Leak Testing for Pharmaceutical Products: Methods and Equipment

By Tanner Vandenberg, CEO, FlexPak Leak Detectors Inc.

A pharmaceutical package has to hold its seal from the filling line to the patient. Leak testing for pharmaceutical products is how you prove it did, and which method you choose depends on how much air is inside the package. Leak testing pharmaceutical packages is one test with several methods, not one procedure.

What is a leak test in pharma?

A leak test in pharma puts a sealed package under a pressure differential and looks for the gas escaping through any defect. The package goes into a chamber, the chamber pulls a vacuum, and gas inside the package expands and escapes through any breach in the seal.

The result is a pass or fail on that unit. It tells you whether that specific package held, which is why leak testing sits in batch release and in validation work rather than in continuous monitoring. A leakage test in pharmaceutical production is a sample check, not a screen of every unit.

Which method fits which package

This is the decision that matters, and it turns on headspace, meaning how much gas is sealed inside.

• ASTM D3078, bubble emission. The package is submerged and a vacuum is pulled around it. Gas escapes as a visible stream, so you see the leak and where it is. It needs gas inside the package to work.
• ASTM F2096, internal pressurization. Air is introduced into the package instead of relying on what is already there. This is the one for packages with little or no headspace. It detects to approximately 250 microns with roughly 81% probability, and it is a laboratory and new-material tool rather than a line tool.
• ASTM D5094, dry chamber. No water bath. For liquid-filled and low-headspace formats where submersion is not workable.

Two methods you will see named in pharma literature that FlexPak does not perform: vacuum decay (ASTM F2338) and dye penetration (ASTM F1929). If an auditor has specified either of those by name, a bubble or internal-pressurization chamber is not the answer and we will tell you so.

Leak test procedure in pharma, step by step

1. Select the sample per your sampling plan. Leak testing is destructive on some formats, so the plan matters.
2. Place the package in the chamber and close the lid so it is held under the hold-down plate.
3. Pull the vacuum to your validated setpoint.
4. Hold and observe. D3078 calls for a 30 second hold. A steady stream of bubbles from the seal area is a leak; no bubbles is a pass.
5. Record the result against the unit and the batch.

The part most programs get wrong is the setpoint. A vacuum level chosen because it looks reasonable is not a validated setpoint, and it will not survive a question from an auditor.

Where leak testing fits in a pharma QA program

Leak testing answers one question well and it is worth being precise about which one. It tells you whether the seal on this package holds a pressure differential. It does not tell you the seal’s strength, and it does not condition the package for transit.

Seal strength is a separate measurement, and seal strength testing is where that lives. Transit and altitude stress is a third thing again, covered by ASTM D6653 altitude conditioning.

A program that runs all three knows the seal holds, knows how much force it takes to open it, and knows it survives the trip. A program that runs one and reports it as package integrity is overstating what it has.

Equipment and validation support

A FlexPak Leak Detector runs the bubble emission test in about 30 seconds per unit, with no consumables. Vacuum range is roughly 0 to 27 in. Hg (0 to 90 kPa).

For packages with little or no headspace, the FPIPA adds internal pressurization for ASTM F2096. It runs as an add-on to a chamber you already own or as a standalone unit.

IQ, OQ and PQ qualification support is available, which is usually the part a pharma buyer needs to move an equipment purchase past quality assurance.

Frequently asked questions

What is leak testing for pharmaceutical products?

It is a test that puts a sealed pharmaceutical package under a pressure differential and looks for escaping gas, giving a pass or fail on seal integrity for that unit.

Which ASTM method should a pharma package use?

D3078 bubble emission where the package has headspace, F2096 internal pressurization where it has little or none, and D5094 dry chamber for liquid-filled or low-headspace formats where submersion will not work.

How sensitive is the test?

ASTM F2096 internal pressurization detects to approximately 250 microns with roughly 81% probability. Bubble emission under D3078 is characterised by leak rate rather than a micron figure.

Does FlexPak do vacuum decay or dye penetration?

No. Vacuum decay (ASTM F2338) and dye penetration (ASTM F1929) are not methods we perform. If your specification names either one, a bubble emission chamber is not the right equipment.

Can the equipment support validation?

Yes. IQ, OQ and PQ qualification support is available, and the fully automatic controller logs each run so there is a record to show.

About the author

Tanner Vandenberg is CEO of FlexPak Leak Detectors Inc., which builds the equipment described here at its St. Catharines, Ontario facility. Connect with Tanner on LinkedIn.