ASTM D3078 is a standard test method developed to detect gross leaks in flexible packaging containing a headspace gas through bubble emission. This test provides a relatively simple and effective means of identifying significant leaks within a package.
The test procedure involves the use of a vacuum chamber made of a transparent material capable of withstanding a pressure differential of about one atmosphere. The chamber is equipped with a vacuum-tight cover, a pressure gauge, an inlet tube from a vacuum source, and an outlet tube to the atmosphere.
To conduct the test, the flexible packaging is submerged in a test fluid that will not degrade its material. Both the test fluid and the sample should be at equilibrium with normal room temperature. Vacuum is then applied to the chamber, creating a pressure difference between the inside and outside of the packaging. If a leak is present, the escaping gas will form bubbles in the test fluid, indicating a failure in the integrity of the packaging.
This test method is sensitive to leaks on the order of 1 × 10−5 atm cm3/s (1 x 10−6 Pa m3/s). However, it is important to note that smaller leaks might not be detected due to viscoelastic effects or trapped air in the product that can block small openings. This is particularly concerning when positive pressure inside the pouch, created after the vacuum is drawn, forces the product to plug small leaks.
It is also important to note that the detectable leak size depends on the nature of the contained products, the packaging material, and the specific test parameters selected. Thus, ASTM D3078 provides guidelines for evaluating the integrity of flexible packaging, but it may not detect all potential failures.