Pressure Decay

Pressure Decay Leak Testing is a deterministic method used to evaluate leaks and package integrity by monitoring changes in pressure over a defined test period. It is widely used for container closure integrity testing (CCIT), pharmaceutical packaging evaluation and quality control applications.

During a pressure decay test, the test package or test system is pressurized with air or another suitable gas. After the pressure stabilizes, the system is isolated from the pressure source. Precision sensors then monitor the pressure over time.

If gas escapes through a defect, the internal pressure decreases. The measured pressure loss can be compared with validated acceptance limits to determine whether the package passes or fails the leak test.

Pressure decay testing provides quantitative and objective results without requiring dyes or microbial challenge organisms, making it suitable for many pharmaceutical and medical packaging applications.

 

Pressure Decay Leak Test Principle

 

Pressure decay leak detection is a deterministic, non-destructive container closure integrity testing method that evaluates package integrity by monitoring changes in internal pressure over time. The package is pressurised with compressed air or gas, then isolated and the pressure loss is measured by calibrated sensors over a set period. If gas escapes through a defect, internal pressure decreases at a rate proportional to leak size; a measurable drop in pressure indicates the presence of a leak. The method is commonly applied to rigid and semi-rigid pharmaceutical packaging, including bottles, cartridges and certain device housings.

 

Pressure Decay Testing for CCIT

 

Container Closure Integrity Testing is used to evaluate whether a package can maintain the barrier necessary to protect a pharmaceutical product throughout its intended shelf life.

Pressure decay can be used as part of a deterministic CCIT strategy when the package configuration allows controlled positive-pressure testing.

Compared with probabilistic methods such as dye ingress or microbial ingress testing, pressure decay provides instrument-based measurements that can be quantitatively evaluated.

For pharmaceutical packaging, the method may be used during:

● Package development
● Container closure system evaluation
● Process validation
● Production quality control
● Packaging defect investigation
● Transportation studies
● Stability programs

Method parameters should be developed specifically for the package being tested, particularly when evaluating small leaks.

 

What Packages Can Be Tested?

 

Pressure decay leak testing can be applied to different package configurations when an appropriate test fixture and test method are available.

Common applications include:

● Bottles
● Cartridges
● Device housings
● Pouches
● Flexible packages
● Foil-sealed trays
● Semi-rigid packaging
● Selected pharmaceutical container systems

For flexible packaging, package deformation can significantly affect pressure measurements. Appropriate restraint plates or fixtures may therefore be required to control package expansion during the test.

ASTM F2095 specifically addresses pressure decay leak testing for flexible packages with and without restraining plates, including nonporous film, foil and laminate flexible packages.

 

Pressure Decay Testing for Flexible Packages

 

Flexible packages require particular attention because introducing positive pressure can cause the package walls to expand.

Package expansion can create pressure changes that are unrelated to actual leakage and reduce measurement repeatability.

Depending on the package design, a pressure decay test may therefore use restraining plates or a specially designed fixture to limit deformation.

Important parameters include:

● Package volume
● Test pressure
● Stabilization time
● Measurement time
● Package flexibility
● Fixture design
● Temperature
● Expected leak size

These parameters should be established during method development rather than applying the same test conditions to every package.

 

Test Equipment in Our Lab

 

Zholion MC-DUO Packaging Leak Detector

 

 

Regulatory Requirements

USP<1207>

 

Pressure decay is listed as a deterministic leak test method.

USP <1207> states a preference for deterministic tests on the basis that they are non-invasive, produce repeatable and predictable results, and are suited to 100% testing.

Method validation is required to demonstrate detection capability at the product-specific Maximum Allowable Leakage Limit (MALL)

 

USP 382

 

Points directly to USP <1207> for container closure integrity testing methodologies.

System-level integrity assessment using deterministic CCIT methods – including pressure decay – is required by 1 December 2025.

 

ASTM F2095

 

The test method cover the measurement of leaks in nonporous film, foil, or laminate flexible pouches and foil-sealed trays.

