Tuff Shed Studio

[Mary K]

At last the maddess begins! My tuff shed will go up August 1. It is the 10 by 12 tall ranch building.
It will have a sash door ( window that opens in door ) and a large window in one of the long walls.
We are mulling over the issues with the ventilation system, & my DH has come up with a design to have a hood made that will measure 30 by 30 inches square and 24 inches high, tapering to the top of 10 inches with an 8 inch round opening for pipe. The pipe will have one 90degree turn and go out the top as close to the ceiling as possible under the eves. The hood will be flush to the wall on the backside of the hood. The workbench will be 36 inches deep, running the width of the interior. This should put the torch in about the right position for the hood, ( we hope ). We plan to put two 8 inch sceened openings in the workspace in front of the torch vented to the outside, at least 10 ft away from exhaust, for fresh air. Also I have the door that I can open the window in for more air.
Does this sound like a good plan so far? We are looking at fan types and sizes. We are thinking around 745cfm or more? Is it important to have a fan that has speed control? (I'm a control freak, so I think it is.)
Any suggestions on where to get a fan, what kind, etc???
I'm excited, oh... but I want it to be done right, so it will be safe!
Any input is appreciated!
Thanks!
Mary K

[Diane (clarus)]

Mary - this sounds like a great setup. Is the hood going to have sides, and how far above the bench will the opening be? 745 CFM and 8" duct sounds fine. I have a 747 CFM fan and have a hood opening that's just over 6 square feet (see my setup in the studio section under "My Studio" - I think its still on the first page). My fan is one that's designed for use in a hydroponics setup, but is a solid metal housing and blades; it's rated for 140 degrees F and it's never gotten anywhere near that with my Bobcat. I don't have a speed control, but don't have any trouble with too much suction so I don't feel the need for one - I'm VERY happy with my setup. Others recommend using a squirrel cage blower from Grainger, but with my setup that wasn't going to work.

I look forward to seeing your studio when it's done!

-Diane

[Mary K]

Thanks Diane-
We were not thinking of putting sides, unless it needs them. According to everything I've read, 24 to 30 inches above the bench? Which is best? We have looked at a lot of fans from Granger, most say 104 degree is all they will take. I know it must be hotter than that. My fan will likely be just outside,in a housing we will build. Also my fan will be closer than yours to the torch.So I think that will make the exaust hotter?
And on it goes. Now the floor. I had thought tile, but Tuff shed says don't use tile, it will warp the floor. Not gonna have a bare wood floor with hot flyin' glass.( I do soft glass as well as boro)
The fan is the next thing we have to decide on and get, can't do the electrical until we know what we have to wire.
Mary K

[Dale M.]

Actually 754 is a little lean...

30x30=900sqin

900/144=6.25 sqft

625x125=791.25 cfm.

Considering a few feet of duct and at least one turn... Plus length in inlet ducting, you probably need a little bit bigger blower than 745 cfm. 800+ cfm would be better.

Dale

[Mary K]

Hey thanks Dale-
Can you get too big a fan? What would be the upper limit? Is 24 inches the optimum height for face of hood?
Thanks

Mary K

[Diane (clarus)]

Mary - if my fan was much stronger I would be concerned about it sucking up stuff from my bench. As it is, it seems to be working well based on my smoke test and the fact that I can torch for hours, even using silver glass, and not feel any effects of the fumes. I was able to do 5 hours in one stretch one evening (a luxury that I wish I had more often!) and I was fine. My hood is 24" above the top of the bench and even though I have my chair sitting on the high side and I'm tall, I don't bump my head against the edge. There are lots of fans out there - if you wanted to get one based on Dale's calculations, the one I have comes in a 10" version that is 790 CFM.

Here are some other links to information about calculating fan size, how ventilation works, etc.:

http://www.artglassforum.com/forums/showthread.php?t=1915
http://www.artglassforum.com/forums/showthread.php?t=1918
http://www.artglassanswers.com/forum/viewforum.php?f=12&sid=823ac367d0ecca59d5741ff525d0efb0

Keep us posted and remember that there are no stupid questions.

-Diane