This standard specifies two main test methods for evaluating the sealing performance of flexible packaging. The first is the vacuum chamber method, which involves creating a pressure difference between the inside and outside of a submerged package by evacuating air, and then observing for continuous bubbles or water ingress to determine leaks. This method is suitable for packaging with outer materials that are not significantly affected by water, such as plastic films. The second method is the liquid filling method, where test liquid is injected into the package, and leakage is assessed either by the principle of vacuum expansion or by placing the package on filter paper to observe liquid seepage. This method is primarily used for packaging whose performance would be significantly compromised by water, such as those with paper outer layers. Conducting these tests requires specialized sealing testers, also known as leak detectors. The core component of such equipment is a vacuum chamber equipped with a vacuum system and an illumination-observation system, ensuring clear visibility of leaks at the micrometer level.