2. Place the prepared sample on the movable chuck of the instrument and clamp the sample.
3. Turn on the power of the instrument, turn on the power switch, press "start of test" and the instrument starts to work, and adjust the test gas flow to 8L/min. The diameter of the sample test area is 25mm, and the test area is 4.9cm2. Record the pressure difference displayed on the meter, in Pa.
4. After the test is completed, press "Test Stop" to stop the instrument. Pull back the chuck and take out the sample.
5. Repeat steps 2.3 and 4. Average the pressure difference values measured by the 5 samples, and the obtained value PM is the average value of the pressure difference of the test sample, the unit is Pa. According to the formula ΔP=PM/4.9, the gas exchange pressure difference on both sides of the sample is calculated. The result is reported as the pressure difference per square centimeter. ΔP should not be greater than 49Pa.