Author Topic: GHETTO microwave/fume hood  (Read 12991 times)

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  • Guest
GHETTO microwave/fume hood
« on: July 31, 2004, 09:21:00 AM »
you will need  these items  


 1  vacuum pump -OIL DRIVEN  to eliminate explosions (would not bee a good thing during a batch)
 SWIM's is a model used to evacuate refrigeration systems

 2  microwave oven

 3  3/4 inch pvc fittings and pipe of various types depending on your setup desired.other tubing will likely be needed depending on the vacuum units fittings,gas

welding hoses worked well on SWIM's

 4 small box fan to cool down pump on extended uses-it will heat up

5 (optional) spare or old water heater this quietens the system down greatly and makes a good resevoir for regulating the vacuum.When first experimenting with

this setup the vacuum was too strong, SWIM boiled up a bunch of alchohol with out any heat and sucked it away ( with some fed in it) this was while using the

vacuum chamber. a stainless steel presure cooker. This setup has many uses from distillation at low temps, fume hoods, vacuum filtration, vacuum dessication.
SWIM could go on and on, but won't go off on a ramble

You need a place to pump it to, SWIM piped in a drainline to a sewerline cleanout in the lab.  2" abs pipe with a wad of tape and rubber on the end to seal it, you

get the idea.To this was atached a Y  fitting, one opening has a funnel for pouring things,the other has a 2' / 3/4 adaptor on it, this is outlet for vacuum. this  line

does not  havebe a special typesturdy garden hose will do,its only a low pressure exhaust line
prep microwave- remove cover ( careful about capacitors they'll shock the piss out of you if you hit one) tape closed all openings you find. use a good tape, and

remove  lamp thats usually inside of a screen because this might melt tape, your air intake will be the door, remove the plastic sheet inside of door screen ( this

was good for taping some of the openings, its heat resistant) then remove plastic shield on front door( dont be afraid of radio waves) the metal screen is the only

barrier to them, this YOU WILL NOT REMOVE ! it also functions as sort of a blast shield now i suppose!
Now attach to the rear of microwave, close to the top of the inside compartment ( helps fumes flow ) one 3/4 inch male adaptor, you wil need a hole saw or drill.

Inside use a locknut(the ones on electrical boxes are same size. or cut off a piece of a female adaptor to use. Attached to this fitting will bee a pvc piping 3/4  in

size to wherever you have the vacuum or reservoir. or in this case the cold water inlet on a water heater

valves/bypasses. Then from hot water outlet(of water heater) attach pvc pipe to your vacuum chamber [microwve oven in this case, or fume hood, pressure

So basically u should have this setup
 air moves into microwave through the unobstructed screen in front door, is pulled out of the otherwise sealed compartment through 3/4 inch pvc lines, then from

there into a reserve tank, or straight down the drain pipe, IF USEING  CORROSIVE CHEMICALS  CONSTRUCT SOME SORT OF GAS SCRUBBER  !! THE

YOU NOW HAVE A CLOSED SYSTEM, modify as u see fit.


  • Guest
« Reply #1 on: August 01, 2004, 01:13:00 PM »
I dont understandt this, but would love to see a picture :-)
Doo you have plastictubes into your MW'oven ?


  • Guest
good thinkin'
« Reply #2 on: August 01, 2004, 07:09:00 PM »
sounds like an interesting setup.... how much faster is it when evaporating stuff? i would imagine that the constant airflow would help speed things up (and since its inclosed, it would also prevent dust and other debris from getting in the pan!)


  • Guest
Pics will be posted
« Reply #3 on: August 02, 2004, 10:58:00 AM »
when i can locate the damned camera charger. pipe is attached to rear of microwave, looking into it you'll see a hole 3" from the top on the rear wall.


  • Guest
« Reply #4 on: August 02, 2004, 12:20:00 PM »
And iff it's in plastic a lot of MW will come out of itt


  • Guest
Your probably better off buying the bits and...
« Reply #5 on: August 02, 2004, 11:58:00 PM »
Your probably better off buying the bits and pieces. A proper (saparkless, chemical resistance to most chemicals) fan, a carbon filter and ducting.

With no fuss or hassle.


  • Guest
uWave fume hood
« Reply #6 on: August 08, 2004, 08:26:00 AM »
Thanks for posting this design, ES. It's quite an elaborate sounding design and I don't understand it all on first read. It would be a very useful thing to have, however, so SWIP is going to consider building it.

