Help with "Flume" Type Ventilation

BeadBlossoms · #1 2011-12-19, 3:27pm

I am setting up my studio in a new 10x16 ft shed and am looking for ventilation help. I am considering the "Italian" style of ventilation, which looks like a big flume type opening directly behind the torch to suck up the fumes. Or is the hood type better? I've scoured the lists and am totally confused what I should do.

I have an HVAC guy ready to do it, but he's unclear about the lampworking aspect and I don't know what to actually tell him I need

Can someone help me in plain english, lol? Thanks!!

Dale M. · #2 2011-12-19, 8:32pm

Umm... There is very little actual documentation and test results of these system... Most people comment "it works fine" with no scientific test to determine if its effective...

IF you are going to attempt this type of system, my thoughts (though untested) is use a funnel shape "collector" at torch, the larger the diameter the better, and maybe 6 inch duct and as a starting point 350-500 CFM fan.... Also be aware the rate of draw drops off exponentially the further you move away from "funnel opening"...

Dale

RSimmons · #3 2011-12-20, 7:11am

My personal opinion based on some experience is that a hood gives better fume capture than the funnel type. some people like them, I don't. Dale makes good points. whatever type of exhaust you go with, you should check it with a smoke tester to follow the air flow with you sitting in front of the torch with it running like you are working. I use these to check systems:

http://inspectusa.com/second-smoke-e...ack-p-242.html

Robert

BeadBlossoms · #4 2011-12-20, 9:06am

Hmmm, maybe it's not such a good idea then - thanks for your input.

I guess on the hood I'm having a hard time figuring out what size fan, etc to use - how do you balance it so it''s strong enough to draw the fumes, and stil not interfere with the torch flame?

cheng076 · #5 2011-12-20, 12:19pm

Third time posting this. Only trying to help and cover all the bases.

OK here we go......

1. Make a scale drawing of your room on graph paper. Put in windows and doors. Mark where your bench is going to be. Mark where you will mount the fan and hood, usually right above the bench. Mark where the kiln will be and think about how it will be supported, cart, shelf, or stand. Optional - mark where shelves, glass storage, a desk & chair might go, stereo, etc. Might try laying out the room size wise and cut little squares out of construction paper so you can lay them on the drawing and move them around for best fit (layout). I use one of those cheap, free, house drawing programs for this sort of thing. This is also a good time to select where you want to put electrical outlets around the room. I like to put them above counter height except where my desk is so I don't have cords hanging over the front edge of my bench even for temporary stuff, and I don't have to crawl under the bench to plug/unplug.

2. Room size has no bearing on vent fan size. Doing the drawing you probably already decided on a bench size even if you didn't realize it at the time. Decide what type of hood you want. There are quite a few. a. sheet metal fabricated to your design by a commercial shop. b. home made from metal flashing and wooden frame. c. wooden frame with plywood sides covered with metal or not. d. reuse of something such as a metal wash tub. e. large funnel shape usually fabricated by a commercial shop. And others. Look at the photos in the forum for ideas. Make a decision and stick to it unless it becomes impossible to impliment given other choices. It's really a balancing game.

3. Think about and decide where and how the hood will be mounted and where and how the ducting will be run. Your vent guy can be a big help here. Explain that you need to remove the gasses from your torch flame plume as if the hood was a large vacumn cleaner hose opening. Now is the time to also think about where you want to get makeup air. You mentioned wanting to have it come in at the back of your bench in front of the torch. If this is your choice then you will need to decide where the ducting will run and from where. Your idea of a flameproof box under the bench is good ( and use a screen on the opening).

4. You now have the basic mechanical items designed and selected. Now you have to select the proper fan. Given that you want to use the axial fan pictured at 750 cfm then your hood is limited to about 6 square feet. So that could be 2 ft X 3 ft or whatever combination stays about 6 sqr ft and within your budget. The hood doesn't have to cover the whole bench just the torch flame plume area of your torch.

5. At this point you have all the elements designed and selected so it's a matter of installing them and hooking it all up.

6. Think about where and how many lights you will need. Usually at least one over the bench, maybe another in the center of the ceiling, one over the desk or seating area. I like a fluorescent tube light over my torch as it allows me to see imperfections in my marbles but I like incandescents over the desk for reading and crafting otherwise I have fluorescents as general lighting...they're cheaper to operate. I use daylight tubes in them for colors.

Most people in my opinion think about ventilation backwards. The most important thing is that it function in such a manner that it supplies YOU with clean contaminate free air to breath; coincidentily but secondarily is that it remove those contaminates from your work space.

Keep at it, the light bulb will come on soon.

If I recall correctly you mentionedd your space was three sided, one end/side completely open. That will make directing makeup air into ducts under the bench impossible so in order to do that you will have to close off that open end wall and possibly add a door. Makeup air is usually passive, drawn in by the 'suction' of the vent fan. Unless the room is closed more or less air tight then your makeup will come from the open wall. It always takes the path of least resistance.