Bubble Leak Testing with an Acrylic Vacuum Chamber

Introduction to Bubble Leak Testing

Bubble Leak Testing, also known as Bubble Emission Testing, is an effective and widely used method for leak detection. It helps identify leaks by observing bubble formation when a test specimen is submerged in water. Burhani Engineering Technology manufactures high-quality vacuum leak testing equipment, including vacuum leak testers and vacuum chambers used in this process. This article delves into how vacuum leak testers are employed for seal integrity testing, covering the vacuum decay leak test and pressurized bubble leak test methods, as well as their application in packaging integrity testing.

What Is a Bubble Leak Test?

>A Bubble Leak Test is an essential technique used to perform leakage inspection by detecting bubbles emitted from a test specimen when submerged in water. The test can be conducted using two primary approaches: the vacuum leak testing method (ASTM D3078) and the pressurized leak testing method (ASTM F2096). Vacuum leak testers are typically used for delicate materials, as they apply a vacuum to detect leaks without pressurizing the specimen, offering a safer and simpler approach.

Pressurized Method (ASTM F2096)

>In the pressurized leak test procedure, the specimen is pressurized above the ambient pressure, and any leak allows gas to escape, forming bubbles in the water. This method requires specialized equipment like a pressure leak tester.

• Advantages: The pressurized method provides greater sensitivity to leaks due to the elevated internal pressure, making it suitable for testing materials that can withstand higher pressures.
• Disadvantages: This method is more complex and can potentially damage fragile specimens. It requires additional equipment such as a pressure leak detector and is not ideal for delicate or sealed packaging.

Vacuum Method (ASTM D3078)

>The vacuum leak detection method involves creating a vacuum around the test specimen. This method is favored for package leak detection as it is safer for delicate materials and easier to implement than pressurizing the specimen. When a leak is present, gas from the higher pressure inside the specimen escapes into the vacuum chamber, forming visible bubbles.

• Advantages: The vacuum leak tester does not pressurize the specimen, making it ideal for fragile packaging. It also offers simplicity in setup, with a quick and effective process.
• Disadvantages: The vacuum decay leak test may not detect leaks as small as those detected through the pressurized method, but it is still highly reliable for most applications.

How the Vacuum Bubble Leak Test Works

>The vacuum test relies on a pressure differential. During testing:

1. The specimen is placed inside a vacuum leak test chamber.
2. A vacuum is applied, reducing the pressure inside the chamber.
3. If a leak is present, gas from inside the specimen flows to the lower-pressure area, forming bubbles in the surrounding water.
4. These visible bubbles indicate the presence of a leak and its location.

>The vacuum leak tester for packaging can detect leaks as small as 0.001 inches (0.025 mm) in diameter, though this size is typically irregular and difficult to spot without the use of advanced detection tools.

Accuracy and Comparison of Leak Detection Methods

>Burhani Engineering Technology’s leak detection instruments, including vacuum leak testers and helium leak detection systems, offer high sensitivity for both fine leak detection and gross leak detection. The bubble emission test is accurate to approximately 10⁻³ atm-cc/sec, comparable to other methods such as the pressure decay leak test and air decay leak testing. While the vacuum helium leak detector can detect even smaller leaks, the bubble leak test equipment remains a cost-effective and reliable solution for many applications, including food packaging seal integrity testing and medical device leak testing.

Internal Pressurization Method (ASTM F2096)

In some cases, internal pressurization is used for package seal integrity testing. The test involves inserting a static probe into the specimen and pressurizing it with air. This approach requires a vacuum leak tester and a pressure leak tester to maintain precision. Internal pressurization is ideal for certain packaging integrity testing tasks where the specimen is large or robust enough to handle higher internal pressures.

Advantages of Bubble Emission Leak Testing

• Cost-Effective for Seal Integrity Testing: The vacuum leak tester offers a cost-efficient solution compared to helium leak testing and pressure decay leak testers. It is ideal for testing food packaging seals, blister packs, and pouches.
• Quick and Easy to Perform: The process is simple: submerge the specimen in water, apply a vacuum, and look for bubbles. This method requires minimal training for operators and can be used to test a wide range of packaging materials, including vials, bottles, and blisters.
• Effective for Leak Detection in Packages: The vacuum box testing method and pouch leak testing machine from Burhani Engineering Technology are commonly used for package seal integrity testing. These systems allow for the quick and effective detection of leaks in both commercial and medical packaging.
• Immediate Visual Leak Detection: Bubbles are a direct indicator of leaks, allowing operators to quickly identify the location of the leak and take corrective action.
• Versatile Testing Method: Vacuum decay leak test systems can accommodate a variety of specimen shapes and sizes, such as pouches, vials, and blister packs, making them versatile for different industries.

Vacuum vs Internal Pressurization Methods

>When choosing between vacuum leak detection methods and internal pressurization, consider factors such as the type of material being tested and the sensitivity required. Both methods have their advantages:

• Vacuum Leak Test: The vacuum testing machine is ideal for delicate materials and is simpler to implement, requiring fewer components like vacuum pumps and vacuum leak detection equipment.
• Internal Pressurization Method: Provides more precise control of pressure and is better suited for larger, more robust packages that can withstand pressurization without damage.

Limitations of Bubble Leak Detection

• Minimum Detectable Leak Rates: The vacuum decay leak test typically detects leaks down to about 10⁻³ atm-cc/sec, making it suitable for many applications, but helium leak detection methods are more effective for smaller leaks.
• Inapplicable for Permeable Materials: Bubble leak tests are ineffective for permeable materials, as air continuously escapes, making it hard to localize the leak.
• Subjectivity in Visual Detection: Detecting small leaks through bubble formation is somewhat subjective and depends on the operator’s ability to identify small bubbles.
• Air Depletion in Specimen: If no external air is supplied, the internal air pressure of the specimen may decrease over time, reducing the effectiveness of the vacuum leak test.

Conclusion

Burhani Engineering Technology offers a range of vacuum leak testers and helium leak detectors designed for accurate and efficient leak testing. Whether you're testing vacuum bags, vials, or medical device packaging, our vacuum leak detection instruments are engineered for precise and reliable results. Our vacuum leak test equipment, including pouch leak testing machines, vacuum leak test chambers, and packaging leak testers, are built to meet ASTM D3078 and other industry standards, ensuring that your packaging maintains the highest integrity.

For more information about helium leak testing, vacuum decay leak tests, and other leak detection techniques, get in touch with Burhani Engineering Technology today. Our advanced solutions, such as the Haug Pack Vac Leak Detector and Leybold Leak Detectors, are trusted by industries worldwide for their accuracy and reliability in non-destructive leak testing.