divide/baffle a hood?

[yamaha200]

I acquired a whole studio of equipment. It included a table that's about 6'x2' and a hood of the same size mounted directly above. Sheet metal on the table top and around 3 sides to create a little "booth" and sheet metal for hood construction. Good start, yes? Now for the problem.

It appears to me that the fan in the hood is one of the Suncourt ones that Glasscraft sold, removed from its hood and placed in this custom made one. Looks to be 10", so its probably the DB210.

There was also a smaller Suncourt fan attached to the makeup air system. Don't know why. We're planning on ditching that and just installing large ducts from a window and routed to the front edge of the table for make up air.

Assuming the standard calculations, 2'x6'x100cfm (not sure whether to use the 100 or 125?) = 1200cfm. Wow! The existing fan is only like 300cfm for "free air" rating. Not enough.

Trying to find a single fan that powerful does not seem to be going well, and would probably cost a fortune, not to mention the noise. Installing 2 or 3 smaller fans would probably be more affordable and not so loud. But my shed is not that big so I don't really want to put 3 big holes in it.

I've seen indications that it is possible to divide a hood or add some "baffles" so that you only have to vent that section of the hood. Conveniently, the hole where the current fan is attached is near one end, so it seems that using/venting just 1/3 of the hood might be possible. This would be 2'x2'x100=400cfm, much more easily done. And if I added more torches later i could add more fans for the other sections.

Questions:
-would a 2'x2' section with the torch directly below it be large enough to really capture the flame/exhaust/etc (I've got a lynx and also a national hand torch, but would probably generally just use 1 at a time)?

-how does one go about creating such a divider/baffle? Just add a piece of sheet metal? Does it have to be just a snug fit? (seems like it should actually be sealed off). I don't have to divide the area from the table clear up to the hood do I, just the hood itself? That would make a very small working area for hands and tools otherwise.

-It seems there are some situations where its desirable to have the kiln in a vented area (fusing with shelf paper, using charcoal to create a reducing atmosphere). Trying to fit the torch and kiln into a 2'x2' area would probably not work. Would having the kiln nearby on the table be "good enough" or would this be a bad idea? My impression is that these activities with the kiln are smelly but necessarily harmful.

thanks for any advice,
laura

[Dale M.]

Originally Posted by yamaha200

I acquired a whole studio of equipment. It included a table that's about 6'x2' and a hood of the same size mounted directly above. Sheet metal on the table top and around 3 sides to create a little "booth" and sheet metal for hood construction. Good start, yes? Now for the problem.

It appears to me that the fan in the hood is one of the Suncourt ones that Glasscraft sold, removed from its hood and placed in this custom made one. Looks to be 10", so its probably the DB210.

There was also a smaller Suncourt fan attached to the makeup air system. Don't know why. We're planning on ditching that and just installing large ducts from a window and routed to the front edge of the table for make up air.

Assuming the standard calculations, 2'x6'x100cfm (not sure whether to use the 100 or 125?) = 1200cfm. Wow! The existing fan is only like 300cfm for "free air" rating. Not enough.

Trying to find a single fan that powerful does not seem to be going well, and would probably cost a fortune, not to mention the noise. Installing 2 or 3 smaller fans would probably be more affordable and not so loud. But my shed is not that big so I don't really want to put 3 big holes in it.

In most every case its probably better to use just one fan that fits needs of hood "face opening"

I've seen indications that it is possible to divide a hood or add some "baffles" so that you only have to vent that section of the hood. Conveniently, the hole where the current fan is attached is near one end, so it seems that using/venting just 1/3 of the hood might be possible. This would be 2'x2'x100=400cfm, much more easily done. And if I added more torches later i could add more fans for the other sections.

Questions:
-would a 2'x2' section with the torch directly below it be large enough to really capture the flame/exhaust/etc (I've got a lynx and also a national hand torch, but would probably generally just use 1 at a time)?

Yes a smaller section of 2 X 2 would "probably" work...

-how does one go about creating such a divider/baffle? Just add a piece of sheet metal? Does it have to be just a snug fit? (seems like it should actually be sealed off). I don't have to divide the area from the table clear up to the hood do I, just the hood itself? That would make a very small working area for hands and tools otherwise.

Yes any sheet metal partition would "probably" work, and yes it should be fairly well sealed. Foil tape uses for AC duct work should be sufficient. No the partition probably does not need to extend down to actual table top... Many studios have hoods (as opposed to a "box") with open side and the function just fine...

-It seems there are some situations where its desirable to have the kiln in a vented area (fusing with shelf paper, using charcoal to create a reducing atmosphere). Trying to fit the torch and kiln into a 2'x2' area would probably not work. Would having the kiln nearby on the table be "good enough" or would this be a bad idea? My impression is that these activities with the kiln are smelly but necessarily harmful.

thanks for any advice,
laura

Most kilns do produce a little odors at time (not much that is objectionable though) and the do produce "some" toxic gases (depending on what is in kiln) but for most part its NOT absolutely necessary to have kiln included into ventilation calculations. Having it off to the side but in close proximity to hood is usually sufficient...

Dale

[NMLinda]

If you want to try Dale's recommendation for one larger fan for your full 6' long hood, there are ways to baffle the noise so it's not so annoying. I bought a Fantech KFD10XL for my bench hood (has enclosed sides and back, like yours). This fan is about the same size you were calculating for your bench. I framed a generously-sized box around it and lined it with 2" thick foam insulation. That cut down the noise substantially. I've read that other LE members also muffle their vent pipes with things like attic insulation batting and have been happy with that, too. I haven't got that far yet, but will probably try that too.

You might be able to find a good, relatively inexpensive 1200+ cfm fan on boards like Craig's list. Folks here on LE have mentioned getting good squirrel cage fans there relatively cheap. If you ever wanted to play with more than one torch on that wonderful 6' bench of yours, you wouldn't have to worry about having to make another baffle in your hood and buying another fan for it. You may find that one bigger fan is cheaper than two smaller ones, and is certainly way easier to exhaust out of your studio than multiple fans.

Good Luck!
Linda