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Author: Subject: Outside Vs Fumehood
AlChemicalLife
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[*] posted on 16-7-2017 at 21:09
Outside Vs Fumehood


Hi ,
Last time i posted here was a few years ago in my young and dumb days of life .
I recently decided to start doing chemistry again as i go off to community college and than onto university, ( I want to study organic chemistry , Mining engineering and aerospace engineering )

While i wait arrival of new chemicals and glassware ( got rid of my old stuff because i thought i wouldn't ever do chemistry again and would stick to engineering and doing pyrotechnics )
I have been thinking over safety of what i want to do and whether to build a fumehood or just work outside .
It seems to me that im drawn more towards the poisonous and toxic parts of chemistry ( Anyone else think that allot of the pretty chemicals are toxic ? :P ) And i would like to do some experiments with dichromate as well as organic chemistry which involves allot of nasty solvents n' such .
So i would just like to know which would be a better idea and if you guys think working outside is a viable option or if i should just build a fumehood , The fumehood designs ive seen and thought about making seem kind scetchy , like this one https://www.youtube.com/watch?v=jggLgps-n2Y
and ive read a lot on the forum about fumehood and TBH dont understand much about it.( Im a very visual person when it comes to understanding how to build things and how things work ) im also worried to make one and screw it up wasting a bunch of money , but even worse putting my life at danger because of it.

My worries with working outside is Changing wind direction and weather . some of the experiments im looking at doing say to let somthing stir or reflux for X amount of hours or overnight , if im working outside i would be unable to do this.
Im sorry this is getting long and drug out.
Hope i posted this in the right section as this seemed like a newby type question.
Thanks for your help
~Steven
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JJay
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[*] posted on 16-7-2017 at 21:48


It really depends on what you plan on doing. I'm building mine mainly because I want to make some benzotrichloride, and it would be awfully inconvenient to pack all of the equipment I need to do that into the woods. Also, you probably already know this, but you should never under any circumstances dump chromium wastes outside.

The major problems with working outside are

a) The wind can change direction. This is not usually a problem (a campfire built inside would kill you in minutes, after all), but if you're working with toxic chemicals that don't have much smell, it's a big issue.
b) People can see what you are doing. This is not always a problem, but if you have neighbors you don't know it's not desireable. On the rare occasions when I've run into random street people when doing chemistry outside, they've been either unnaturally friendly or scared, and you probably don't want to make friends of questionable character or terrorize the locals.
c) Lack of water and power as well as other resources (tools, medical assistance, etc.).
d) Rain and other unfavorable weather conditions. Sunlight destroys some chemicals.

There are some things that you probably don't want to do inside even in a fume hood. Most aluminothermic reactions should not be carried out inside, for example.

I don't think a foil vent is the greatest of ideas mainly because aluminum foil burns easily and wouldn't stand up to corrosive gases for very long, but a foil vent could be sufficient for a lot of things and is easy to replace.

You *do* need some kind of plan for power failures.

A box fan in the window provides a lot of ventilation.




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[*] posted on 16-7-2017 at 22:14


Well in my experience you can get away with doing most stuff outside, me and a lot of the forum members do not own a fumehood.
Wile this is not something i would advise, the following video is of a guy generating SO3 without a fumehood or any proper ventilation.
https://www.youtube.com/watch?v=eNs4uN6pWM0
You are gonna have to be a little more specific with exactly what compounds you are gonna be handling as a lot of compounds and solvents such as DCM, chloroform, hexane, toluene, phenol and alcohols are perfectly fine working inside with an open door near by.
Compounds such as diethyl ether, benzene, NOx, chlorine, bromine, CO and CS2 should be handled outside or in a fumehood.
It is entirely up to as to whether you want to be handling strong acids in a ventilated place or not but conc HCl can be quite irritating if inhaled as can conc nitric acid, sulfuric acid in my opinion has never been an issue with handling it in a poorly ventilated area as i never handle particularly large quantities at a time and i never put my face anywhere near it.

Best advice would be to familiarize yourself with the properties of each compound before handling it e.g. check the flash and auto ignition points, check boiling point and vapor pressure and also check the NFPA 704 otherwise known as the fire diamond.
I would also advise researching potential health risks it can pose, e.g. does it cause liver damage or any long term health effects from exposure, does it possess short term health effects such as that of hydrogen cyanide, or is it just highly irritating or noxious.

