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"Testing Fluid-filled Bags"

What is the best method of inspection and testing a pouch that contains 'fluid' inside? Currently we have on-site both burst test and seal peel capabilities; however, the use of these test methods will be quite 'messy' (especially burst).

Last Updated On February 8, 2013

There are no standardized test methods in the medical device or pharmaceutical industry specific to testing fluid filled bags. The ISO 15747 Plastic containers for intravenous injection provides some level of information for guidance; however, even in this standard there are gaps in the specifics of testing.

Within this document is a test for pressure and leakage that is performed after exposure to temperature stability conditions. It subjects the bag to an internal pressure of 50 kPa. The bag is placed between two parallel plates so the pressure can be applied and maintained for 15 minutes. It is not clear how the pressure is applied, nor what the plate coverage of the bag should be. An alternative test deemed “equivalent” in the document instructs the tester to use an “external pressure device, such as a pressure cuff” to apply pressure. How one determines that the equivalent internal pressure has been achieved is unclear. Leaking is checked by visual inspection. Typically, these tests are used to develop more detailed internal test methods for companies that produce bags for the fluid bag market. For example, a pressure cuff may be used to simulate the manipulation of an IV bag that is hand pressured to increase flowrate. Another example is a crush-style burst test where the two plates are compressed onto a bag until it fails. To avoid exposure to the fluid and the cleanup after this test, the bag is sealed into a larger outer clear bag before being put into the crush burst tester.

This standard also defines a bag strength drop test where height of drop is based on the nominal capacity of the container; however the number of drops and visual detail to be recorded is not identified. This again is a basic method that is used to create the defined in-house challenges to package material and seal strength. Once a height for the drop test is determined, repetitive drops are done to test all sides.

Ship testing methods such as ASTM D4169 identify assurance level drop heights based on shipping weight, number and sequence of drops and orientation of the unit on impact. While this document is designed to challenge products in distribution cycles, it is also used to help guide and support development of test protocols for the drop test of fluid bags.

The ASTM standard test methods may also provide a means to assess bags. Although they are not specifically written for fluid bags, the methods can be adopted and validated in-house once modified for use. For example, methods defined for pressure decay of unfilled packages such as ASTM F2095 – 07e1 Standard Test Methods for Pressure Decay Leak Test for Flexible Packages With and Without Restraining Plates and ASTM F2338 – 09 Standard Test Method for Nondestructive Detection of Leaks in Packages by Vacuum Decay Method. Other non-standardized approaches include leak testing where a dye is added to fluid in the test bag. When placed in water under vacuum a leak is detected when colorant escapes into clear water.

The key point here is that there is a gap in the existence of standardized methods for testing these fluid bags. Given the need to modify the intended use and the degree of challenge in existing standards to fill this void, it should be considered that new test methods be written specific to these products. These methods should then be proposed to organizations such as ASTM for building consensus standards in flexible barrier packaging.