Package Leak Detection: Best Methods for the Food and Pharma Industries

It’s the email every quality manager dreads. A customer has just opened a multipack of crisps and found half the packets stale. Or a hospital pharmacy has received a shipment of blister packs with compromised seals. 

That one bad experience can send a regular buyer - whether a consumer or a procurement team - straight to a competitor’s product. In minutes, years of brand trust can start to unravel. And winning clients back is far harder than keeping them in the first place. 

It’s a scenario we see time and again, which is why effective package leak detection is essential. It stops problems before they leave the factory, protecting products, brand reputation, and repeat sales.

Risks of Undetected Leaks

Package leak detection is the process of assessing packaging for defects, such as punctures, pinholes, channel leaks, or mechanically weak seals, that could allow contents to escape or contaminants to enter.

In the food industry, undetected leaks can lead to:

• Contamination: Oxygen, moisture, or microorganisms can compromise food safety.
• Reduced shelf life: When modified atmosphere packaging (MAP) loses its protective gases, food stales and spoils more quickly.
• Regulatory non-compliance: Failure to meet BRC, IFS, HACCP, or ASTM standards can result in failed audits and rejected shipments.
• Costly waste: Spoiled product, production downtime, and reprocessing drive up costs.
• Lost sales: Quality issues undermine consumer confidence and damage brand reputation, driving consumers to competitor products.

In the pharmaceutical industry, the impact of undetected leaks includes:

• Loss of sterility: Seal breaches in blister packs, sachets, or vials compromise Container Closure Integrity (CCI), allowing microbial contamination and risking patient safety.
• Active ingredient degradation: Oxygen and moisture exposure can reduce a drug’s potency and stability.
• Regulatory breaches: Failing to meet GMP Annex 1, USP <1207>, and ASTM standards can result in failed inspections and stop distribution.
• Lost contracts: Quality issues can lead healthcare providers to switch suppliers.

Package Leak Detection Methods

There are many ways to test seal integrity, from fully automated systems to simple manual setups. However, not all leak detection methods offer the accuracy, repeatability, and compliance needed for food and pharmaceutical products.

We still encounter businesses relying on manual “squeeze and dunk” or quick visual checks carried out by operators. These approaches are subjective, unstandardised, and prone to error, often allowing small but critical leaks to go undetected.

The methods we describe below are proven, standards-backed approaches that deliver consistent, repeatable results.

Vacuum Decay

How it works

Vacuum decay is a non-destructive package leak detection method used in both food and pharmaceutical manufacturing.

The package is placed in a vacuum chamber or a flexible membrane bag, where air is evacuated to create a controlled vacuum environment. Sensors continuously monitor pressure; any drop indicates a leak.

Benefits

• Non-destructive.
• Detects both gross (large) and micron (invisible) leaks.
• Can be used for detailed testing in the lab and routine sampling during manufacturing.
• Recognised in ASTM standards (e.g., F2338) for pharmaceutical and medical device packaging.

Limitations

• Cannot pinpoint the exact location of a leak.
• Requires a tight fit between the product and the chamber/membrane; any excess headspace outside the pack can reduce sensitivity.
• Equipment must be calibrated regularly to maintain compliance with packaging testing standards.

Best for

• Pharma: Vials, ampoules, syringes, blister packs.
• Food: Pouches, lidded trays, bags with measurable headspace.
• Rigid and semi-rigid containers requiring container closure integrity (CCI) verification.

Constant Flow

How it works

Constant flow, also called “flow rate seal integrity testing”, is a low-pressure method designed to detect package leaks accurately in flexible packaging, including modified atmosphere packaging (MAP), blister packs, and pouches.

The package is inflated to a low, controlled pressure (usually around 30 millibar). Rather than sealing the system, the test maintains this exact pressure throughout the cycle. 

The instrument measures how much air is needed to keep the pressure stable. If no additional air is required, the package is leak-free, while continuous air input indicates a leak. The flow rate can be used to estimate the hole size for precise measurement.

Benefits

• Highly accurate.
• Quantifiable leak rates offering clear pass/fail thresholds.
• Faster, cleaner, and less labour-intensive than other methods.
• Suited to all container formats.
• Adjustable test pressure and sensitivity settings; ideal for delicate seals and recycled or lightweight packaging materials.
• Audit-ready, traceable data. Records can be stored and reviewed later for compliance or troubleshooting.
• Compliant with BRC, IFS PACsecure, and HACCP and  USP <1207>.

Limitations

• Destructive.
• Cannot identify the physical location of a leak.
• Higher equipment investment.

Best for:

• High-volume production lines needing fast, objective, audit-ready results.
• Food: Flexible MAP packs such as snack bags, salad pouches, ready-meal trays.
• Pharma: Flexible blister packs, sachets, medical pouches.

Force Decay (Reactive Force Leak Detection)

How it works

Force decay - also called reactive force leak detection - measures how a package reacts under vacuum. It’s commonly used in pharma for container closure integrity (CCI) testing and in certain food safety applications where non-destructive testing is preferred.

