IMO indicates the applicable standard for foams to be used in fighting ship fires.
For certifying low expansion foams (IMO Msc/Circ.1312), a square tray is used with a gentle application against the backboard. The difficulty of this test resides in the foam sealing the edges (as the sea water “dries” the foams) and in the very demanding level of burnback resistance.
When it comes to high expansion foams (IMO Msc/Circ. 670) for the extinguishing systems in the engine rooms, a high expansion index along with a slow drainage time and structural stability of the foam are the main requirements.
The more adequate combination for this would be a Newtonian AR-AFFF at 1% for low expansion (deck fires, tugboats) and a high expansion foam at 2% (for engine rooms).
We believe that a fire test should be mandatory when revising the foams used under IMO Standard and not only the physical-chemical properties like pH, density, etc.