In October 2007, the International Maritime Organization (IMO) Sub-Committee on Fire Protection released a formal proposal to amend MSC/Circ. 799 due to concern regarding the ability of alcohol-resistant (AR) protein-based foam to perform effectively on alcohols or other polar solvents. These proposed amendments, among many others, were approved and released by the IMO Maritime Safety Committee in June 2009 in the “Revised Guidelines for the Performance and Testing Criteria, and Surveys of Foam Concentrates for Fixed Fire-Extinguishing Systems,” which can be found in the annex of MSC.1/Circ.1312. These revisions require alcohol-resistant and protein-based (including AR fluoroprotein-based) concentrates to be annually subjected to a small-scale fire test as well as a stability test with acetone.
Dyne performs both an acetone stability test and an alcohol-resistance fire test, the isopropyl alcohol (IPA) burnback, for every AR protein-based foam that is tested to IMO 1312. In the acetone stability test, the foam is directly exposed to the acetone solvent for several minutes. This test does not include an ignition source, but is based on visual degradation. A foam will fail this test if it dissolves into the acetone too quickly.
Similarly, the IPA burnback test directly exposes the foam to the IPA solvent for several minutes. Once the exposure requirement is reached, an ignition source is introduced at a preexisting hole in the center of the foam where it ignites the solvent. At this point, the foam has to stay sufficiently intact on the IPA solvent to fight the fire. A foam will fail this test if it does not resist the fire long enough.
In general, AR protein-based foams tend to perform better on the acetone stability test than on the IPA burnback test. One major difference is the solvent used. Acetone has a higher polarity index; however, since IPA is chemically classified as an alcohol, it is important to use this solvent in an alcohol-resistance fire test. The more important difference is the flame in the IPA test, which works against the foam. When foam fails either of these tests, it means the foam did not perform well on alcohol/polar solvents and therefore is not expected to adequately fight fires on such solvents in the field.
There are many factors that may contribute to a foam sample degrading more quickly than expected. IMO MSC.1/Circ.1312 Annex Section 4 states that “particular installation conditions (excessive ambient storage temperature, contamination of the foam concentrate, incomplete filling of the tank, etc.) may lead to an abnormal ageing of the concentrates.” Refer to the manufacturer’s datasheet for the storage specifications for your foam concentrate.
If you have any questions about acetone stability, IPA burnback, or any other test, our staff chemists are ready to answer your questions. Call Dyne at (800) 632-2304 or email, firstname.lastname@example.org, for assistance with understanding your test results.
By Erin Miller, Chemist