Sciencemadness Discussion Board

Fume Hood for Urban Apartment

beerwiz - 27-4-2018 at 09:36

Almost all chemical fume hoods are large and heavy and can't even fit through the door of an apartment not to mention making turns when moving it from room to room. They are too large and bulky for the typical urban apartment. They also don't make disassemblable models.

How can one deal with fumes in an urban apartment?

Another issue is the venting outdoors, you can't make a hole through the wall or roof, so what other option is there other than through the window? One would prefer a discreet venting method? What are some discreet methods of venting outdoors?

If you are the entrepreneurial type, I think there's a good market for disassemblable fume hoods, it's much easier to transport it and install in pieces in tight spaces than in one or two whole heavy pieces.

Ubya - 27-4-2018 at 11:37

you can build a a small fume hood without much effort, the problem is that in a small fume hood you can't work properly, i mean, a condenser can be 60cm long, but if you use a standard 30cm condenser, your fumehood must already be at least 60cm to allow flasks and heater. i also live in an apartment and this brings many challanges, i'm "lucky" because i live on the last floor and my home is the only one on this floor, so i have a really small space before the door where i put my homemade fumehood.
venting outdoors is the only option, otherwise it wouldn't be a fumehood:D
if a window isn't close to where you want to locate your fumehood you'll need to use a flexible tube like this and a stronger fan to compensate air friction of the tube

Bert - 27-4-2018 at 13:33

If you look at a typical vent stack for a natural gas burning water heater, or a natural draft combustion heating furnace, you will note a "flapper" in the line, just above the appliance. It's there to reduce the suction from the chimney on the combustion chamber, allowing the combustion gasses a longer dwell time where they are doing there work.

If It's colder outside than inside, that stack is trying to pull in air, through the flapper and they have left you a handy place to attach your fume extraction duct over this mechanism after propping the flapper open. I have done this in an apartment building where I had access.

Obvilusly, extremely corrosive or highly flammable fumes with a low minimum explosive % in air are a BAD IDEA here. Or perchloric acid fumes, that kills the chimney sweep in an unexpected explosion.

Sulaiman - 27-4-2018 at 14:04

In my opinion,
if you live in an apartment your first consideration should be not making toxic/obnoxious/suspicious fumes.
This means that for each experiment you should use suitable scrubbers.

I have read of venting fumes down past the S-bend of a toilet,
and a colleague who only has occasional use of the family bathroom as a lab
used the s-bend of his bath for NOx fumes
- but that may cause corrosion problems.

Reboot - 27-4-2018 at 14:56

Quote: Originally posted by Sulaiman  
I have read of venting fumes down past the S-bend of a toilet,
and a colleague who only has occasional use of the family bathroom as a lab
used the s-bend of his bath for NOx fumes
- but that may cause corrosion problems.


That's...kind of brilliant. :-) Buildings have vents on the sewer lines (venting to a small chimney-like structure on the roof.) It won't handle high air flows, however, and if you put a lot of pressure on the line you may end up forcing contaminated air out other people's drains. All things considered, I wouldn't recommend it.

For small volumes of air/gas, I would probably set up a tub of water with a pump driving a venturi aspirator. Water will absorb a lot of things, and you could spike it with something appropriate as a scrubber in many cases. (For instance, a bit of acid to absorb ammonia/amines, or carbonate to neutralize acids.)

I've started working on a ductless fume hood (using activated carbon and other scrubbers to remove chemicals from the air), but it's not an insignificant undertaking and it comes with some potential risks compared to a traditional ducted hood. If you just want to control smells, I would start with a blower and activated carbon filter of the sort used by pot growers.

More broadly, I don't think you should be doing anything that requires a hood in an apartment. Too many things can go wrong.

zed - 27-4-2018 at 16:08

Well, you could introduce a connection into your "Soil" pipe system. At least, in the U.S. you could.

The soil pipe already vents Methane Gas, generated in the local sewers.

It's about a 5 inch diameter pipe.

Were a "squirrel cage" blower introduced into the system, it might be able to produce a considerable updraft.

Needless to say, problems could arise. Serious problems.

Your fireplace or furnace venting might be used. Once again, problems could arise.

An open window, properly built around, can do the job nicely. I have seen this done well. And, there are some examples either here, or on Youtube.

Doug's Lab has a set up that isn't bad. https://www.youtube.com/watch?v=YyUW5J-Kt5c



[Edited on 28-4-2018 by zed]

[Edited on 28-4-2018 by zed]

[Edited on 28-4-2018 by zed]

beerwiz - 27-4-2018 at 19:15

1. The most practical stealth venting solution seems to be a window vent kit like that for a portable air conditioner, only well sealed after installation.

2. For the fume hood, I think it's best to DIY with wood and cover it with an inert coating.

3. The only thing I can't figure out is the SASH system (the acryllic window that goes up and down). More speicifically a hardware system whether it be railing or else so it goes up and down vertically and stays in position.

Anyone know of a suitable vertical railing/hardware system for the sash?


Ubya - 28-4-2018 at 00:34

Quote: Originally posted by beerwiz  


3. The only thing I can't figure out is the SASH system (the acryllic window that goes up and down). More speicifically a hardware system whether it be railing or else so it goes up and down vertically and stays in position.

Anyone know of a suitable vertical railing/hardware system for the sash?



i'm building my fumehood from 0 and the last thing i need to build is the sash. i thought of using just friction, sandwiching 2 o 3cm of the acrylic or glass pane sides between a frame of wood loose enough that it will move freely, and then sticking to the wooden frame (between glass and frame) a kind of rubbery sponge i saw used in windows to make the necessary friction to keep the weight of the glass pane but not so tight that i can't move the window up or down. this might work or not, if it's not working i will use bolts in the upper part of the frame to press on the glass when i want it still, and when i want to adjust the height the plan is loosing the bolts, moving the window and then tighting them again.

Reboot - 28-4-2018 at 09:25

If you don't mind the look, it's hard to argue with the practicality of using a cheap pre-built vinyl window. If you want to entirely build your own, the usual solution used by window manufacturers (and fume hood manufacturers) is to use springs or pulleys with ropes and counterweights in order to neutralize the weight of the sash. At that point it doesn't take much friction between sash and frame to keep it at the height you leave it at.

VSEPR_VOID - 28-4-2018 at 23:10

Quote: Originally posted by Sulaiman  


I have read of venting fumes down past the S-bend of a toilet,
and a colleague who only has occasional use of the family bathroom as a lab
used the s-bend of his bath for NOx fumes
- but that may cause corrosion problems.


That is a very creative idea! I think that if it did cause any corrosion that would be the land lords problem.

"What? I have no idea why the pipe has a whole in it."

Alternatively you could just add a scrubber for very corrosive fumes but I dont think it would be an issue. I would be worried about toxic gasses (HCN, or something similar) building up in the pipes of the building, but I imagine such pluming was designed to handle the build up of toxic gasses if it was designed to remove human waste.

Magpie - 29-4-2018 at 09:58

https://www.sciencemadness.org/whisper/viewthread.php?tid=70...

VSEPR_VOID - 29-4-2018 at 13:38

If I were you I would test your "toilet-sink hood" with dry ice before doing anything dangerous.