Bubble Point Integrity Test: What Is It and What for Use?

The Bubble Point Integrity Test is a crucial method employed across industries like biopharmaceutical, food and beverage, and manufacturing to assess the filtration products’ integrity. By subjecting filters to this test, manufacturers ensure that they maintain their integrity both before and during use.

This test helps ensure that filters maintain their integrity before and during use, preventing contamination and ensuring product safety. Let’s explore what the Bubble Point Integrity Test involves and which specific filter products require this test.

What Is Bubble Point？

Bubble point is a term used in thermodynamics and filtration to refer to the pressure or temperature at which the first bubble of vapor is formed when heating a liquid consisting of two or more components. It is an indirect measurement that provides insights into the largest pore in a filter.

The concept of bubble point is based on the fact that liquid is held within the filter’s pores due to surface tension and capillary forces. By applying pressure or heating, the liquid is eventually expelled from the pores, and the minimum pressure or temperature required to achieve this expulsion is a measure of the pore diameter.

Understanding Bubble Point Integrity Test

One method to test the integrity of a filter is by measuring its bubble point. Typically, this is done prior to installing the filters into the system, but it can be done post-installation with proper plumbing.

To measure the bubble point, the filters need to be installed in a housing and thoroughly wetted with the appropriate fluid. Typically, water is used for hydrophilic filters, while a mixture of alcohol and water is used for hydrophobic filters.

After installing the filter in the housing, the housing is connected to an air source upstream. The downstream line is then directed into a vessel filled with water, where bubbles can be observed.

Gradually increase the upstream pressure, and continue until a steady stream of bubbles is noticed in the downstream vessel. Confirming that this bubble point aligns with the manufacturer’s specifications indicates that the filter is intact and appropriate for use.

Precautions During the Bubble Point Integrity Test Process

To ensure accurate results during the Bubble Point Integrity Test process, it is crucial to observe certain precautions. One important consideration is to use clean and filtered air to prevent any potential damage to the membrane. Contaminants in the air can interfere with the testing process and lead to inaccurate readings.

Additionally, it is important to control the rate at which pressure is applied during the testing. The pressure rate should not exceed five psi (pounds per square inch) per second. Applying pressure too rapidly can disrupt the fluid flow and affect the bubble point measurement, compromising the accuracy of the results.

Another precaution is to maintain the pressure for a sufficient duration before noting the bubble point pressure. It is generally recommended to maintain the pressure for at least 30 seconds. This allows time for the system to stabilize and reach equilibrium, ensuring accurate measurement and reliable results.

Furthermore, it is crucial to check for air leaks throughout the testing process. Any leaks in the system can lead to inaccurate measurements and affect the validity of the results. Therefore, it is essential to ensure that all connections are secure and airtight.

Filtration Products that Require Bubble Point Integrity Test

The Bubble Point Integrity Test is vital for specific filter products such as sterilizing grade filters, membrane filters like cartridge and syringe filters, and small filter assemblies found in disc holder filters and cartridge filter housings.

Sterilizing Grade Filters

Sterilizing grade filters plays a critical role in maintaining the purity of pharmaceutical and biopharmaceutical products. Due to the sensitive nature of these industries, it is imperative that these filters undergo the Bubble Point Integrity Test to ensure their proper functioning and effectiveness.

By subjecting sterilizing grade filters to this testing method, manufacturers can verify their ability to prevent contamination and ensure the integrity of the final product.

Membrane Filters

In various industries such as food and beverage, cosmetics, and biopharmaceuticals, membrane filters like cartridge filters or syringe filters are commonly used. These filters are designed to remove unwanted particulates and ensure product quality. The Bubble Point Integrity test process is crucial in identifying the minimum pressure required for air to pass through the membrane’s tiny pores.

This test helps determine the efficiency of the membrane filters in effectively removing undesired particles, thereby ensuring the reliability and performance of the filtration system.

Disc Holder Filters and Cartridge Filter Housings

Similarly, small filter assemblies, such as those installed in disc holder filters and cartridge filter housings, also require Bubble Point Testing. This testing procedure helps assess the integrity of these filter assemblies and ensures that they are functioning properly.

By subjecting these assemblies to the Bubble Point Test, manufacturers can identify any potential leaks or faults in the system, allowing for necessary corrections and ensuring optimal filter performance.

Conclusion

The Bubble Point Integrity Test is an essential testing process for various filter products across industries, ensuring the safety and quality of various industrial applications.

With the help of this method, manufacturers, like Brother Filtration, can ensure the integrity of their filter products and deliver safe and reliable filtration solutions to their customers, upholding rigorous quality control standards.