title: Accurate measurements of water vapor transmission through high-performance barrier layers.
abstract: We report a new approach to measuring very low rates of water vapor transmission through high-performance barrier layers, based on detection of the water vapor by cavity ring-down infrared spectroscopy. It provides accurate and traceable measurements with a detection limit for water vapor transmission significantly below 1 × 10(-4) g/m(2)/day. The system is underpinned by dynamic reference standards of water vapor generated between 5 and 2000 nmol∕mol with an estimated relative expanded uncertainty of ±2%. It has been compared with other methods and demonstrates good comparability.
authors.affiliation: National Physical Laboratory, Analytical Science Division, Hampton Road, Teddington, Middlesex, TW11 0LW, United Kingdom. paul.brewer@npl.co.uk
authors.forename: P J
authors.initials: PJ
authors.lastname: Brewer
authors.forename: B A
authors.initials: BA
authors.lastname: Goody
authors.forename: Y
authors.initials: Y
authors.lastname: Kumar
authors.forename: M J T
authors.initials: MJ
authors.lastname: Milton