Fume hoods plans ?

[ddrew]

Greetings all,

I have added to a thread in the Safety Forum that I've been working with other members on a Fume Hood design. I just found this thread so I thought I'd link that other discussion and see if I can get any other ideas or input on my design. That thread is http://goldrefiningforum.com/phpBB3/viewtopic.php?p=15376#15376.

To summarize my design, I'm building a plywood cage (36" wide x 18" deep x 36" tall) with tempered plate glass sliding doors, and using a Telfon film applied to the inside surface. I found a 'Negative Air Machine' that produces 550 cfm of air suction through two prefilters and a cylindrical HEPA filter, and vents outside the hood. This machine is about the size of a rolling shop vac, and would have attach with an intake port on the bottom rear of the hood. I'm looking at using a refillable Carbon Prefilter (http://tinyurl.com/243jpq) that uses activated carbon and potassium permanganate as the filter media (http://tinyurl.com/yrusts) - see attached file for more info on this. I would use a pleated 1st stage prefilter to capture any airborne PM's.

I was curious if anyone has any concerns about using this type of pre-filtration media with the various chemicals and fumes produced during refining processes described on this site. If a better pre-filtration media is suggested, please let me know and I'll be glad to consider it.

I also had questions about the make up air, and was undecided about bringing in fresh outside air, or simply recycling the exhaust air from the Negative Air Machine?

In regards to these Negative Air Machines, they are used in the asbestos abatement and carpet cleaning industries, and are found on craigslist or ebay quite frequently. The unit I found is a Dri-eaz DefendAir XL, but I was also looking at a CRSI 2000 (http://tinyurl.com/ys3bem) which is a much heavier duty unit. It has a exhaust capacity of 2,000 cfm, but is much heavier weight which would double it's cost in shipping weight (units are selling for $2-300 and freight is in that range too). I bought this DefendAir XL from a local carpet cleaning contractor that used to do mold abatement, and got this unit for $175 with local pickup. The difficulty is these HEPA filters are as expensive as the units, and that's why I want to capture as much in pre-filtration before going into the HEPA filter.

I haven't purchased the pre-filtration filters yet, and would greatly appreciate any ideas, suggestions or other thoughts from the more senior 'forum fellows' that have worked with this topic. I'll be glad to make working drawings as soon as I get the design complete, and provide a copy to the forum library.

Thanks in advance for all input regarding this design.

Edited to try and fix URLs and attach file

 

[Palladium]

http://www.usplastic.com/catalog/product.asp?catalog%5Fname=USPlastic&category%5Fname=56&product%5Fid=14576

 

[ddrew]

http://www.usplastic.com/catalog/product.asp?catalog%5Fname=USPlastic&category%5Fname=56&product%5Fid=14576

Thanks Palladium, I appreciate the link. Any other comments on my fume hood ventilation plans? Have a great weekend, everyone!!

 

[ddrew]

Bump . . .

Buehler?? Anyone??

 

[banjags]

For a blower assembly... Would a blower and the box from a vehicle work... They move a lot of air and should be relatively easy to mount and adapt to a "custom" built fume hood.

 

[grainsofgold]

I tried constructing a fume hood like the diagram in the Hoke book . but I mounted the blower unit too high above where the fumes were being made and it did not produce enough of a draft to carry the fumes out.

I was thinking about this recently and thought if you were to connect a blower via a step down connection into a small diameter pipe say 1/2 inch in diameter that is 2-3 feet long before it connects to a Y fitting - wouldn't this create a greater CFM and force the fumes up quicker to the outside vent? and of course bring the blower and the Y closer to the source of the fumes-

Art

 

[Lou]

It's all about the face velocity .

Keep in mind that improvising your own fume hood will probably make your work safer, but it won't make it anymore approved as it probably won't be code compliant.

 

[goldsilverpro]

If I remember right, you need about 100 cfm per square foot of opening.

 

[Anonymous]

Noxx:

I noticed your in Quebec so I thought I'd mention that the federal government often has equipment like fume hoods up for auction by sealed bid. (I understand they also have "Cash and Carry" sales too). When I was in Calgary several years ago, I checked out some of the auction items, including several fume hoods that they had at the time and while I didn't buy one, I did find out that they sold for under $10.00 each. They were about 6' tall by 5' wide and about 2' deep, with clear strips of some type of rubbery material in front, but I'd prefer plexiglass/lexan folding doors instead.

Check out the website here:
http://crownassets.pwgsc.gc.ca/main-e.cfm?sidenavcmd=contact
(If your close enough, the Ontario location might have more selection.)

I recall some of the other scientific equipment, (professional microscopes, centrifuges, etc), and more industrial/mining related equipment they had, (on and off road wheeled and tracked vehicles and assorted machinery), that sold dirt cheap. Might be worth while checking out?


OGG.

 

[Noxx]

I will take a look, thanks.

 

[Anonymous]

the Y is sewer clean out it can be purchased at any HOME DEPOT, it produces a draft based on Bernoullis (spelling) research in the 1600's. It part of his work that describes low pressure lift or drafts (the theory of lift on an airplane wing).

 

[Oz]

Brav01,

That is the route I plan on taking as it does not involve the blower assembly being acid/fume resistant. It is very similar to the venturi effect.

 

[grainsofgold]

http://www.research.northwestern.edu/ors/labsafe/hoods/index.htm#Conventional%20hood


I found some good fume hood information and wanted to share it-


Grains of gold

 

[jimdoc]

Here is an Ebay link if anyone is in NY it may be worth checking out;
http://cgi.ebay.com/LABORATORY-FUME-HOODS-LOT-OF-4_W0QQitemZ330236580038QQihZ014QQcategoryZ26237QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[Noxx]

Guys,
I'm currently building my own, I should be able to post pics within a few days.

Stay Tuned !

 

[Oz]

That’s great Noxx, I look forward to hearing what materials you chose and seeing your method of construction. This is something I need to do soon as well. It sounds as though you are beyond the planning stage but I have been thinking of using slate for mine, at least for the base and sides. Does anyone have any knowledge as to the suitability of this material?

 

[Shecker]

It was once suggested to me to run the fumes through a wet/dry vacuum cleaner containing a pool of water with a reducing agent. This was suggested for recovering Os and Ru from hot AR and running it into a solution of ammonium chloride.

Randy in Gunnison

 

[Noxx]

Alright, here are three pics guys:

First one, my hood and a table.

[IMG:1024:768]http://i29.tinypic.com/2ps4tw2.jpg[/img]

Second one, close-up look at the hood. You can't clearly see it but the front panel is there. I went the cheap way and I bought an acrylic panel which is 0.08'' thick for 15 buck. I could have buy a lexan panel which is 1/4 thick for 70$ lol

[IMG:1024:768]http://i25.tinypic.com/2qtwbci.jpg[/img]

[IMG:1024:768]http://i29.tinypic.com/1q3kp0.jpg[/img]

Cutting though acrylic (of this thickness) is a real pain in the ***. It breaks very easily. I used my dremel with a pointed tip (the one with diamonds) and it works very well.

The hood and my lab are still in an early stage, I will post pics of the progress.

 

[SapunovDmitry]

Everything looks great Noxx.
The only thing i wouldn't do is making a plug deep inside. I have mine on the right panel near the exit. Cause when you try to turn it off (if it's very urgent) you have to be able to reach it not having your hands inside.
But though it's reeeeally nice.
Good job Noxx.

 

[Noxx]

Well this cabinet already had a hole in the center so I decided to put the plug there. I think I'll add a breaker at the opposite wall to shut off the entire current if needed.

Thanks for the comment.