Ideally if you really wanna be scrupulously safe you would do all your chemistry outside or in a fumehood but as time goes on and you will get more familiar and comfortable around certain chemicals and you will also start to push the limits a little more and likely fill your work space with chlorine or something to equal effect, it can also be quite inconvenient to work outside due to weather and what not.

As far as fumehoods are concerned, my advice may be substandard as i have yet to build one but generally a fumehood is as good as its extractor fan, ideally you want a fan with an external or sparkless motor to avoid starting any fires, you may also want to consider any long term damage to the inner components of the fan. a good idea might be to disassemble the fan and coat any inner surfaces that will come into contact with fumes with a chemical resistant paint such as a ptfe spray.

As for your skepticism of the quality of a home built fumehood, i can assure that it is unwarranted.
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sparkgap
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[*] posted on 16-7-2017 at 22:18


If you live in a place where you're well-separated from your neighbors, working outside could be fine, modulo the concerns raised by the other two. Otherwise, having vapors waft into your neighbors is rude at the very least.

sparky (~_~)




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[*] posted on 16-7-2017 at 22:29


It should also be noted that even if you were working in a fumehood, the fumes you will be producing are still going to likely end up at your neighbors anyway, unless you suspend the exhaust end of your hood high up in the air.
Although working in a fumehood would give you the advantage of being able to work wile its raining, which would cover up a lot of rather profuse smells such as that of diethyl ether.

Another idea may be to set up a water trap on the exhaust end of your hood to catch some water soluble vapors.
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[*] posted on 16-7-2017 at 23:42


I do most of my chemistry in a shed with no fume cupboard
if I expect significant quantities of hazardous gas to be generated then I work outside.
My main concerns working outside are basically as mentioned above;
. nosy neighbours
. 'chemical' smells reaching neighbours
. rain - not just inconvenient, potentially disastarous if cold rain drops on hot glassware

Ideally we could use gas scrubbers etc. and/or re-use any gasses produced,
but I usually allow gasses like Cl2, NOx etc. to dilute to safe levels in the breeze.

Working outdoors during winter is not at all comfortable.

I live in a fairly densely populated suburban area so neighbours are very close,
one side of my outdoor work area is the wall of my neighbour's house extension, so care is required.
The density of housing causes the wind direction in my work area to change speed and direction frequently, randomly.




CAUTION : Hobby Chemist, not Professional or even Amateur
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[*] posted on 17-7-2017 at 06:18


Sometimes I do experiments outside. A good option is to make a little barn with just 4 poles and a roof and work under that (2.5 x 2.5 m works fine). This provides perfect ventilation and prevents raindrops to get into your experimental setup.

Even cheaper and easier is a party tent. You can buy a decent one (3 x 3 m) for $50 or less.




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[*] posted on 17-7-2017 at 10:34


depends on scale but even in a fume hood i like to add scrubbers etc, i just prefer not to vent stuff into the environment. Ok my little contribution to the world wont make any difference, but it makes me feel better, and its safer.

Up till recently i worked outside, because of the weather here I hated it most the time. But anything beats working with nasty stuff inside and no protection
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AlChemicalLife
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[*] posted on 17-7-2017 at 20:41


Alright , so im gonna work outside till i build my fumehood and make sure im not gonna have stuff blowing back at me. last thing i want is NOx blowing into my face or something because i messed up with with calculating flow , or the wrong fan or just something that my luck would bring me xD .
some things that are stumping me is how to make the sash(Or more less what type of a storm window as i know nothing bout glass and what would be good for a fumehood ) , what size to make the hood ( i was thinking of copying magpies dimensions 41.5" H x 48"W x 28" D)
The baffles are also baffling me ( Pun intended ) , how wide should the gaps in the baffles be and would a thin would be suitable for them ?
I thought about making the hood from wood and than coating it in a white pain ( been looking for fire resistant pain to use ) than a coat of epoxy might also be a good idea .
ill draw up some designs on AutoCAD and post them here when im done..
Again im very sorry for these random questions....
~Steven
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[*] posted on 18-7-2017 at 00:40
A fume cupboard guide


Attachment: fumehood.pdf (322kB)
This file has been downloaded 228 times




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