The ASTM standard for air permeability testing of fabrics is ASTM D737 - Standard Test Method for Air Permeability of Textile Fabrics. This standard provides a method for determining the air permeability of woven, knitted, or nonwoven textile fabrics.
ASTM D737 outlines the procedure for measuring the air permeability of fabrics using an instrument called a "porosity tester" or "air permeability tester." The test involves measuring the rate of airflow through a specified area of fabric under controlled conditions.
The standard covers various aspects of the testing process, including the preparation of fabric samples, conditioning requirements, test apparatus specifications, test parameters such as pressure differentials and test area sizes, and calculations for determining air permeability values.
It is important to note that ASTM D737 is just one of the ASTM standards related to air permeability testing. There are other standards that may be applicable depending on the specific type of fabric or material being tested. Therefore, it is advisable to refer to the appropriate ASTM standard that best suits your testing requirements.