Construction venting system for casting

My set up for soldering so far has worked well using an industrial
vacuum cleaner for exhaust to the outside. The air cools down
through radiation in the duct system long before it reaches the
vacuum cleaner since the duration of the heating is relatively short
while soldering.

I’m seeking suggestions (preferably from firsthand experience) for
specific in-line exhaust fans/etc. to handle the higher heat and
volume of air that is generated over a longer period of time in
melting metal for ingots or a small flask.

Any guides on to how to determine the amount of air flow necessary
to do the job versus sucking all of the cool air out of the room
would also be useful. Currently the system uses 4" duct work and it
can be modified as necessary.

Thinking ahead, I’d like to be able to expand the system for an
additional station when the time comes to handle any fumes from
etching or any chemical situations needing exhaust. That may be
asking a lot for a unit that won’t rapidly corrode and at a
reasonable cost?

Thanks,
j

J Collier
Metalsmith
http://jlcollier

Look in Grainger’s (graingers.com) on the web and there
is to figure cu feet of air needed to be moved from X
area of Y height space. Then look at the high temp fans available
from their list. If the "self contained high temp fans are too small,
then look at the high temp fans plus motors to drive them. These are
usually a “squirrel cage” type fans. I made one up some years ago to
move/circulate 250-280 deg air for s special drier I built. If you
need more help e mail me off list.

John Dach