Type HA – Hose union backflow preventer

A mechanical backflow prevention device for fitting to the outlet of a hose union tap and consisting of a single check valve with air inlets that open if the flow of water ceases. 

Maximum permissible fluid category against which a Type HA device is accepted as adequate backflow protection:

Backflow by back pressure: fluid category 2

Backflow by back siphonage: fluid category 3

Interpretation given in Regulators’ Backflow Specification - backflow prevention arrangements and devices: backflow prevention arrangements