Externally and internally mounted air transfer devices. standard by British-Adopted European Standard,/11/ View all product details Supersedes BS EN ISBNSubjects. National foreword This British Standard is the UK BS ENTC Tracked Changes. Performance testing of components/products for residential ventilationVentilation;Flow rates;Flow measurement;Ventilation BS ENVentilation for buildings. Performance testing of components/products for residential ventilationExternally and internally mounted air