Standard Test Method for - Air Permeability of Textile Fabrics

ASTM D737 is a standard test method for measuring the air permeability of textile fabrics. This test is applicable to various types of fabrics, including yarns, greige fabrics, knitted fabrics, etc., and it measures a fabric's air permeability. The test methods can be used to determine the characteristics of fabrics, such as air tightness, frictional effects, and to measure a fabric's air permeability and thickness under compression. This standard provides an important quality control method for the textile industry and can be helpful to end-users.

Test Method:

The test uses a circular test area, and fine powder is sprayed onto the test area using an aerosol spray applicator. Airflow passes through the test area from a flow meter sensor and related equipment on one side and creates a differential pressure on a capture device on the other side. The test process measures this differential pressure with an instrument and calculates the air permeability of the test sample.  The difference in airflow velocity on both sides of the test helps to determine the total flow rate during the test. In addition, the test can also monitor the permeability using full temperature differential colorimetry or other methods.

Test Equipment:

To measure the air permeability of the fabric, the test process uses flow meter sensors, differential pressure instruments, a circular test area, and an aerosol spray applicator to prepare the standardised test sample. The airflow meter sensor is used to measure the size and direction of the airflow velocity. The differential pressure instrument is used to monitor the airflow differential pressure during the test. The circular test area provides a standardised size and area for the test and reduces the risks of testing for non-test personnel. The aerosol spray applicator is used to prepare the testing sample in standardised manner.

Precautions:

During the test, the temperature and relative humidity should be maintained relatively constant, and tests should be avoided in untested or uncontrolled environments. Check that the size of the sample used meets the requirements and that the placement of the sample board does not suffer from compression due to bending or folding. Any pressure or rotation of the tested material can affect test results. Fabrics of different thicknesses and different textures should be decompressed and compensated according to the air infusion rate required during testing.

Conclusion:

ASTM D737 includes a series of procedures that standardise the air permeability of fabrics. These tests provide a support system for controlling the quality of textile products and can help manufacturers evaluate the quality of their products and enjoy the benefits on the final product. Standardised test methods can ensure that fabric air permeability characteristics conform to best practices.