ASTM D6701-21 - Standard Test Method for Determining Water Vapor Transmission Rates Through Nonwoven and Plastic Barriers

1.1 This test method covers a procedure for determining the rate of water vapor transmission ranging between 500 to 100 000 g/(m²·day) through nonwoven and plastic barrier materials. The method is applicable to films, barriers consisting of single or multilayer synthetic or natural polymers, nonwoven fabric, and nonwoven fabrics coated with films up to 3 mm (0.1 in.) in thickness.

1.2 This test method provides for the determination of (1) water vapor transmission rate (WVTR), and (2) the permeance to water vapor.

1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. The acceptable units for WVTR are usually g/(m²·day).

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.