Test Method for Air Permeability of Textile Fabrics

ASTM D737 is a test method used to measure the air permeability of textile fabrics. This test provides a quantitative measurement of the ease with which air passes through a fabric under specified conditions. The air permeability of a fabric is an important property that can affect its performance in various applications. ASTM D737 provides a standardized procedure for conducting the test and obtaining consistent and comparable results.

Here is a detailed explanation of the ASTM D737 test method for air permeability of textile fabrics:

1. Test Apparatus:

   - Air permeability testing instrument: This instrument consists of a test head, clamping ring, specimen holder, and a vacuum source. The test head has a circular opening throughwhich the air flows. It is connected to the vacuum source to create a pressure difference across the fabric specimen.

   - Stopwatch or timer: Used to measure the test duration.

2. Specimen Preparation:

   - Cut representative specimens from the fabric sample. The specimens should be large enough to cover the test head opening completely.

   - Condition the specimens in a standard atmosphere (temperature and humidity) for a specified period before testing to ensure moisture equilibrium.

3. Test Procedure:

   - Place the fabric specimen over the test head opening and secure it with the clamping ring to create an airtight seal.

   - Connect the vacuum source to the test head and start the vacuum to create a pressure difference across the fabric specimen.

   - Measure the test duration using a stopwatch or timer.

   - Record the pressure difference and the corresponding air flow rate.

4. Calculation:

   - Calculate the air permeability of the fabric using the following formula:

     Air Permeability (cm3/cm2/s) = (Q × t) / (A × ΔP)

     Where:

     Q = Air flow rate (cm3/s)

     t = Test duration (s)

     A = Test area (cm2)

     ΔP = Pressure difference (Pa)

5. Reporting:

   - Report the air permeability value along with the test conditions, including the pressure difference applied, test duration, and any relevant information about the fabric sample.

   - It is recommended to conduct multiple tests and report the average value to account for any variations.

It's important to note that the units of air permeability can vary depending on the specific requirements of the application. Common units include cm3/cm2/s and ft3/min/ft2.

ASTM D737 provides a standardized method for evaluating the air permeability of textile fabrics. The test results can be used to compare the air permeability of different fabrics, assess their suitability for specific applications such as clothing, filtration, and air barrier systems, and ensure compliance with industry standards and regulations.