Why Do Good Packages Fail Leak Testing?

Packages that appear to be acceptable can fail leak testing because of genuine microscopic defects, fixture leakage, inconsistent sample positioning, temperature effects, or test parameters that are not suitable for the package. A failed result should therefore be investigated rather than automatically classified as either a defective package or a false rejection. Zholion’s leak detection equipment supports different pharmaceutical and medical-device packaging formats, and selecting the right test method is essential for distinguishing package defects from measurement problems.

In pharmaceutical manufacturing, an unexpected failure can interrupt production, increase inspection costs, and delay batch decisions. However, accepting a failed package without a documented investigation may create a product-quality risk. The objective is to establish whether the package has a real integrity defect, whether the test was valid, and what evidence supports the final decision.

 

1. A Package Can Look Good and Still Leak

Visual inspection is useful for identifying obvious cracks, chips, damaged closures, and deformation. It cannot reliably detect every small leak path.

Potential defects include a microscopic crack in a container, an incomplete seal, a damaged stopper interface, a channel in a flexible package seal, or an assembly defect that is not visible externally.

A package may also have a defect that becomes detectable only under the pressure, vacuum, or other conditions used by the selected test method.

For this reason, appearance and integrity should be evaluated as separate quality attributes. A visually acceptable package that fails a valid, suitable CCIT method requires investigation even if no obvious damage can be found.

 

2. Fixture Leakage Can Create False Rejections

One of the first causes to investigate is leakage at the interface between the test fixture and the package. The instrument may detect a pressure change correctly, but that change may originate from the test setup rather than the package closure.

Common contributing factors include:

• Worn or damaged gaskets.

• Dirt, product residue, or particles on sealing surfaces.

• Incorrect package positioning.

• Inconsistent clamping force.

• Fixture dimensions that do not match the package.

• Damage or wear caused by repeated use.

To investigate, inspect the fixture and perform the approved system checks. Where appropriate, compare results using a verified reference configuration. Do not modify the fixture or bypass its sealing system simply to obtain a passing result.

Zholion offers custom CCIT chambers and fixtures for different packaging formats. Correct fixture geometry and repeatable positioning are important parts of a reliable test method.

 

3. Temperature and Stabilization Can Affect Results

Temperature changes can affect pressure readings, gas behavior, package dimensions, and the response of certain packaging materials.

A package tested immediately after transport may be at a different temperature from one that has equilibrated in the laboratory. Likewise, insufficient stabilization time can make readings less consistent when the method depends on a stable pressure or vacuum condition.

Review ambient temperature, sample-conditioning time, and the stabilization period defined by the test procedure. Repeatability comparisons should use consistent conditions wherever practical.

Temperature effects should not be used as a convenient explanation for every unexpected failure. The investigation should determine whether the observed conditions plausibly explain the result and whether the test remains valid.

 

4. The Test Method May Not Match the Package

Different package designs and defect types may require different testing technologies. A method that is suitable for one container format may not provide adequate sensitivity or a reliable measurement for another.

Examples of technologies used in CCIT include:

• Vacuum decay: Monitors pressure-related changes under controlled vacuum conditions.

• Pressure decay: Measures pressure changes after a test system or package has been pressurized and isolated.

• High-voltage leak detection (HVLD): Uses electrical properties to detect certain defects in compatible packages.

• Helium leak detection: Uses helium as a tracer gas for applications requiring a suitable high-sensitivity method.

• Laser-based headspace analysis: Evaluates selected headspace gas parameters in compatible packages.

Method selection depends on package materials, product properties, expected leak size, test conditions, and whether the test must be non-destructive.

For example, Zholion’s pressure decay testing technology may be relevant to compatible packages that can be evaluated through controlled pressure measurement. The appropriate method and its detection capability should be established during method development and validation.

 

5. Acceptance Criteria May Be Unsuitable

A package may be rejected frequently when the acceptance threshold is not appropriately established for the intended application, package configuration, and test method.

