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Posted: Sep 02, 2010 09:42 AM	Tested Open Cell with TB coatings mikey... so in a 10-12" application of open cell foam... could we use an "untested" (tested=meaning tb coating over the specific foam,,you know,,,ul1715 or nfpa286) out to 6" and then top with the "tested" 4" (which appears to be the depths of the "tested assembly")brand of open cell foam and the appropriate tb intumescent coating? you see the documents reference "exposed foam",,and the "tested foam" would be the exposed foam.. i am justifying this dialoge in reference to the "flash over point" which is a surface phenom...not deep in the bun of foam situation... (yeah i know...not a chance..rofl) thanx mikey 'dude
Posted: Sep 03, 2010 11:32 AM	foamdude, A really good question. The problem with Open Cell foam in Thermal Barrier type testing is that it shrinks back away from the flame source (while Closed Cell does not), which creates some interesting and complex issues that must be considered in a question like this one. I have seen the shrink back to be between 4-6" in a GOOD test. In a failed one, it is pretty much all gone (burned up, leaving an empty cavity) in the corner, regardless of thickness. This is why the scenario you describe cannot be considered "based on the fact that the 4" foam + coating passed". It is probable that, when it was tested, at the hottest part of the corner, the foam was gone (or close to it) by the end of the test, but since there is NON-FLAMMABLE gypsum or cement board behind it, the contribution to the fire stopped there. Now, if you put unrated foam as you describe behind the 4" "tested" OC SPF + coating, you have a new problem. IF that assembly were tested in a Room Corner test, it is a virtual certainty that the 4" thick "rated" OC foam would shrink back during the test, and the heat of the fire would then be almost directly in contact with the "unrated" OC foam underneath. It would ignite, off-gas, etc... this because with THIS scenario, there is no gypsum or cement board to STOP the shrink back effect at 4". I see that you kind of anticipated my answer might be negative... but these are the facts. As Maxwell Smart used to say... Sorry about that Chief! Mike Kiser

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Posted: Sep 02, 2010 09:42 AM

Tested Open Cell with TB coatings

mikey...

so in a 10-12" application of open cell foam...
could we use an "untested" (tested=meaning tb coating over the specific foam,,you know,,,ul1715 or nfpa286) out to 6" and then top with the "tested" 4" (which appears to be the depths of the "tested assembly")brand of open cell foam and the appropriate tb intumescent coating?
you see the documents reference "exposed foam",,and the "tested foam" would be the exposed foam..
i am justifying this dialoge in reference to the "flash over point" which is a surface phenom...not deep in the bun of foam situation...
(yeah i know...not a chance..rofl)
thanx mikey
'dude

Posted: Sep 03, 2010 11:32 AM

foamdude,

A really good question.

The problem with Open Cell foam in Thermal Barrier type testing is that it shrinks back away from the flame source (while Closed Cell does not), which creates some interesting and complex issues that must be considered in a question like this one.

I have seen the shrink back to be between 4-6" in a GOOD test. In a failed one, it is pretty much all gone (burned up, leaving an empty cavity) in the corner, regardless of thickness.

This is why the scenario you describe cannot be considered "based on the fact that the 4" foam + coating passed". It is probable that, when it was tested, at the hottest part of the corner, the foam was gone (or close to it) by the end of the test, but since there is NON-FLAMMABLE gypsum or cement board behind it, the contribution to the fire stopped there.

Now, if you put unrated foam as you describe behind the 4" "tested" OC SPF + coating, you have a new problem. IF that assembly were tested in a Room Corner test, it is a virtual certainty that the 4" thick "rated" OC foam would shrink back during the test, and the heat of the fire would then be almost directly in contact with the "unrated" OC foam underneath. It would ignite, off-gas, etc... this because with THIS scenario, there is no gypsum or cement board to STOP the shrink back effect at 4".

I see that you kind of anticipated my answer might be negative... but these are the facts.

As Maxwell Smart used to say... Sorry about that Chief!

Mike Kiser

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