This document specifies the field of application, the dimensional, the physico-chemical, the design, the hydraulic, the mechanical, and the acoustic characteristics of in-line anti vacuum valve family D Type A. This document covers in-line anti vacuum valve family D Type A, intended to prevent pollution of potable water by backflow, caused by backsiphoning only. It is applicable to in-line anti vacuum valve in denominations DN 10 up to DN 50. It covers in-line anti vacuum valve of PN 10 that are capable of working without modification or adjustment: - at any pressure, up to 1 MPa (10 bar); - with any pressure variation, up to 1 MPa (10 bar); - in permanent duty at a limited temperature of 65 °C and for maximum 1 h at 90 °C. It specifies also the test methods and requirements for verifying their characteristics, the marking and the presentation at delivery.