Vent and fresh air

[Deb Hopeful Journeys]

I have a question about setting up my venting system. I hope that I am not asking a question that has already been asked. I have read through most of the posts about setting up a home studio, but I want to make sure I do mine right the first time.

I will be using the recommend size steel tubing along with a work box system similar to one that I believe Bill made and showed photos on another message board. So basically I will have boxed in work space.

I am getting a squirel cage fan from Grainger. I will have a pretty short run with the vent tubing to outside. I am wondering if I run the tube straight up about 2 ft and then outside with a left elbow turn and then have a length of about 6 ft.

What I am wondering if I do the same thing with the fresh air replacement but have it with a right elbow turn and then a 6 ft run of tubing. So basically the end of each of the vents would be 12 feet apart, but the bad air and fresh air would be coming and going out the same window with a 12 ft difference pointing in the opposite directions.

I will run the fresh air under my work space with a hole in the top of my desk.

Hope this above scenario makes sense.

Thanks,
Deb in MN

[Just Nancy]

Deb,
I'm guessing in principal it would work. Covers the 2 ends being at a distance to prevent sucking bad air in as fresh air. (I think.)

Did you see the post someplace online for cold climate air return? She has flex hose that goes out and down near the ground (I think she said), covered of course to keep critters out. Then flex tubing to come in and near the torch. Helping insure the new cold make up air is pulled out of the room, not the room temperature air.

I'm doing something similar with pvc from the loft above my bench.

Good luck

[Dale M.]

I believe the requirement is the exhaust and the fresh air intake must be 10 feet apart. The is no specifics on how that is accomplished... Being that the exhaust air will be warm and should rise and fresh air intake is from cooler outside air (down low) I think you may be good...

IF you are going to bring makeup air in same "portal" as you use for exhaust, YES! Why not bring makeup air in under bench and bring it up between torch and back of bench and that way the cooler air does not have to circulate into room....

http://www.artglassanswers.com/forum/viewtopic.php?t=150

Dale

[Deb Hopeful Journeys]

I thought it might work. I am so glad that I have been studying and thinking what the best way would be. I will post photos when I have it completed!!!

Thanks Dale for all your info you input here!!

One last thing. Does the venting tube run of 10 ft affect the strength of the cfm I need. I have done the calculations according to the box/workstation I am building and realize what I need for cfm for that. I just wasn't sure if the tubing length affected that or not.

Thanks!

Deb in Freezing MN

[Dale M.]

Well with 12 feet of ducting outside and various twists and turns, yes there will be static pressure issues. You need to work through some calculations as to how much static pressure (flow loss) all the ducting will cause, consider duct diameters and work with some various fan specifications to get proper air flow...

For every turn and twist and straight length of duct between face of fume hood and exhaust end, there will probably be equal restriction on air intake so you really need to figure total length and total number of turns (static pressure losses) for complete length of ducting (as if there were no hood in middle)...

Dale

[Deb Hopeful Journeys]

So Dale, how do I calculate that. Is there a thread, information posted somewhere?

Thanks,
Deb in MN

[MikeAurelius]

You can find the information on the Art Glass Forum, Deb. I believe it's in the technical Documents section in the Library.

I would not use 6" ducts -- 8" free flow provides 350 CFM of fresh air. Depending on your fan size, you may need 10" or larger yet.