To what you've written I might add that anyone nervous about working around the large capacitors can discharge them by shorting the terminals with a large screwdriver, prybar, etc. Just don't hold on to an uninsulated portion of whatever tool you use when you do it. Also, be advised that the spark might burn a little notch in your tool at the point it touches the capacitor terminal. But better to burn that that your arm.

On the subject of the fan, if you buy one, make sure it has a brushless motor, which is the only kind that you can be sure won't make sparks!



  • Guest
very simple
« Reply #7 on: August 08, 2004, 10:25:00 AM »
basically its a microwave with a small hole drilled in rear of the unit, this side faces a sheetrocked wall (drywall) so the radio waves wont reflect,the interior venting has to be closed off as to eliminate sparks,the front door has the plastic layers removed thus exposing the underlying metal screen. This  is now the  air intake, the exhaust is driven by a vacuum pump hooked up to the PVC piping. Microwaves dont reflect off plastic, so theres no risk of exposure to microwaves,
Soon as i get some time off from work I will post some pics of the setup,


  • Guest
A vacuum pump is no substitute for a fan!
« Reply #8 on: August 09, 2004, 10:35:00 AM »
A vacuum pump is no substitute for a fan!


  • Guest
re: Vacuum pump no sub. for fan
« Reply #9 on: August 15, 2004, 09:01:00 AM »
Good point. It would have to be one hell of a vacuum pump that could keep up a flask of boiling whatever. I could see it working if a container was attached directly to a large pump, but considering it has to pull a draft from the open front of the oven. . .???

Seems like it might be better to use a brushless fan and duct the exhaust past the water trap on a drain pipe. If you have PVC pipes, however, solvent vapors would be awfully hard on them and you might melt a hole.



  • Guest
Seems like it might be better to use a ...
« Reply #10 on: August 16, 2004, 04:52:00 PM »
Seems like it might be better to use a brushless fan and duct the exhaust past the water trap on a drain pipe.

You could also consider placing the rxn flask next to an open window, with a network of computer towers alligned to blow the fumes out the window, and plot a vector field to predict the velocity of the fumes.

Carbon filter, ducting, with the fan sucking the virgin fumes through the active carbon filter is the way to go.

For the poster's design, I'd replace the microwave with a cardboard box and sticky-tape.  ;D


  • Guest
tower, vector field
« Reply #11 on: August 23, 2004, 04:12:00 AM »
"You could also consider placing the rxn flask next to an open window, with a network of computer towers. . . "

Now you're talking! But computer cases? Please.

No, far better to costruct an array of old pentium processors, pump in liquid nitrogen to cool them to near absolute zero, align your coils and with enough EMF you can rely on the Hall effect to create a vortex that will launch those damn vapors to alpha centauri.

"Carbon filter, ducting, with the fan sucking the virgin fumes through the active carbon filter is the way to go."

Of course it's hard to argue with that.



  • Guest
« Reply #12 on: August 24, 2004, 05:56:00 PM »
Swim has a microwave that has a metal grill in it, How the fuck that works I don't know, Anyway back to the point, Swim drilled a 1" hole through the top center of the unit and has a bradded hose running through it with a 8" funnel attached and pulled tight to the top of the oven. A small squirrel cage 12 volt blower is manifolded down to the tubing. A 1" hole was drilled through the bottom far corner for an inlet.. This system rocks. A 1000ml beaker has about 1" clearance under the lip of the funnel and you can adjust the funnel down for smaller beakers. The exhaust can be dealt with in many ways but blowing directly outside is Swims choice.. Dwarfer told me how to build it years ago and its safe and effective..


  • Guest
Very effective for heating of solvents
« Reply #13 on: August 29, 2004, 04:23:00 PM »
that was the original use of it,while boiling 2 liters of xylene @ 110 deg centigrade, NO SMELL's detected whatsoever.
its also excellent for kerplunking.
No microwaves come through plastic pipe. that frequency spectrum is very directional, yes there will be some coming out the hole, but they are rendered harmless by the sheetrock wall,


  • Guest
might read this post
« Reply #14 on: August 29, 2004, 04:33:00 PM »
Here is some more talk abouth the wonder of the MW's

Post 448477

(hest: "AMT in the MW oven", Tryptamine Chemistry)