The package is placed in a vacuum chamber with an internal force sensor. As the air is evacuated, the package expands against the sensor, generating a measurable force.

If the seal is intact, the force remains constant. If there’s a leak, the force decreases as gas escapes from the package into the chamber.

Benefits

• Non-destructive with rapid test times.
• High sensitivity (down to ~10 microns).
• Minimal sample preparation reduces operator error.
• Detects both big and small leaks across multiple materials.
• Aligned with ASTM practices.

Limitations

• Cannot determine the exact location of a leak.
• Restricted by the size of the testing chamber; can’t be used for large-format packs.
• Relies on accurate force sensor calibration to maintain sensitivity.
• Not suited for applications with minimal headspace.

Best for

• Situations requiring non-destructive testing with high sensitivity for applications with defined headspace.
• Nonporous flexible packaging (sachets, pouches, stick packs, lidded trays) and rigid containers with flexible seals.
• Pharma: Small pouches, stick packs, Tyvek® medical device packs.
• Food: Sachets, pouches, lidded trays with flexible seals.

Pressure Decay

How it works

Pressure decay is a traditional package leak detection method widely used for rigid containers, such as metal tanks and pipes.

The package is pressurised with air to a set level. Then, the system is sealed, and the internal pressure is monitored over a set period. A pressure drop indicates a leak.

Benefits:

• Well-established method with simple instrumentation.
• Works well for rigid or semi-rigid containers.
• Quantitative results provide measurable leak rates.
• Compliant with ASTM F2095 for flexible packaging.

Limitations

• Longer cycle times compared to other methods.
• Not suitable for packages with delicate seals or flexible materials. High test pressures can damage the packaging, causing real leaks or false leak indications.
• Provides no visual indication of leak location.

Best for

• Rigid or semi-rigid containers like bottles, jars, and trays with lidded seals.

Bubble Emission

How it works

Bubble emission, often called the “water bath” or “dunk test,” is a destructive packaging testing method used in both food and pharma.

The package is submerged in water inside a vacuum chamber. As the vacuum is applied, any gas escaping from the package forms visible bubbles. The operator notes the bubble’s origin to pinpoint the leak location.

Benefits

• One of the few methods that visually pinpoints the leak location.
• Simple, low-cost equipment.
• Widely recognised and covered under ASTM standards.
• Works for a wide variety of pack sizes and formats.
• Recognised in ASTM F2096 for gross leak detection in flexible packages.

Limitations

• Destructive.
• Subjective. Results depend on the operator’s observation and small leaks below ~30 microns are difficult to see.
• Messy and time-consuming. Cleaning the chamber and disposing of contaminated water can slow production.
• Contamination risk. Submerging a product in water can create biohazard or cross-contamination concerns.

Best for

• Food & pharma: Any packaging where leak location must be identified.
• Validation and investigation stages rather than full-line screening.
• Troubleshooting sealing equipment or process issues.

Dye Penetration

How it works

Dye penetration is a destructive package leak detection method often used in pharmaceutical applications, especially for blister packs and pouches where bubble emission may not be practical.

The package is exposed to a coloured dye solution, typically methylene blue, for a set period. This penetrates any seal defects or microchannels. The operator inspects the package - visually or under magnification - to identify and locate leaks.

Benefits

• One of the few methods that identifies the leak location.
• Effective for small-format pharmaceutical packs like blisters.
• Visual confirmation of leaks even in complex seal patterns.
• Straightforward to implement with minimal equipment.
• Meets ASTM F1929 standards for detecting seal channel leaks in porous and nonporous packaging.

Limitations

• Destructive.
• Subjective, operator-dependent.
• Limited sensitivity for very small leaks.
• Cycle times can be longer compared to non-destructive methods.
• Contamination risk. Dye requires careful cleaning and can leave residue.

Best for

• Pharma: Blister packs, small medical pouches.
• Packaging with minimal headspace where bubble emission is impractical.
• Validation protocols or troubleshooting small-format seals.

Burst Test

How it works

The burst test is a destructive packaging testing method used to measure the maximum seal strength of a package.

The package is pressurised with air or gas until the seal or packaging material fails. The system records the pressure at the point of rupture.

The test can be run in a restrained setup, where the package is held between plates to simulate the constraints of a filled package, or in an unrestrained setup, where the package is free to expand fully during pressurisation.

Benefits

• Only method specifically designed to measure seal strength.
• Simulates real-world stress conditions during handling and transport.
• Meets ASTM F1140/F2054 for package strength and integrity testing.

Limitations

• Destructive.
• Does not detect micro-leaks under normal operating conditions.
• Not suitable for every packaging format, particularly rigid containers.

Best for

• Validating packaging design and sealing processes
• Food & pharma: Flexible packs, pouches, lidded trays where seal strength must be measured.
• Packaging design validation, process qualification, and QA audits.

