thunderfvck
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Ventilation
My lab is currently set up in my basement. It's in one of the rooms which isn't very convenient, most of my stuff is on a round table. This
is very sad, very poor, so I'm going to move it over a room which is filled with shelves and such. Ideal. Only problem is there is NO ventilation
in there. The closest thing I'll get to ventilation is opening the door and running some fans.
If any poinsonous gases are produced, my only means of survival are aborting through the door. Assuming a fan, or multiple fans are kept running, and
the door is wide open, will the gasses dissipate enough to be harmless? The closest opening is my open door up the stairs. You see, I go down into the
basement via the stairs (facing the stairs is a door) and at the bottom directly to my left is this room. So, what should I do in the worst case
scenerio?
Someone is going to come in due time to do some work on the house, he will be asked if anything can be done for ventilation. In the mean time I want
to know what you all think on this issue.
Thanks!
[Edited on 12-3-2004 by thunderfvck]
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Organikum
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- get a gasmask
- if in doubt, run.
Without ANY ventilation is not to do as solvent fumes etc. also accumulate soon and will give you serious health problems fast.
Try fans and check how they work by a cigarette or similar smoke producer - thats easy and shows fast if fresh air comes in/fumes are vented out. A
flexible aluminium airduct might be a possible solution - a bilge fan is best and not too expensive - these devices are explosion proof thats an big
advantage of course.
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Turel
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Most heartily agreed
Working with zero ventillatilation is a serious, and more importantly, and immediate health risk for you and others. I know you are aware of this
thunderfvck, so please don't think I'm lecturing you, I'm not. It is just that other less informed individuals read these threads as
well.
Whatever measures you need to go to to produce adequate ventilation, do it. If it costs money, spend it. You don't need the most expensive air
setup money can buy, just something to adequately remove toxic and flammable fumes and supply fresh clean air.
Check out Home Depot or the like, and look around for flexible dryer tubing. It is used to ventilate hot air from a clothes dryer, and is very
flexible, and modular. if you had enough length of this for example, you could seal them together (excessive duct tape would even work fine) and run
the line outside the house.
On the end on the inside, enlargen the opening with something, say a cardboard box frame holding the shape open of a trash bag, giving you a large
inlet. Personally I would put the fan on the outside end, fixated to the exit opening, drawing air out of the line, and letting the vacuum created
draw more air inside from your room. If using something stiff like cardboard to hold an opening wide, taper the width down as it gets closer to the
duct. Do not leave it as a true box with a hole in it. This will create a good deal of turbulance if your fan is strong enough, and circulate just as
much gas as it removes. A tapering width will reduce this turbulance, and is an easy fix.
You can leave the doors to this room and to the basement open, correct? I would recommend doing so, as you will obviously need a supply of fresh air.
Use a stepless fan (one without commutators) to lessen chance of explosion.
There are three main classes of nasties you would be working with, and try to inhibit:
Flammable/explosive chemical fumes from solvents and reactions. These will be aptly removed by a simple ducted fan setup.
Noxious gases/vapors will either be easily detected by your nose and eyes and lungs, or by an independent chemical test sampling you will set up,
because you are a good man and think ahead, right? For example, you happen to know that the reaction you are doing can produce HN3 as a side effect.
Now whether this gas is considered noxious or insidious is up to you. I am probablyone of the few who has actually had HN3 poisoning before and been
rushed to emergency room. I consider it noxious. Pain like I have never felt before. I have had both hydrazine poisoning (a few times) and have known
people with NO2 poisoning (Iwork with these every day, so don't think I'm a wacko exposing myself to all this on purpose, but the HN3 was my
fault, not work.) HN3 does not creep up on you like NO2 or N2H4. One minute you are fine, and the next instant you feel burning in your lungs a lot
like fiberglass, and an extreme shortness of breath. The effects get far worse from there, quickly. But the effects are immediate.
For something like this, you would never do a reaction that might produce HN3 in an open container vented into the room. It should be in a sealed
environment, with exhaust gases piped into NaOH solution. For a possible test for excess HN3, you would have an enclosure around the entire appratus,
with the only exit venting into a solution of transition metal acetate, and watch for precipitate. This is not ideal, but not everyone has access to
HN3 detectors, seeing deposition of metal azide would be your que to remove power and get out. This illustrates a good safety practice that can be
employed for just about everything. If you know what gases can be produced, create traps that give visual indication of their presence, to warn you
before you do not feel good.
The third type are what are called insidious poisons, which means they can kill you before you know something is wrong. These are by far the most
dangerous. Cyanide gas would be a great example. It is said that only 1 in 8 people can detect the smell of cyanide at the lowest concentration
required to kill, so although it is possible to detect the smell, I don't think anyone should count on this as their prime method of defense.
Unfortunately, their is no special countertactic available to match their special added dangers. One can only apply a mix of paranoia with the
measures indicated above. If you are the constructive type, consider creating a fume hood, or even better, a large glovebox if you have the time. Make
it a side project that you work on a little at a time, not some big obligation that can become tiresome quickly.
I too work in the basement, but by choice, not by circumstnce. My laundry room is in the basement, and I use the air ventilation duct as the exhaust
exit for my little homemade fume hood, because the ducting leads right outside into the back yard where everything is dead anyway.
Good luck, and inform us if anything proposed is unfeasable, or any special circumstances need to be accounted for.
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I am a fish
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| Quote: | Originally posted by Organikum
...check how they work by a cigarette or similar smoke producer... |
Smoke generators for testing ventilation are available commercially. Make sure to use one suitable for the volume of your basement, otherwise you
could completely flood it with smoke.
