonage: fluid category 5
Interpretation given in Regulators’ Backflow Specification - backflow prevention arrangements and devices: backflow prevention arrangements