Calcium Test - Different test methods for WVTR on barriers, with an emphasis on ultra barriers, sources of error/irreproducibility, limits, etc – basically why it is hard to do it right.

Calcium Test - Different test methods for WVTR on barriers, with an emphasis on ultra barriers, sources of error/irreproducibility, limits, etc – basically why it is hard to do it right.

Matt Reese 
NREL

Measuring the water vapor rate transmission (WVTR) of barrier materials at low levels (<10-4 g/m2/day) is challenging. This talk will describe how WVTR values should be understood and some of the existing methods used for characterizing materials. In particular, we will discuss the National Renewable Energy Laboratory’s electrical calcium test method for measuring WVTR. We will examine some of the challenges in making high quality, repeatable measurements. As no WVTR standards exist below ~ 10-2 g/m2/day, as time permits, we will present some of our work in developing standards for WVTR levels between 1 and 10-6 g/m2/day.