igor wrote:

On Mon, 26 Jul 2004 20:38:12 -0400, Jonathan Oman
wrote:

Okay, I did a google, but did not find the answer. For a dust collection
system, where should the blast gates be placed for each machine drop? Six
inches from each machine, or just past the 'Y' coming from the main line?
Does it matter?

FWIW -- I need to put a damper in my HVAC system, in the main trunk supply
that runs from the basement air handler/furnace up to the attic. There
are
two "main" trunks - one for down stairs one for upstairs. I asked my HVAC
guy whether I should make a point of putting the damper as close to the
plenum at the air handler and he said it did not matter much.

Now, with the recent debate here over air flow there may be a
scientifically "correct" answer to your question. However, it would seem
that if (theoretically) the blast gates and each hose section were air
tight that it would not matter where a gate went. That being said,
whether the real world fact that there will be some leaks makes a
difference, I dunno. -- Igor.

PS: This being said, my first instinct is/was that Gene is right. I know
it is often said that one is supposed to take that first instinct on SAT
test questions, but it may not be true of DC system design.

Big question--how powerful is the dust collector and how strong are the
ducts? All ducting between the blast gate and the dust collector needs to
be sturdy enough to not collapse when all the blast gates are closed with
the power on. If you're using a shop-vac it's not that much of an
issue--if you're using a 5 HP cyclone then it's another story.

There's also a convenience issue--you need to have the blast gate close
enough to the position where the machine operator normally stands that he
can operate it without undue strain or contortions or reaching through a
"danger zone".



--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)