SpudFiles

Would O-Rings melt inside of a combustion cannon when it's fired?

I don't think so,
Combustion is quite hot but fast.
If you don't believe me make small test cannon and put O-Ring inside then will you know.

Probably not, although that question is far too open-ended to have a definite answer - there are some circumstances in which o-rings could melt or catch fire.

If the O ring isn't exposed to gasses at any velocity (sealing a bolt for instance) then it won't see much heat at all, however if gasses will pass over it then depending on the material, it may erode. That's because more gasses will come in contact with it, and that'll mean more heat can be transferred to it, gasses are normally good insulators, so exposure to static gasses won't cause much trouble.

Even chamber fans don't burn:

[youtube][/youtube]

PVC doesn't burn, or melt, so O-rings won't either. Indeed a PVC closed chamber doesn't even warm up significantly during and after firing.
http://www.inpharmix.com/jps/Chamber_Temperature.html

jimmy101 wrote:PVC doesn't burn, or melt, so O-rings won't either. Indeed a PVC closed chamber doesn't even warm up significantly during and after firing.
http://www.inpharmix.com/jps/Chamber_Temperature.html

EDIT: didn't realize who I was talking to before I post so you probably knows more than me about this matter, bellow it's just my personal idea.
Because plastics are bad heat conductors, same reason why your cooking pan handle has plastic cover. A metal chamber will become warm after shots, even though not much either because it's generally thick (a considerable amount of material) and the short burn doesn't provide enough energy to heat it up.
The o-ring I used to seal burst disc on my hybrid often shows signs of burning after a couple shots, nothing big though.