Vacuum decay is a test method used to test package integrity. A sample is placed under controlled vacuum condition. The difference in pressure from the internal atmosphere of the package and the external will force the internal gas to move toward the external area of the packaging. The flow occurring will produce an increase in pressure. This increase will be measured and quantified during the test time.
The increase in pressure based on empirical test will be different in case of a leaking package or a leaktight package and the software will automatically detect the higher increase of a leaking package showing a FAIL result.
This technique is nominated as deterministic in USP <1207>, usually accepted as an FDA consensus method for packaging testing and described in ASTM F2338.