This document specifies: a) field of application; b) requirements for in line anti-vacuum valves; c) dimensional, the physico-chemical properties and the properties of general hydraulic, mechanical and acoustic design of in-line anti-vacuum valves DN 10 to DN 50; d) test method and requirements for verifying these properties; e) marking and presentation; f) acoustics. This document specifies the characteristics of in-line anti-vacuum valves DN 10 to DN 50 that are suitable for use in drinking water systems at pressures up to 1 MPa (10 bar) and temperatures up to 65 °C and for 1 h at 90 °C.