These test methods will detect leaks at a rate of 1 × 10⁻⁴ sccs (standard cubic centimetres per second) or greater, in flexible packages.

The pressure decay method of leak testing is a physical measure of package integrity.

When testing medical packaging which must conform to ISO 11607-1:2006 standards, it may be necessary to verify the results of the pressure decay test method with other sterile package integrity test methods.

Test Method A covers pressure decay leak test for flexible packages without restraining plates; Test Method B covers pressure decay leak test for flexible packages with restraining plates.

 

EU GMP Annex 1

 

Container closure integrity validation is mandatory for all sterile products.

Deterministic methods such as vacuum decay and pressure decay are recognised as compliant with Annex 1 integrity requirements

 

Chemical Injectable Packaging System Integrity Study Technical Guideline (China)

 

This guideline covers the entire lifecycle of CCIT for chemical injectables, referencing both domestic and international technical guidance and standards. It addresses method selection, validation, stability testing requirements, and commercial production inspection.

 

Deterministic leak test methods (including pressure decay and vacuum decay) are cited as acceptable for CCIT validation.

The guideline states that deterministic methods capable of detecting the product-specific Maximum Allowable Leakage Limit (MALL) are preferred. If the sensitivity of a deterministic method cannot reach the MALL level, or the MALL is not clearly defined, at least two methods (one of which should be a microbial challenge) are recommended.

 

 

Advantages of Pressure Decay Leak Testing

 

Pressure Decay Leak Testing offers several advantages for package integrity evaluation:

● Non-destructive testing capability for suitable package configurations
● Quantitative pressure measurement
● Objective pass/fail criteria
● No dye solution required
● No microbial challenge required
● Relatively straightforward test principle
● Suitable for automated test systems
● Applicable to different rigid, semi-rigid and flexible package configurations

Because results are instrument-based, the method can provide better repeatability and objectivity than visual or operator-dependent leak tests when properly developed and validated.

 

Factors Affecting Pressure Decay Test Results

 

Pressure decay testing is sensitive to several physical and environmental factors.

Package Volume

Larger internal volumes may produce different pressure responses from smaller packages for the same leak size.

Temperature

Gas pressure changes with temperature. Temperature differences between the package, test gas and environment can therefore influence pressure decay measurements.

Stabilization Time

Insufficient stabilization may produce apparent pressure changes that are not caused by leakage.

Package Deformation

Flexible or semi-rigid packaging can expand under positive pressure, making proper fixtures and stabilization particularly important.

Test Pressure

The selected test pressure should provide sufficient sensitivity without damaging or permanently deforming the package.

For reliable package leak testing, these variables should be controlled and documented during method development and validation.

 

Pressure Decay vs. Vacuum Decay

 

Both pressure decay and vacuum decay are deterministic leak detection methods, but their testing principles are different.

Pressure decay testing creates positive pressure inside the test system and monitors pressure loss.

Vacuum decay testing applies vacuum around the package and monitors changes in chamber pressure.

Pressure decay can be particularly useful for packages that can be internally pressurized or for certain flexible packaging configurations. Vacuum decay is widely used for sealed pharmaceutical containers where the package can be tested inside a vacuum chamber without direct internal pressurization.

The appropriate method should be selected according to package geometry, materials, contents, expected defect size and required detection capability.

 

Zholion-Pressure Decay Leak Testing Supplier

 

Zholion provides Pressure Decay Leak Testing and CCIT technical support for pharmaceutical and medical packaging.

Our team can assist with package evaluation, method feasibility studies, test parameter development and container closure integrity testing according to specific package characteristics and quality requirements.

Provide your package type, dimensions, materials, closure configuration and required leak detection level so that an appropriate pressure decay testing method can be evaluated.

 

Need Help with Pressure Decay Leak Testing?

 

Not sure whether pressure decay is suitable for your packaging?

Send Zholion your package type, dimensions, materials and testing requirements. Our technical team can help evaluate the appropriate CCIT method and pressure decay test conditions for your application.

Contact Zholion for Pressure Decay Leak Testing and CCIT Support.