This document specifies, the dimensional, the physical-chemical, the design, the hydraulic, the mechanical and the acoustic characteristics of mechanical disconnectors flow actuated Family G, type B. This document is applicable to mechanical disconnectors flow actuated in nominal sizes DN 8 up to DN 250, intended to prevent the return of water having lost its original sanitary and drinking qualities (called polluted water in this document), into the potable water distribution system whenever the pressure of the latter is temporarily lower than in the polluted circuit. This document covers the mechanical disconnector of PN 10 that are capable of working without modification or adjustment: at any pressure up to 1,0 MPa (10 bar); in permanent duty at a limit temperature of 65 °C and 90 °C for 1 h maximum. It specifies also the test methods and requirements for verifying these characteristics, the marking and the presentation at delivery.