Flexible Package Bubble Leak Testing: Detecting Leaks by Internal Pressurization

The purpose of bubble leak testing is to detect gross leaks in packaging. Detecting gross leaks in packaging by internal pressurization is also called the bubble test. This packaging test type is primarily used for tray/pouch packaging and can detect leaks as small as 250 microns. Bubble leak integrity testing is destructive, thus, it requires entry into the package to supply internal air pressure.

As a leader in package testing, Keystone understands the importance of bubble leak testing. Our knowledge of packages has allowed us to create a streamlined approach to package validation. Keystone Package testing walks customers through the process from test plan to test report.

If you are ready to start your bubble leak package compliance testing, request a quote. Have questions about leak integrity testing? Contact us to receive more information.

Why is Bubble Leak Package Transportation Testing Important?

Bubble leak testing, also known as the bubble emission test, is a type of integrity testing used to evaluate the seal strength and integrity of flexible packages, such as pouches, sachets, and bags. During the manufacturing and packaging process, it is essential to ensure that these packages maintain their integrity to protect the contents from potential contamination, spoilage, or damage.

Product Safety: Bubble leak testing helps ensure that the packaging is free from leaks or defects that could compromise the safety of the product. For items like food, pharmaceuticals, and medical devices, maintaining product safety is critical to prevent potential harm to consumers or patients.

Quality Assurance: By identifying and fixing leaks or weak seals early in the manufacturing process, bubble leak testing contributes to maintaining consistent product quality. It helps prevent defects from reaching the market and ensures that customers receive products that meet the highest quality standards.

Shelf Life and Product Freshness: Leaky packages can allow air, moisture, or contaminants to enter, which may adversely affect the product’s shelf life or freshness. Proper package integrity testing helps extend the product’s viability and maintains its attributes over time.

Regulatory Compliance: In industries like pharmaceuticals and medical devices, regulatory bodies set strict standards for packaging integrity to ensure the safety and efficacy of the products. Bubble leak testing helps companies comply with these regulations and avoid potential legal and financial consequences.

Cost Savings: Identifying and resolving package integrity issues early in the production process can save costs associated with product recalls, waste, and rework. It also reduces the risk of liability claims and damage to brand reputation.

Customer Trust: Consumers expect products to be properly sealed and protected. Ensuring package integrity through testing fosters trust and confidence in the brand, leading to increased customer loyalty and positive brand perception.

Bubble Leak and Bubble Emission Test Process

Before the start of the test, several specimens are chosen to permit an adequate determination of representative performance. In most cases, conditioning is to be at equilibrium with normal room temperature.

First, the package is inflated underwater. The inflation is to a predetermined pressure. Next, the package is observed for leaks. Failure is indicated by a steady stream of air bubbles.

The sensitivity of this test is dependent on two primary factors. The differential pressure can be increased or decreased. It is important to have repeatable results. Therefore, establishing a test pressure for each package is important. The method of pressurization, size, and the material will also play a factor in attaining repeatable results.

Higher pressure increases sensitivity. Likewise, lower pressure reduces sensitivity. The use of a bleed-off control valve with a pressure monitoring device will aid in stabilizing the test pressure. This assists in reducing excessive pressurization.

There are three primary pieces of equipment necessary to complete bubble leak testing.

  1. A pressure delivery system. This system includes a pressure monitoring gauge and bleed-off control valve. The system must be capable of delivering air at a pressure of 0-50 mbar.
  2. A needle. This package puncturing device allows the insertion of air from the pressure delivery system.
  3. A water container. The device being tested must be covered with at least one inch of water.

Upon completion of testing, a report is issued. This report provides the following information. 

  • The date, operator’s name, and package type
  • Any identification numbers such as serial numbers
  • The defect size used to establish the test sensitivity
  • The test pressure and use of blocking agents, if any
  • The total number of test packages
  • The number of packages that passed
  • The number of packages exhibiting leaks and the location of each leak

Bubble Leak Test: Flexible Package Integrity Testing

Keystone’s Bubble Leak Testing Equipment and Capabilities

Keystone Package Testing utilizes numerous pressure delivery systems, vacuum chambers, and open/closed package test fixtures to provide expert package integrity testing. Our dozens of thermal chambers range from reach-in to large walk-in chambers up to 1,300 cu. Ft.

Additionally, we own shakers up to 12 kips, and multiple compression/tensile testers. Keystone offers complete pack-out services and testing for all types of flexible and rigid packages.

ASTM F2096 Bubble Leak Pressurization Testing

Bubble leak testing to ASTM F2096 can be applied to many different packages. Large and long packages that do not fit other package integrity test methods can be tested to this standard. Bubble leak is also a good fit for packages with unique sizes and shapes.

ASTM F2096 is ideal for medical packaging. However, this test standard has not been evaluated for use with porous materials other than spun-bonded polyolefin or with nonporous packaging.

ASTM D3078 Bubble Emission Testing

ASTM D3078 detects gross leaks in flexible packaging containing a headspace gas. Small leaks may not be detected by this procedure.

The test specimen is first submerged in a fluid contained in the vessel within the vacuum chamber. Next, a vacuum level is chosen to optimize the sensitivity of the test. The vacuum is then released after a certain amount of time and the unit is examined for the presence of test fluid in the specimen. If there are no bubbles observed and no test fluid is found in the specimen, the test unit has passed the test.

Expert Bubble Leak and Bubble Emission Package Transportation Testing

Keystone Package Testing partners with customers to achieve package compliance. Our accurate test reports are delivered quickly and our proven process helps avoid product launch delays. In addition to bubble leak and bubble emission testing, Keystone has a full scope of expertise including compression, drop, and accelerated aging

As experts in medical package testing, we know the appropriate test pressure to use. We also understand and can explain which packages meet the requirements and which ones do not. Our lab is ISTA 17025 and ASTM certified.

Request a quote to experience the Keystone Compliance difference. Contact us to learn why we are one of the fastest-growing package test labs in the country.


Interested in the EMC/EMI, climatic, dynamic, shielding effectiveness, or IP Code testing of a product? Follow the corresponding links or www.keystonecompliance.com for more information.