At-a-Glance: Package Leak Detection Methods

‍

Choosing the Right Method

The best package leak detection method depends on your packaging format, required sensitivity, and more.

• Destructive vs non-destructive: Choose non-destructive methods (vacuum decay or force decay) when you want to avoid waste and keep the product saleable. Use destructive methods (bubble emission, dye penetration, burst, constant flow) when you need to pinpoint leak location, validate seal strength, or troubleshoot a sealing issue.
• Packaging type: For small packs like blister strips and sachets, use dye penetration. For other formats, choose either vacuum, pressure decay, constant flow, or bubble emission.
• Sensitivity: For pharmaceuticals, aim for around 5 micron detection; for food, 10 micron is typically sufficient.
• Inline vs offline: Inline testing is generally limited to MAP gas analysis. Use offline methods for full seal integrity testing.
• Hygiene and cleanrooms: When operating in wet environments or cleanrooms, ensure equipment is either IP-rated for washdown or installed with suitable protection.

Key Concerns When Selecting a Leak Detection Solution

• Accuracy: Choose a method proven to minimise false positives and false negatives, so you prevent issues.
• Speed and throughput: Match the testing method to your production rate; high-speed lines need methods that keep up without creating bottlenecks.
• Packaging versatility: Select equipment that can handle all your current formats and any planned changes without complex, time-consuming changeovers.
• Equipment maintenance and calibration: Work with suppliers who offer reliable servicing, and cost-effective calibration.
• Data traceability and audit readiness: Use systems that securely store test results in an accessible format so you’re always prepared for audits.

Key Standards in Package Leak Detection

Leak detection testing for food and pharmaceuticals must align with recognised standards to ensure consistent, auditable, and regulator-approved results.

• Food: BRC Global Standards, IFS PACsecure, and HACCP for seal integrity. ASTM methods (e.g., F2096 for bubble emission) for repeatable testing protocols.
• Pharma: GMP Annex 1 and USP <1207> for Container Closure Integrity (CCI). ASTM F2338 (vacuum decay) and F1929 (dye penetration) for validation and quality control.

Following these standards also helps guarantee product quality and maintain or strengthen brand trust.

The Most Effective Seal Integrity Strategy for Food and Pharma

For most flexible food and pharmaceutical packaging - especially modified atmosphere packaging (MAP) - the most effective approach combines constant flow with bubble emission testing. 

This two-step process ensures seal integrity and validates seal strength, giving manufacturers the confidence that packaging can both prevent leaks and withstand real-world handling, transport, and storage.

Step 1: Screen with constant flow

Constant flow quickly and precisely identifies whether a leak is present without damaging the pack or slowing production. At the same time, it produces audit-ready data that can be stored and reviewed later. 

Step 2: Confirm with bubble emission

If a leak is detected during constant flow testing, bubble emission can pinpoint its exact location. This visual confirmation helps identify seal problems so they can be addressed immediately.

Why it works

• Fast and accurate. Only a small fraction of packs reach the water bath, reducing mess, waste, and downtime.
• Clear results. Delivers quantitative results for compliance and visual proof for troubleshooting.
• Standards compliant. Meets HACCP, BRC/IFS, GMP Annex 1, and ASTM standards.
• Integrated efficiency. Devices such as the TPC can carry out constant flow, and also have the option for integrated gas analysis tests, reducing operator input, cutting pack waste, and increasing efficiency.

While other methods have their place - such as force decay for small blisters and vacuum decay for rigid containers - this two-step process offers the ideal balance of efficiency, sensitivity, and leak location for flexible food and pharmacautical packs.

Industry Trends

Several developments are shaping the future of package leak detection in food and pharmaceutical manufacturing. 

One clear trend is the shift toward automation, with increasing interest in non-destructive systems that deliver instant results, reduce waste, and keep pace with high-speed production lines. 

At the same time, the move to recycled and recyclable packaging materials has created new challenges. These materials often lack the structural consistency of conventional films, making testing more critical than ever. They sometimes require tailored sensitivity settings or lower test pressures - achievable with methods like constant flow - to prevent damage during inspection.

Another change is the growing demand for integrated, multi-parameter systems that combine leak detection with residual gas analysis. These provide more data in a single test cycle and support both seal integrity and food preservation monitoring.

Find the Right Solution for Your Packaging

As we’ve seen, every packaging format presents its challenges, and the growing shift to recycled and recyclable materials adds another layer of complexity. Choosing the wrong package leak detector wastes time, money, and product.

That’s where we can help. As specialists in package leak detection across food and pharma, we have every major testing method in-house. We can help you optimise your current processes or guide you through the transition to new recyclable packaging, ensuring it meets seal integrity standards without slowing production.

Send us your packaging, and we’ll run free leak testing on a batch using multiple methods. We’ll capture videos, share the results, and talk you through the pros and cons of each approach for your specific application, so you’ll know exactly which method delivers the accuracy, speed, and compliance your industry demands.

Give us a call to discuss your requirements and book a free, no-obligation package leak detection test.