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QUESTION:I have 2 fan units from old furnaces that I was considering using in a home
made air filtration system ( 2 boxes, if necessary ). But I'm having a
little trouble answering the first set of questions: Do I need more than
one unit? Where should I hang the unit(s)? Are bag filters really
necessary? How do you determine the maximum air flow of the unit so that
you can match it with an appropriate set of filters?
In order to answer the first question, you need to know a little bit about
my shop. I have a grand total of approximately 4320 cu. ft. of space. The
shop is laid out in an "L" shape. The long side of the L is approximately
30' x 10', and the short side is approximately 12' x 20'. The length of
the long wall is 30', and the length of the "foot" is 22'. 12' off the
long wall, and parallel to it, I have an I-beam that runs the length of the
shop. There is also a heating duct that runs parallel to it, and an 8'
long "shelf" attached to the ceiling to hold miscellaneous stuff I don't
have anywhere else to put.
The I-beam, the ductwork, and the shelf kind of separeate the two parts of
the shop. If I put in just one unit, I'm not sure that it will pull enough
from the rest of the shop. if I use 2 units, do you hang them in diagonal
corners to get the air circulating? Along the 30' wall, at one end, I have
2 lathes where I generate a lot of dust, so I thought I should have one
unit down there. On the other side of the shop, diagonally across from the
lathes, is my workbench, where I also generate a lot of dust. So one
closeby seems reasonable. And 2 units makes sense to me so that when I'm
not working in one area, I just don't turn on the unit in that area.
I've looked at the efficiency of the bag filters I can purchase locally (
none of the haeting/cooling places I've called know what one is though -
I'd have to buy one for a commercially available unit ), and they filter
out particles that are 1 micron or smaller. For the same price, I can buy
3 flat filters with the same efficiency rating. Granted, I would have to
clean them or change them more often, but is that such a big deal?
Before I start building this thing, I wanted to have the filters on hand so
I could build around them. But before I purchase filters, flat or bag, I
need to know how much air will be going through them. I looked all over
the fan units I have, and aside from model numbers, the only thing I see on
the unit are the words "3 ton Bryant". AQm I supposed to be able to
calculate air flow from that, or do I need to talk to the manufacturer to
get the air capacity?
ANSWER: I've put together a unit with a box fan and an electrostatic furnace
filter (reusable, wash it out with water). It seems to work fairly well,
and is supposed to work down to small particle sizes (not here, can't
check the blurb now). I simply bought the largest area filter I could
find (20x25" nominal) - with a furnace blower, I might use 4 or 5 of
them together, though they are obviously used in furnaces at 1 filter
per furnace blower...
If you want bags, Oneida is probably the place to get them.
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