The structure of the test instrument used in the microporous paper air permeability test method is roughly the same as that of the Gurley air permeability meter, which is mainly composed of an outer cylinder, an inner cylinder, a measuring head, and a pressurizing mechanism. However, the specifications are different. The height of the outer cylinder is 254.5-355.6mm, the inner diameter is 44mm, the height of the inner cylinder is 238mm, the inner diameter is 25mm, and the outer diameter is 25.4mm. The test area is 6.4cm2, and the weight is (167±0.1)g. 310.6mm water column height. The tightness requirement is that the leakage of air within 5 hours does not exceed 5mL. The specific test steps are as follows.
①Sample collection and processing. Sampling according to GB450, cut 10 pieces of 51mm×51mm samples along the transverse direction of the paper web, and mark the front and back sides. According to the requirements of GB10739, carry out temperature and humidity pretreatment on the samples.
②Adjust the instrument level.
③ Put mercury with a height of about 127mm into the outer cylinder. Other test steps are the same as those of the Gurley air permeability Tester.
④ Lift the bracket and raise the inner cylinder.
⑤ Place the sample between the upper and lower clamp rings, lower the inner cylinder, make it float in the oil, and slide down freely by its own weight. When the zero scale line of the inner cylinder is aligned with the top of the outer cylinder, start the stopwatch for timing. When the inner cylinder drops to the 100mL scale line, stop timing and read the time recorded by the stopwatch, accurate to 0.2s.
⑥ Put down the lower chuck, lift the inner cylinder at the same time, and support it with a bracket, take out the sample, and prepare for the next test.
The test results are expressed as the arithmetic mean of all test results (including positive and negative sides), and can also be converted into international units to report the results.
