It is a used to detect gross leaks in sealed flexible packages. The principle is simple yet effective: a sealed package is submerged in a liquid (usually water or a surfactant solution), and a vacuum is applied. If the package leaks, bubbles will escape from the defect point.
Apply vacuum gradually to a predefined level (e.g., 25 inHg for most flexible packages) while observing the package. astm d3078 pdf 2021
Hold the vacuum for the specified dwell time (typically 30–60 seconds, but can be longer per internal protocols). It is a used to detect gross leaks