What Is a Leak Rate
A leak rate is a quantitative measure of how much gas or liquid passes through a defect in a sealed package over a defined period of time. In container closure integrity testing (CCIT), a leak rate is used to objectively determine whether a package can maintain sterility and product protection throughout its shelf life.
Rather than simply stating whether a package “leaks” or “does not leak,” leak rate defines how much leakage occurs, expressed in measurable units such as mbar·L/s or standard cubic centimeters per second (sccs). This makes leak rate a critical parameter for scientific, repeatable, and defendable integrity testing.
Why leak rate matters in CCIT
Not all leaks pose the same risk. A large, obvious defect may cause immediate failure, while a microscopic leak may compromise sterility slowly over time. Leak rate allows manufacturers to differentiate between harmless defects and those that represent a real contamination risk.
Regulatory guidance, including USP <1207>, emphasizes the importance of linking leak detection capability to product risk. This is achieved by defining a maximum allowable leakage limit (MALL), the largest leak rate a package can have without risking sterility loss during its intended shelf life.
How leak rate is determined
Deterministic CCIT methods measure leak rate using physical principles such as:
- Pressure change in a sealed test chamber
- Electrical conductivity changes in liquid-filled containers
- Tracer gas flow through a defect
These measurements provide repeatable, quantitative data that can be validated and statistically analyzed. In contrast, probabilistic methods typically do not define or measure leak rate, making them difficult to justify during audits.
Leak rate vs sensitivity
High sensitivity alone does not define good CCIT performance. A method must reliably detect leaks at or below the defined MALL with repeatability and confidence. Measuring leak rate enables manufacturers to balance sensitivity with real-world relevance, avoiding unnecessary rejects or false confidence.
Conclusion
Leak rate transforms package integrity testing from a subjective check into a science-based decision tool. By defining, measuring, and validating leak rates, deterministic CCIT supports defensible sterility assurance strategies, an approach central to the methodologies used by PTI Packaging Technologies & Inspection.