Type EB – Non-verifiable single check valve:  

means a non-verifiable mechanical backflow prevention device which will permit water to flow from upstream to downstream but not in the reverse direction. 

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

Backflow by back pressure: fluid category 2

Backflow by back siphonage: fluid category 2

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