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Author: Subject: Questions about Fume Hoods and Filtering Exhaust
evercurious
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[*] posted on 4-2-2010 at 14:08


Quote: Originally posted by Magpie  
Quote: Originally posted by evercurious  
@ Magpie
1. Your Grainger blower, can it handle HCl fumes without being damaged?
2. The exhaust area for that blower is a rectangular shape - where did you find rectangular shaped PVC piping? I've only ever seen circular ones (forgive me if this seems like a silly question - maybe it can be purchased from pluming supply stores?)


1. The blower internals are epoxy coated. Whatever HCl fumes I generate are minimal and are diluted with 450 cubic feet per minute of air. I haven't inspected the internals of my blower in 5 years, but it seems to be working fine. I only occaisionally use HCl - my hobby is chemistry, not metal dissolving.

2. All those blowers have rectangular outlets. I had a metal fabricator make a transition piece out of stainless steel. Yes, it was expensive.


Regarding your second point - I'm having a difficult time figuring out how to construct a simple fumehood without spending a fortune on custom parts. Any suggestions as to a type of blower or fan that would work adequately for what I want - without having to get a custom made part? Is it possible to find square shaped PVC piping that I could use instead - or is a transition piece really needed?
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Magpie
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[*] posted on 4-2-2010 at 18:50


Quote: Originally posted by evercurious  


... I'm having a difficult time figuring out how to construct a simple fumehood without spending a fortune on custom parts.

Any suggestions as to a type of blower or fan that would work adequately for what I want - without having to get a custom made part?

Is it possible to find square shaped PVC piping that I could use instead - or is a transition piece really needed?


> What's so simple about a fumehood? If they were simple vendors would not be able to sell them for upwards of $10,000.

>You can build it right, or you can throw something together. I'm the wrong guy to ask for the latter.

>I'm not aware of rectangular PVC ducting.




The single most important condition for a successful synthesis is good mixing - Nicodem
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watson.fawkes
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[*] posted on 4-2-2010 at 19:31


Quote: Originally posted by evercurious  
Regarding your second point - I'm having a difficult time figuring out how to construct a simple fumehood without spending a fortune on custom parts [...] Is it possible to find square shaped PVC piping that I could use instead - or is a transition piece really needed?
It's either time or money, so you're voting for time. I hope your workshop is moderately well equipped, because you're voting to make the requisite parts yourself. If you don't want to use stainless for materials costs, you could use PVC sheet; contact a supplier to plastics fabricators in a yellow pages.

I've seen centrifugal blowers with round output ports; they're all made from cast plastic. I seem to recall they're more money that the ones from metal for equivalent size, and I've never seen them particularly large. Perhaps you'll have better luck than me in locating one.
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evercurious
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[*] posted on 4-2-2010 at 20:21


So everyone on here who has built themselves a fume hood has had a custom-made transition piece built for their blower? I guess I'm just wondering what the alternatives are. What did you use watson?
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watson.fawkes
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[*] posted on 4-2-2010 at 20:41


Quote: Originally posted by evercurious  
So everyone on here who has built themselves a fume hood has had a custom-made transition piece built for their blower? I guess I'm just wondering what the alternatives are. What did you use watson?
I do my own fabrication. My shop, not in a residential space, is moderately well equipped.

You can buy transitions off the shelf in galvanized sheet metal (zinc coated mild steel). For light duty, they'll work OK. Corrosives will eat them. If you're dealing with corrosives, you need adequate materials. I don't know how much HCl you're planning on removing, whether it's wet or dry, or what temperature it is, so I really don't know what level of protection against corrosion would be adequate for your situation. It's possible that a powder-coated or epoxy-coated standard transition would do fine for you. What I can say, is that if you need heroic measures, it's possibly something not to do in your basement.
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[*] posted on 6-2-2010 at 14:14


From my understanding H2S & Thiols can be oxidised to be a little less noxious using hypochlorite solution, amines can be absorbed into acid, acids into base and ammonia into water/dilute acid. The problems that still occur are mainly to do with solvents, most of which will be absorbed into activated charcoal. I've heard/read that various other strategies can be/are being used, but this would neutralize most of the more noxious fumes from home chemistry. Of course, brushless motors in anything that is going to be exposed to flammable vapors is a good idea.

PS In the past I've generally utilized the fact that I resided in a low-density/rural area, and only had to neutralize the MOST noxious/dangerous fumes, the rest could be allowed to run free. Now I am in a suburban setting and I too will have to look at neutralizing/deodorizing the outflow from my experiments.

[Edited on 6-2-2010 by un0me2]
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evercurious
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[*] posted on 8-2-2010 at 09:56


What about the materials I should use to line the hood with - I have read about people using wood then just covering it with a layer of epoxy resin. Would that be adequate, or would seeing if I can get some polypropylene and coating that with epoxy be a better idea? The wood would definitely be easier...
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