[Beowulf] materials for air shroud?

mathog mathog at caltech.edu
Mon Sep 19 08:40:03 PDT 2011


On Sat, 17 Sep 2011 18:53:15 +1000, Richard Windsor wrote:
> I'm sorry but I have to have a quiet chuckle here. The ignition
> temperature of cardboard at 420 C to 430 C is a significantly higher
> that the melting point of solders commonly used in the electronics
> industry that run from 364 C to 418 C. Your poor little processor 
> will
> be in a hot bath up to its neck long before there is any smoke.
> By the way, my cardboard shrouded processor has been running,
> virtually non-stop for over 3 years at about 60 C

Spontaneous ignition from heat isn't going to ignite the cardboard.
However, a spark is well above the ignition temperature, and sparks
are a real possibility on short circuit or component failure in
electronic equipment.  A small number of sparks are not likely to 
ignite
most plastics, but they may ignite paper products.  The difference 
being that
the plastic adjacent to a spark will usually melt, spreading the energy 
around
and keeping the peak temperature below the ignition point.  
Cardboard/paper have
no such mechanism, and so a cellulose fiber in contact with a spark can 
easily
rise above its ignition point.

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech


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