On Tue, 16 Nov 2004 09:53:19 -0500, "J. Clarke"
wrote:

Nor does a commercial DC. It's not the volume that's the issue, it's
the energy per discharge.

You're right that it's not the volume, it's the concentration.

It's the concentration and the energy. If there's inadequate energy
in the discharge, it won't ignite. If the concentration is inadequate,
it won't propagate.

However, even low concentration is not a guarantee of safety for wood
dust handling. There's a problem with smouldering and a burning
particle _may_ settle out in a dead-air zone where there's likely to
be a build up of other dust. In forensic examinations of many dust
collector fires, they began not in the filter or the collecting bin,
but at stagnant corners and sudden pipe expansions.

For a real treatment of this problem, read Luttgens & Wilson's
"Electrostatic Hazards" or a similar industry-standard handbook. I
still haven't found one that has evidence of static discharge caused
fires in wood dust.
--
Smert' spamionam