1f `/0u (4|\\| |234d 7|-|15, `/0u |234||`/ |\\|33d 70 937 0u7 /\\/\\0|23.
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axehandle
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Ok, that decides it. I'm going to buy a gas mask. The military kind. They only cost about $50...
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unionised
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A lot of vapours that are toxic by inhalation are also toxic by skin absorbtion.
You really need ventilation (and that's before you look at the fire hazard)
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vulture
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thunderfvck, I noticed you recently acquired a vacuum pump.
If not in use for experiments, it could be used to suck noxious fumes out of your lab. These things have been designed to run continously.
An improvised hood connected to your pump could do wonders.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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axehandle
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| Quote: |
A lot of vapours that are toxic by inhalation are also toxic by skin absorbtion.
You really need ventilation (and that's before you look at the fire hazard)
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I know. I was more thinking of simple things such as hot SO3/NO2 vapors. Better a disfigured arm than a disfigured face, eh?
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thunderfvck
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This appears to be quite a bit of work.
So I have decided to retain the location I am situated in and just bring a desk in, with some shelves and such. I have a window directly above me, so
I can easily open it, get a fume hood going maybe, vent the fumes outside, oh yeah. Now I don't have to go about tearing holes into walls, AS
MUCH FUN AS THAT WOULD BE. My mom would not be pleased.
In responce to Turel, surely there must be a website or something of the sort that outlines all the visual warnings that one could prepare before
running a potentially harmful reaction? If not, there should be.
There should be a Precautionary Measures forum on this website, or something of that nature...
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axehandle
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The real challenge lies in the choice of materials for the exhaust fan, and its blades. They must be able to take *anything*. I'm at a loss right
now, I'm having the same problem. The best thing I can come up with is aluminum blades, since Al is resistant to most things... but how to
insulate the electrical motor?
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BromicAcid
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| Quote: |
There should be a Precautionary Measures forum on this website, or something of that nature...
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Most people get upset when you tell them to be careful of a given chemical because they are already firmilar with it. If we had a precautionary
measures area it might cause some to endevor to put up everything they could think of and eventually it would just be an MSDS depository. Just
don't go mixing things indescriminately and look up compounds you will be making, MSDS's are availbe freely on the internet, you might also
own something like Hawley's Condensed Chemical Dictionary for a quick reference source.
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Magpie
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materials for fan and ducting
For materials of construction for a general purpose venting system I would recommend inquiring into what commercial grade chemical fume hoods use such
as you find in a Fisher catalog, i.e., Labconco, etc. I've noticed that the only time they seem to call out a special hood is for use of
perchloric acid. I'd be surprised if it wasn't Stainless Steel 316.
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Turel
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Motor Isolation
axehandle,
Motor isolation is accomplished reltively easily by simply constructing a centrifugal fan. This places the motor beyond the functioning appparatus,
and not exposed to the flow in any manner. A centrifugal fan is very simply to make, and will create quite an airflow. Use an electric motor from an
old washer or dryer for example. Fashion the blades and backplane from stainless steel sheet metal, and you are done. I have a book on this if anyone
is interested, I can get it scanned.
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axehandle
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I have a centrifugal fan that's used in my propane burner. It seems to work like you described. So I guess I could just copy its design,
replacing certain parts with stainless. Although I'd prefer Al... The fan is extremely silent, yet very powerful.
Thanks.
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Magpie
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fan material
First of all I agree with Turel that motor isolation should not be an issue with a squirrel cage fan. If you use a belt and pulley drive system you
could get the motor completely away from the fan blades.
I checked my Fisher catalog for lab hood fan material. I was wrong, Axehandle was right: the general purpose hood fan blades are of heavy duty
aluminum, those for the perchloric acid fume hood are stainless steel 304.
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Turel
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Idea
What about using Teflon particle spraypaint to inertify the exposed blades and backplane? I personally would just go all out and buy 2 or 3 cans, and
use them all. Spray consecutive layers to get a rather thick coating of teflon over the blades. Use an abrasive like sandpaper to score the metal to
increase adhesion.
A squirrel cage motor is the way to go. These are known as AC induction motors, or stepless AC motors. They have no commutators and in fact have zero
connection and disconnection phasing between mechanically moving parts and electrically charged parts.
Magpie, the motor will not be exposed to the flow at all if using a centrifugal fan. The design of the fan is such that air is drawn into the center
(at the origin) on the z axis if viewing the fan as a circle. The air does not pass continuously through the fan on the z axis.
Instead, it is accelerated rotationally and expelled along the x or y axis at the periphery of the circle. The fan blades protrude forward in the z
axis from a backplane in the x and y axes, shaped as a circle. The motor lies behind this backplane, attached by a spindle shaft to the backplane. The
motor is totally removed from the flow.
Using an AC Induction motor to power a centrifugal fan with either stainless or aluminum (perhaps teflonated) fan would provide an excellent quality
machine ready to evcuate a large air volume. I was at Home Depot today, and they have more than enough different suitable piping, tubing, and metal
conduit to perform the task of routing the gas flow.
Of particulr interest was the aluminum dryer conduit. Flexible like a flexible straw, and about 3.5 inches inner diameter. This would be perfect in my
opinion, as it is cheap and flexible.
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Geomancer
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Don't forget about cooling your motor. Much of the time blowers rely on passing the air flow over/through the motor in order to keep it from
overheating. Some open frame type motors will work fine if they are simply exposed to natural convection, but others want forced air cooling.
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