Fume hoods plans ?

[Platdigger]

Nox, shouldn't the vent at the top start out about the same size as the cabnet, and then taper as it goes up?

I mean just to make sure you have good even draft so you are not breathing anything.
Just seems to me. Not nocking your work. Other than that it looks great!
Randy

 

[jimdoc]

Here is one on Ebay for 99 cents, ending in 14 hours if anyone is near
Burke Virginia, I am 175 miles away, and with gas as high as it is and
the mileage on my truck I won't be getting it. I have seen this type at the auction I deal with, and they are nice. Don't know how it will hold up to acids, but if you get it cheap enough and your close it may be worth a try.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=150260199260&ssPageName=STRK:MEWA:IT&ih=005

 

[Mida]

I have just finished my fume hood and I will post a picture soon to inspire ideas to other members.
I have used a sliding glass panel,but I noticed it's too heavy,and I want to substitute it with something other.
Can someone suggest me some kind of transparent material I can use? It have to be resistant to the attack of nitric and chloridric acids.
Plexiglas isn't good because with the esposition to the fumes it became opaque......

 

[Mida]

Here you can see my homemade fume hood.....

 

[jimdoc]

My fume hood has a big counterweight that hangs in the back that
helps ease the window rise. It is kind of like the weights in older
windows. Maybe that would work for you somehow, and you could
keep your glass.
Jim

 

[patgspot]

Shouldn't there be an air intake to let the air flow through and pull the fumes out of the hood? It seems that that would work seeing that the fumes are heavier than air. Is this assumptiom wrong?

 

[Noxx]

You are right, NO2 fumes are heavier than air.
That's why the fume hood you saw on my lasts pictures is no more. I'm in the process of building a new one.
There will be two fume exausts, one at the top and another one at the bottom.

 

[patgspot]

I was thinking about making a hood using an old acoustic printer cover. Remember the kind for the old noisy dot-matrix printers? They have plexiglass lid with an exhaust fan built right in. I have a few of these sitting in the shop collecting dust and they've never been used (NOS). Just for temporary until I build a real one. I'm just doing my homework before I start construction on it. Don't want to have to build it twice. These covers are very large. The kind made for the wide-carriage printers. Any opinions on this?

Pat G.

 

[SilverFox]

I accidently bought exactly what I needed?

At a garagesale early this spring I bought this blower fan, WHO knew I would need exactly such a device not even 4 months later.

I plan on building a equivlent fan setup simlar to what I have already seen in the pdf files.

 

[Noxx]

I've been looking for a blower fan like that for a while on eBay but they seem to sell for top dollar... I can't grab a cheap one. Nice find

 

[LeftyTheBandit]

Would the NOx corrode the metal?

 

[qst42know]

Without a doubt, but will work for a while.

 

[Anonymous]

Noxx a good source for those squirrel cage fans is combination central heating boilers. You should be able to pick one up fairly cheaply from a scrap merchant or a local plumber from a redundant boiler.

 

[Noxx]

Thanks for the input but I just bought one from eBay a few minutes ago.

http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=360104280092

I know it's 220V but I have it in my lab...

 

[Harold_V]

Squirrel cage blowers are not a great choice for this application. They tend to build up on the vanes, eventually getting fully coated. It can actually plug off completely, or throw some of the material from one or more of the vanes, leaving the blower out of balance.

You may not experience that problem if all you're handling is slight fumes. My experience was in a hood that was used for incineration as well as chemical processing.

There are paddle wheel type blowers that resist this problem. W.W. Grainger is a source----and there may be others. I recommend them highly. I used the design for more than ten years with no problems. I can't say the same thing for the squirrel cage, which presented ongoing problems all the time it was incorporated in my first and second generation fume hoods.

Harold

 

[Noxx]

It's my second fume hood as well... But I won't incinerate in my hood so I might not experience the same problem.

 

[Harold_V]

It would be a service to readers to comment on that after you've used the blower for a few months, Noxx. That way they'd know to use, or not use one in future builds. It's entirely possible you'll achieve acceptable results----incineration liberates a fair amount of greasy smoke (incinerating polishing wastes from jewelers).

Harold

 

[Pawnbroker Bob]

I built my Plexiglass hood using a venturi effect. Been using the same squirrel fan for 15 years. I always thought this was the way it was done to eliminate the fumes from destroying the fan.

PB

 

[Harold_V]

Good design!

My hood moved roughly 1,000 CFM, with the air going directly through the blower. If you can duplicate that volume with a venturi effect, all the better.

Considering my air went through a filter before entering the fan, I don't know that you would achieve the same success, but I sure like the idea. As the filter got loaded, restriction became a problem.

Harold

 

[SilverFox]

The fan cost 2$ at my neighbors garage sale, if replacement is in order. The recovery of my losses I think will be offset by the gains of such a find.