There are several standardized test methods available for measuring fabric air permeability. The most commonly used test methods are:

1. ASTM D737 – Standard Test Method for Air Permeability of Textile Fabrics: This test method covers the measurement of the air permeability of textile fabrics. The test is performed using a constant airflow rate, and the results are reported in cubic feet per minute per square foot of fabric (CFM/ft2).

2. ISO 9237 – Textiles – Determination of the Permeability of Fabrics to Air: This test method is similar to ASTM D737, but it uses a different test apparatus and specifies a different unit of measurement. The test is performed using a constant pressure drop, and the results are reported in liters per second per square meter of fabric (L/s/m2).

3. BS EN ISO 9237 – Textiles – Determination of the Permeability of Fabrics to Air: This test method is the European version of ISO 9237 and is used in Europe and other parts of the world. The test is performed using a constant pressure drop, and the results are reported in liters per second per square meter of fabric (L/s/m2).

4. ASTM D737M – Standard Test Method for Air Permeability of Textile Fabrics (Metric): This is the metric version of ASTM D737 and is used in countries that use the metric system. The test is performed using a constant airflow rate, and the results are reported in liters per second per square meter of fabric (L/s/m2).

When selecting a test method for fabric air permeability, it is important to consider the requirements of the application and the regulations that apply to the product. It is also important to ensure that the test method is recognized by the relevant industry standards organizations. The ASTM and ISO test methods listed above are widely recognized and accepted in the textile industry, and they are frequently used for product development, quality control, and regulatory compliance testing.