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Author: Subject: Fume Hood Design, help?
FireLion3
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[*] posted on 3-7-2014 at 12:28
Fume Hood Design, help?


I've got a decent 350cfm fan and filter, and want to build a sort of fume hood/escape, but not a full out fume tent.

I am trying to base the design on something like this (picture below). It's flexible, doesn't get in the way, and very adjustable.

I just don't know how I could mount something like this such that it is adjustable. I was thinking some sort hydraulic lever/bar system to allow it to be moved around, secured, loosened.

I found some "Fume Extractor Arms", on various sites, but they all are way over priced (1000+). I can't imagine it would be too hard to build one with some zip ties attaching the ducting to a hydraulic arm or something similar.

Pic One:


Pic Two:
http://i1.ytimg.com/vi/ZF8nOW8FqNM/maxresdefault.jpg

Pic Three:
http://cdn.instructables.com/FC3/YH2M/4IDEP280HJO/FC3YH2M4ID...

Something simple along these lines. Any suggestions on how I may be able to secure something like this? I was going to take a trip to the hardware store but I don't want to be wandering around aimlessly for hours.

[Edited on 3-7-2014 by FireLion3]


Also does anyone know what APB Plastic is? My fan is alledgedly made out of this but I don't know what it stands for. The only way my current design can work is if I am pulling air through the fan first then through the filter. I'm not sure if solvents will degrade this material

[Edited on 3-7-2014 by FireLion3]
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aga
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[*] posted on 3-7-2014 at 12:54


Closest i can find is ABP-1010
http://plastics.ides.com/datasheet/e141709/kingfa-abp-1010

Only way to be sure is to drip some stuff on it and see what happens.
The only Certainty in life is that Nothing lasts forever.

The cheapest way would be to use pulleys and counterbalance weights to be able to put the nozzle where you want it, and have it just 'stay there'.

A Bit like this :
http://web.mst.edu/~leachtec/new/files/flysystemexplanation....

Maybe use 2 pulleys/counterweights so you get full 3d positioning

Some kind of clamps on the cables would be a good idea to prevent it moving due to the fan vibration.


[Edited on 3-7-2014 by aga]




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FireLion3
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[*] posted on 3-7-2014 at 13:01


Fan Vibration wont be a problem since I'll be using ducting. The fan will be on the ground. The end of the ducting that the air will be pulled through will have some kind of funnel on it. I'll probably need to find this first and then go from there. If I can move it fairly easily and "set it", then I won't need an entire hood, since I will just be able to place it right in front of wherever the fumes arise from.

If I can get that funneled end piece, then I may just be able to find a way to mount that to my tables metal-rod stand, and have it adjustable that way. Perhaps use those very thick rubber coated wires with a clamp on it to hold it up but have it be adjustable.


I just read on that datasheet that you linked above that:

Quote:
Generic Name may also be described by the following terms: Polypropilene, Polypropelene.


According to wiki this material is resistant to most chemicals, solvents, bases, and acids... so I guess that answers that question. Thanks!

[Edited on 3-7-2014 by FireLion3]
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[*] posted on 3-7-2014 at 13:08


Maybe a flexible desk lamp neck, or two or more connected together would work ?
Might even be able to find those in the garbage.
Pretty sure there were some meter or more flexible necked lamps available once upon a time.
Anglepoise ?





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[*] posted on 3-7-2014 at 13:14


With a long Ducting tube, your main worry should be what builds up in the Ducting tube itself.
Basically it'll act as an air cooled condenser, and stuff will aggregate on the walls.

The wrong things mixing in there could be Bad.
Not just tube corrosion.

There's a thread on here about that somewhere (cannot find it at the mo).
An explosion due to Krud build-up on a fume hood ducting pipe.




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FireLion3
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[*] posted on 3-7-2014 at 13:24


Excellent! That is simple genius my friend! Exactly what I was looking for. I can't imagine it would be too hard to replace the top of the lamp with a bigger funnel with the ducting attached. Lamps are cheap enough, I can pick one up at the hardware store.

You are right about build up in the ducting tube. Ducting is cheap to replace so I can do that periodically. I don't think I will be using anything that can combust in there. Maybe fumes of some solvents. At the very worst I think maybe some acid fumes or some halogens. As long as theirs no flames it should be fine. All of the things I plan to be fuming out would be are able to evaporate at room temperature (at some rate). Even some higher boiling liquids evaporate when left to stand.
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[*] posted on 3-7-2014 at 13:33


Keep the top of the lamp and take the bulb fitting out - there will be a big hole, and the reflector is pretty much funnel-shaped !

Maybe just cut the whole back off, and 'paint' the inside with silicone sealant - metals tend to be less Hardy around chem fumes.




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[*] posted on 3-7-2014 at 13:43


Quote: Originally posted by aga  
Keep the top of the lamp and take the bulb fitting out - there will be a big hole, and the reflector is pretty much funnel-shaped !

Maybe just cut the whole back off, and 'paint' the inside with silicone sealant - metals tend to be less Hardy around chem fumes.


I thought about that when I first saw it, but my only concern was that the lamp has to be big enough. I am working with 6 inch ducting and I want my funnel-opening to be at least 2x as big as any open potentially fuming reaction. For instance if I am using a small 1 liter flask with overhead stirring, that lamp in the picture would already be too small to capture all the fumes, maybe.
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DrAldehyde
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[*] posted on 3-7-2014 at 13:50


I found an CT monitor adjustable arm at a garage sale for a dollar. The guy was really glad to see it go. I haven't found a purpose for it, but I know I will. One of these might work for your purpose

download.jpg - 3kB
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[*] posted on 3-7-2014 at 13:55


Perfect !
That is made to take a ton of weight, so will stay where it's put.

Edit:

Scary image popped to mind : Seriously deadly fumes leaping madly from a 1L vessel, chemist watching closely on one side, fume extractor on the other, then power failure.

[Edited on 3-7-2014 by aga]




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FireLion3
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[*] posted on 3-7-2014 at 14:07


Quote: Originally posted by aga  
Perfect !
That is made to take a ton of weight, so will stay where it's put.

Edit:

Scary image popped to mind : Seriously deadly fumes leaping madly from a 1L vessel, chemist watching closely on one side, fume extractor on the other, then power failure.

[Edited on 3-7-2014 by aga]


The fan I use is only rated at like 100w I believe. You can use back-up power supplies that they use for PCs. I had one that was able to keep my PC with its 1100w power supply on for 30 + minutes. It would kick on instantly when there was a power disruption. So if it can survive 30 minutes with a 1100w load, then it could survive potentially 5-6 hours with a 100w load. That is more than enough time to handle a reaction and get it to settle, usually.

Luckily I won't be dare going near anything that produces "seriously deadly fumes". One day maybe, but not today.
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[*] posted on 3-7-2014 at 14:23


All sounds like Good Planning.

Not specifically Chemistry related, but Good Planning tends to Work best.

As in you survive !




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[*] posted on 19-7-2014 at 14:02


Would a 280 cfm fan be sufficient for a little hood thats 20"x20"x12" (hightxwidthxdepth)?

Right now at the moment i don´t have the money for supplies, but in the near future.
Can i cover with plastic sheeting for now?
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[*] posted on 19-7-2014 at 15:37


For something that small certainly. There are actually specific calculations for how many cfm you need on your fume hood fan but as long as you have some kind of sash you should be good!



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