Foam insulation

[ranman]

Good evening, I am building a new smoker out of an old commercial fridge. (See "wall thickness" post for more info).
It has 3' thick wal skinned with aluminum and sparay foam insulation (I believe urethane).
This insulation is the main structural support with no framework inside.
I have put a piece of the foam n the oven at 300 degrees F for 2 hrs with no change to it. I then bumped it up to 500 F (why so high I'm not sure). It turned brown but did melt after around 15 min. I left it for around 1 hr. no change.
I am now trying a piece at 350 and it has been in for 30 mins and it is still pale yellow no change.

I will leave this for a few hrs and see. Most of my smoking will be 160 and under with the odd occasion of 220-225 can anyone experienced this or see it as being a problem?

Thanks
Randy

[Gizmo]

No experience here but if it holds out at 350 to 400 deg, you should be good.  The best would be to find out what the foam is and look up the chemical properties including toxins on a material safety data sheet and what decomposition products are produced with fire (heat).

[manxman]

The best would be to find out what the foam is and look up the chemical properties including toxins on a material safety data sheet and what decomposition products are produced with fire (heat).

I think this is very good advice, the foam could just start to give off toxins before any physical signs of burning.  :o

[3rensho]

I second Manx.  The insulation could very easily be out gassing harmful chemicals without burning.  Might well give an off taste as well.  Always good to err on the side of caution.

Tom