Force Decay (Reactive Force Leak Detection), Seal Strength and Vacuum Decay Testing

Force Decay or Reactive Force Leak Detection

What Is Force Decay Leak Detection?

Force decay or reactive force leak detection assesses the seal integrity of flexible packaging, including sachets, pods and pouches. The operator places a test sample in a chamber and evacuates it, causing the package to expand and generate pressure on the chamber’s internal force sensor.

The sensor measures this reactive force to determine leaks. A constant force measurement indicates seal integrity. A minor leak will record an expansive force initially, but this will reduce as the air escapes from the hole and into the chamber. No force measurement represents a gross leak.

Packaging Suitability

Reactive force leak detection is appropriate for the following applications:

• Nonporous flexible food, pharmaceutical and medical packaging with little to ample headspace
• Tyvek® food, pharmaceutical and medical device packaging
• Rigid containers with flexible lid seals
• Sachets, pouches, bags, stick packs and lidded trays made of foils, films or laminates
• Sealed pods with flexible and semi-flexible lids seals, e.g. coffee pods.

Advantages of Force Decay Testing

The force decay testing method is rapid and can detect holes down a size of 10 µm in just a few seconds. Its ability to highlight gross and micron leaks in multiple materials makes it suitable for several applications and industries.

Reactive force testing is also non-destructive, enabling repeatable testing without damaging the sample. A plate inside the vacuum chamber prevents the package from significantly expanding and bursting.

This package seal integrity testing method also requires minimal sample preparation, reducing the risk of operator error.

Disadvantages of Force Decay Testing

Force decay testing can determine the presence of a leak but not its exact location, which would require additional testing.

This method is also limited by the size of the testing equipment, meaning it may not be suitable for large-pack formats like oversized containers.

Finally, reactive force testing depends on accurately measuring the force exerted by a package on the pressure sensor. Regular calibration and maintenance are needed to ensure accurate and reliable results.

Seal Strength Integrity Test

What Is Seal Strength Seal Integrity Testing?

Seal strength integrity testing is widely conducted in the manufacturing, food and pharmaceutical sectors. It assesses the seal strength of packaging comprising rigid and flexible materials, such as ready meals and yoghurt pots.

It involves gripping or clamping each side of a one-inch sealed section of the package using equipment such as the single-column universal testing machine from AML Instruments. This equipment pulls one side of the seal away from the other and measures the maximum force required. With this method, operators can detect weaknesses that may affect the entire production line and ensure the contents are secure and will not be compromised during transportation.

Relevant Standards and Packaging Suitability

• Standard Test Method for Seal Strength of Flexible Barrier Materials — F88/F88M-21
• Standard Test Method for Mechanical Seal Strength Testing for Round Cups and Bowl Containers with Flexible Peelable Lids — F2824-10(2020)
• All forms of packaging in which a seal must be removed to access the product

Advantages of Seal Strength Testing

This method is the only one designed to test seal strength specifically. Simulating the stresses the seal may experience in real-world conditions — including during handling, transportation or usage — enables manufacturers to reduce breakage and ensure the product remains fresh and contamination-free.

Disadvantages of Seal Strength Testing

This testing method measures the integrity of the seal only. It will not detect the presence or locations of leaks or other vulnerabilities within a package. This limitation means the seal strength test is rarely sufficient alone, so other package leak testing methods may be required to ensure quality control.

Seal strength testing is also destructive, as the force applied can break or tear the seal or packaging. When tested on products with a modified packaging atmosphere, this method can expose the contents to oxygen and cause spoilage.

Another disadvantage of seal strength testing is that the operator can be a source of error. Manual handling can impact the repeatability of results, for example, if the operator fails to secure the package between the clamps correctly.

Vacuum Decay Seal Integrity Testing

What Is Vacuum Decay Seal Integrity Testing?

A vacuum decay test is an effective method of evaluating packaging seal integrity, particularly in industries where it is critical that seals are airtight. The operator places the packaging inside a chamber or collapsible bag and evacuates the air to create a vacuum. A sensor inside the controlled environment continuously measures the pressure, enabling real-time analysis.

A pressure drop can indicate a defect, but leaks can be observed visually, too. For example, this leak detection method is used in food processing to test the seal integrity of products containing pockets of air or a modified atmosphere, such as crisp packets. The vacuum will cause the packet to expand. Therefore, a collapse can indicate the presence of a leak.

Relevant Standards and Packaging Suitability

• Standard Test Method for Non-destructive Detection of Leaks in Packages by Vacuum Decay Method — ASTM F2338 – 09(2013)
• Plastic screw-capped bottles containing solids (tablets, capsules and powders) or liquids (with significant gas headspace volume)
• Glass or plastic vials containing liquids (with significant gas headspace volume) or solids (powders)
• Glass or plastic ampoules containing liquids
• Glass pre-filled syringes containing liquids or solids (lyophilised powders)
• Ophthalmic dropper tip bottles containing liquids
• Blow-fill seal bottle or strip containing liquid
• Flexible, nonporous packages, including bags and pouches containing solids (powders and medical devices)
• Sealed cups or trays containing solids (tablets, capsules, powders or devices)
• Sealed empty cups or trays

Advantages of Vacuum Decay Seal Integrity Testing

The vacuum decay package seal integrity testing method is easily adaptable to lab and production environments and detects gross and micron-sized leaks.

It is also non-destructive, which reduces waste and allows the sample to be used or sold. Vacuum decay seal integrity testing is also more efficient than destructive methods, which often require operators to spend time preparing and testing additional samples.

Disadvantages of Vacuum Decay Testing

Like other package leak detection methods, vacuum decay can easily detect the presence of a leak, but its exact location can be hard to determine.

Learn More about Leak Detection and Seal Integrity

Seal integrity testing is pivotal in protecting against leaks or defects and ensuring packaging is safe and effective across multiple use cases and industries. Learn more about leak detection methods and applications by using the links below:

• Learn more about leak detection and seal integrity testing and why it is important
• Learn more about the methods of leak detection and seal integrity testing available
• Learn more about burst, bubble emission and altitude simulation package seal integrity testing
• Learn more about dye penetration seal integrity testing
• Learn more about flow rate seal integrity testing
• Learn more about how to select the right leak detection and seal integrity method for your business
• Learn more about how frequently seal integrity testing should be carried out
• Learn more about how documents and records of seal integrity testing can be stored

Explore Our Range of Leak Detection and Seal Integrity Testing Equipment at LIMAB UK

Our team of product specialists at LIMAB UK get to know the unique needs of your business and provide one-to-one support to find the best package leak detection and seal integrity testing method for you. Request a consultation today by calling +44 (0)1823 668633, emailing hello@limab.co.uk or submitting a contact form.