Is there a standard for bubble emission testing that does not require using something like polycrylic to mask the surface? If so, what is the difference between standard FPA SPMC 005-96 and a newer one? Is there a bubble emission standard for testing vacuum-sealed pouches?
There is an ASTM bubble emission test for flexible medical device packaging that uses internal pressurization to detect gross leaks in tray or pouch packages. (F2096-04 Standard Test Method for Detecting Gross Leaks in Medical Packaging
by Internal Pressurization (Bubble Test)) This document, developed initially from the SPMC method, was expanded to identify through round robin testing the precision, bias and sensitivity level of the method. In the scope of the test method,
which is downloadable from the ASTM website, it states the sensitivity to be at “250 _m with an 81 % probability.” This sensitivity level is what is behind using “gross leaks” in the description of the standard. It is specific to the use of the porous spun-bonded polyolefin material commonly known at Tyvek®. Nonporous materials were not part of the round robin testing. Any masking that is
done can have an effect on the ability of the user to recognize pinholes in the material surface. There are guidelines to help the user identify how to establish a pressure that does not push the package past the Tyvek® “bubble point” where
bubbles appear all over the porous surface. As an alternative, the ASTM D3078-02 Standard Test Method for Determination of Leaks in Flexible Packaging by Bubble Emission uses a vacuum chamber. This standard also uses the term “gross
leaks” to define the sensitivity level.
Vacuum sealed pouches might require a different approach. The first method (F2096) breaks the vacuum and inflates the package. This may give you an answer on the package integrity but is probably not the information you would be looking for to determine the effectiveness of the vacuum packaging. Vacuum sealed packages indicate a breach of integrity by losing vacuum and by returning in part or entirely to ambient air pressure. Depending on the degree of vacuum packing, if
the leak is large enough the change in appearance in the vacuum pack may be visible in a short period of time. If the leak is very small, it may take some time for the vacuum to be lost and for the change in appearance to be significant enough to
catch in inspection. Vacuum or pressure decay (both non-destructive) tests function by creating a pressure differential. With the first vacuum is taken low enough to allow any remaining air in the package to expand against any pinholes or channel. If there is no gas within the package to create the pressure against the hole, this will not be an effective test. The alternative would be to increase the pressure outside the package to encourage air to “push through” any defects. There are many issues that can come up with either choice- amount of vacuum inside the package, the package design, shape or configuration, the flexibility of the materials all of which need to be taken into consideration. There are test equipment companies that can help you find the right approach based on the specifics of your package and most have websites that are available on the internet.