The solution is not to widen the acceptance limits until more packages pass. Instead, determine whether the method can reliably distinguish acceptable packages from packages that present an unacceptable integrity risk.

Acceptance criteria should be supported by a documented rationale and validated performance. Where a result falls close to the decision threshold, the procedure should define how borderline outcomes are assessed.

Changes to thresholds or test parameters require appropriate review and authorization. They should not be made informally during routine production.

 

6. Sample Handling Can Create or Expose Defects

Packages can be damaged during sampling, transport, cleaning, loading, or removal from the fixture. A glass container may develop a crack after impact, while a flexible package may experience stress or deformation around a seal.

Handling can also introduce contamination to the fixture or closure area. In some cases, the package may have been compromised before it reaches the test station.

Review how the sample was collected, identified, transported, stored, and prepared. If a handling-related cause is suspected, compare the sample history with the approved procedure and investigate whether other samples were exposed to the same conditions.

Do not discard a failed sample before preserving the evidence required for the investigation.

 

7. How to Determine Whether a Failure Is Genuine

A practical investigation can follow this sequence:

Step 1: Preserve the result. Record the original failure, raw readings, instrument alarms, and test conditions.

Step 2: Inspect the sample. Look for visible damage, closure displacement, or signs of handling problems.

Step 3: Check the test system. Review fixture condition, instrument status, calibration, and reference checks.

Step 4: Verify the method. Confirm that the correct recipe, test parameters, and acceptance criteria were applied.

Step 5: Review controls. Use the approved positive and negative controls, where applicable, to confirm that the system is responding as expected.

Step 6: Conduct justified follow-up testing. Use an approved investigation plan and an appropriate complementary method if necessary.

Step 7: Document the conclusion. Explain whether the failure is attributed to the package, test setup, method, or another supported cause.

A passing result from an alternative method does not automatically invalidate the original failure. Each method has its own operating principle and detection limitations, which must be considered in the final assessment.

 

8. How Can Manufacturers Reduce False Rejections?

Reducing false rejections requires control of the complete testing process.

• Inspect and maintain fixtures regularly.

• Use a standardized sample-conditioning procedure.

• Control recipe versions and access to critical parameters.

• Confirm instrument status before routine testing.

• Train operators in package positioning and handling.

• Monitor failure rates and borderline results over time.

• Establish a documented procedure for investigating unexpected failures.

When false rejections recur, review the fixture, instrument, method, and manufacturing process together. Repeatedly retesting individual packages without addressing the underlying issue can consume time without improving confidence in the results.

 

Frequently Asked Questions

Can a good-looking vial still fail CCIT?

Yes. Some integrity defects are too small to be detected visually. A failed result from a suitable, validated method must be investigated even if the package appears undamaged.

What is the difference between a genuine leak and a false rejection?

A genuine leak is an integrity defect in the package, while a false rejection is an incorrect failure classification. Fixture leakage, unsuitable parameters, or unstable test conditions can contribute to false rejections, but the distinction requires documented evidence.

Can changing the test threshold reduce false rejections?

Changing a threshold without scientific justification can increase the risk of accepting defective packages. First investigate the root cause and confirm that the acceptance criteria are appropriate for the intended application.

Which CCIT method should be used for pharmaceutical packaging?

The appropriate method depends on the package, product, expected defect, required sensitivity, and validation requirements. Method selection should be based on documented suitability rather than choosing the technology that produces the highest pass rate.

How can fixture problems be detected?

Inspect seals and contact surfaces, verify package positioning, review maintenance records, and perform approved reference checks. A recurring failure pattern across otherwise unrelated samples may justify examining the fixture and test setup.

 

Improve Leak-Test Confidence with Zholion

Reliable leak testing depends on matching the method to the package and controlling the fixture, environment, parameters, and sample-handling process. Contact Zholion at marketing@zholion.co or visit www.zholionccit.com to discuss leak detection equipment, custom fixtures, positive controls, or CCIT method-development needs. Include the package format, observed failure pattern, and current test method so the application can be assessed more accurately.