How to test the air permeability of packaging bags? In order to prevent the air permeability of the packaging bag from affecting the product, it is very necessary to test the air permeability of the packaging bag to ensure the gas barrier properties of the packaging material. From the perspective of the principle of testing the air permeability of packaging bags, the test methods for air permeability of packaging bags can be divided into two types: differential pressure test and power analysis sensor test. 1. Test principle of pressure difference method: the test chamber is divided into two independent spaces by the film to be tested, and one side (high pressure chamber) is filled with test gas, and a certain pressure difference is formed on both sides of the sample, and in the gas A certain pressure difference is formed. The high-pressure chamber leaks into the low-pressure chamber through a membrane. The permeability of the gas can be obtained by measuring the pressure or volume change of the low pressure chamber. 2. The test principle of the coulometric sensor method: the test chamber is divided into two independent gas flow systems by using the film to be tested, and one side is the flow gas to be tested (pure oxygen or a mixed gas containing oxygen can be used to set the relative humidity) and the other side is flow. nitrogen. The pressure difference across the sample is equal, but the oxygen partial pressure is different. Under the action of the concentration difference, the oxygen passing through the film is sent to the electroanalytical sensor under nitrogen flow to calculate the oxygen transmission rate of the material. The test principles of differential pressure method and equal pressure method are different. The units of the test results are different under different test conditions (the unit of the differential pressure method is cm3/m2? 24h? 0.1MPa, and the unit of the equal pressure method is cm3/m2·d). Corrected raw data are theoretically not comparable. However, by calibrating the isostatic apparatus with a standard membrane and performing a formal test using a correction factor, it is possible to compare the test results of the differential pressure method and the isostatic method. Due to the support of the theory of membrane technology, the differential pressure method has been used as the basic method of air permeability testing, and has been adopted by scientific research and testing institutions. Its outstanding advantage is that it is not selective to the test gas and is very versatile for different test gases. With the advancement of vacuum gauge detection technology and the application of vacuum technology in equipment design, the detection accuracy of equipment and the repeatability of test data have been greatly improved. Sensor methods have emerged as oxygen detector technology has matured. Since the sensors used are consumable parts, the calibration factors obtained through equipment calibration are not long-term valid, and periodic equipment calibration is required as needed. When the sensor reaches a certain level, the sensor must be replaced. What is described above is “How to test the air permeability of plastic packaging bags of “Shenzhen packaging bag manufacturers”?” ” in its entirety.
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