[TheForge] Re: coal forge flues

[Mike Spencer]

Bruce wrote:

> What you want to do is convince him that the forge
> flue will never get as hot as a wood stove. 

In particular, neither a coal forge nor a propane forge will coat the
inside of the flue with "creosote" -- highly inflammable wood
distillates that are volatile at stove-fire temps and solid at lower
temps.  The really disastrous flue fires arise from running a "normal"
wood fire and allowing a heavy build-up of creosote to accumulate,
then running a hotter that usual fire that ignites the accumulation
near the stove.  Then the flue fire propagates rapidly along the
creosote in the rest of the flue until the whole thing is a
self-fueled blowtorch, spewing chunks of flaming, coke-like carbon and
heating the flue red hot or (depending on the available air inflow)
hotter.

Doesn't happen with a forge flue.

If you let the flue fill with heavy coal smoke during start-up, you
can have a short-duration "event" when the smoke ignites and a
fireball flashes up the flue.  If the joints (or mortar) in the  flue
aren't tight, the overpressure during this event can blow tiny sparks
of burning soot out through any gaps.  But no sustained, self-fueled
blowtorch effect.


FWIW,
- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^