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-   -   Fume Extractor (http://www.hotrodders.com/forum/fume-extractor-64408.html)

johnnymopar 06-16-2005 09:11 PM

Fume Extractor
 
I find sometimes that i'd like to have a fume extractor but i don't want to fork out any $$. they are kind of pricey so i was thinking i could either rig up some kind of blower and duct-line to suck the air outside, or i could make a box with a fan in it and have a couple charcoal filters. i don't really want to cut a hole in the wall to vent the air and i don't want a 20' hose dragging around the shop. do you think my airbox/charcoal filter idea is doable? i'd like to do it that way because i'll have less hose to trip over and i can use a smaller/cheaper motor.

thanks for the input.

JB

61bone 06-19-2005 11:35 AM

You didn't say if your extracting welding or paint fumes, but here's what I did.
For my welding bench, I snagged a stove hood from the steel recycler and vented it outside.
For paint, I got an old truck sleeper (40"), stripped it outand sealed the walkthrough with plexi. I used the 12v lights that were in it for light, powered by a small batt charger. A heater fan provides pull through ventilation. Inlet and outlet air are filtered. Outlet air is exhausted outside to prevent vapor buildup.
A carbon filter big enough to do any good is going to be really pricey.
There are electric smoke eaters that do a good job and are portable to the job with a little ingenuity. but $$$$$

johnnymopar 06-19-2005 08:16 PM

thanks for the reply. i forgot to mention that this is for my welder. i could make a small filter box with fan. then it would be portable and i'd just have to plug it into an extension cord.

JB

propaniac 06-29-2005 02:36 PM

How about using an old evaporative cooler?

johnnymopar 06-29-2005 05:14 PM

i don't know anything about those, how would that work?

JB

propaniac 07-01-2005 09:12 AM

Out here in the hot dry southwest we have evaporative coolers or "swamp" coolers. They are basically a box with a blower in it. The sides have panels that hold aspen shavings(or foam etc..) water trickles down through the panels soaking the pads. The blower pulls the air through the pads and the process of evaporation cools the air.
Anyway they are pretty common here, sounds like not so common where you are. I am sure if it will do what you are looking for but if it is you could order one. A small window one is around $250.00 us

John

Gearhead forever 07-01-2005 09:22 PM

Johnny...I was in your town today....Beautiful place. Great park along the river.

As for your fume hood, can you vent it outside by other means? (make a window plug or???) You can always use a small BI fan or furnace blower to vent out the fumes of your shop. I don't want to cut holes in my wall either. I'm getting my roof re-shingled and having extra roof vents installed. I'm planning on using one of the vents as my exhaust outlet. The big drawback is losing all the heat in the winter.

johnnymopar 07-02-2005 02:28 PM

thanks for the replies, guys.

i can vent it outside, there is a hole in the wall where there used to be a woodstove, 6" pipe. i could rig up something for that but then i have to wire in a fan and then have a 20' or so, hose flopping around to wherever i'm welding. i thought if i had a small filtered box with a fan in it and short hose, ie. 3'-4' then i could just plop it down wherever i'm welding and use an extension cord. the other way would probably work better, but would just cost more $$. maybe if i could hang it up out of the way it wouldn't be so bad. i could get an inline 6" fan and then reduce it down to a 3" or 4" hose.

JB

BTW, yes, Stratford does have a very nice park system.

Gearhead forever 07-03-2005 02:44 PM

An in line fan would be pitiful at best, especially with a 3 or 4" intake hose. I would think if you wanted to utilize the 6" outlet, you would need to use a high speed or high pressure blower to get any real results. Just my 2 cents

xntrik 08-14-2005 11:15 AM

exhaust fan
 
Quote:

Originally Posted by Gearhead forever
An in line fan would be pitiful at best, especially with a 3 or 4" intake hose. I would think if you wanted to utilize the 6" outlet, you would need to use a high speed or high pressure blower to get any real results. Just my 2 cents

AMEN Brother.

Try a house furnace squirrel cage blower with as big a line as possible pushing air outside. Think 2000 cfm. Set the blower near you and push the air out through a big hose. You need lots of volume or you'll never get rid of the fumes.

Henry Highrise 08-14-2005 01:36 PM

A squirrel cage blower is the way to go. If you cut a hole in the wall and mount it with some blow out louvers it will work great. You need to leave a door or window open a little bit when running this, but it will change the air in your garage or shop pretty quick.

Festive57 08-14-2005 09:04 PM

I design blowers and exhausters for a small company here in Pennsylvania. Sorry nothing small enough to help (they will literally blow the whole garage away, they are the size of a two story house) Any way, what size of fan were you thinking of using? If you are thinking of a regular household box fan, it could work, but where are you planning for the air to go once you scrub it thru your filters? If you suck the welding vapor thru a filter, the filter will only scrub what you can see, the outlet of the fan will still send the micro-toxins out the discharge side of your set up (ie. it will still stink up the inside of the garage). What you need to do is vent the air to the outside of the garage as many of the others have indicated, you also have to pull fresh air in (no matter what you thing air has to come in from somewhere, cracks, holes seams (the better or more finished the garage is the worse your welding vapor will be... for example an old block garage will "leak" more than a new finished dry walled garage). My thoughts are build a box around the 6" vent in the wall where the heater used to vent. Put the fan in exhausting towards the 6" hole, then build a transition down to half the size of the fan (ex. fan is 24" in diameter then build a transition down to a 12"sq. (if it is a square box fan) then build a square duct at least 2 times the diameter in length approx. 4ft. long (48"). you can incorporate the filter at any point in the duct...

This is the reasoning... it does not matter what the hole size is in the garage wall (although getting any smaller than 6" will be to small) with it being boxed in you are creating a point of pressure build up, the atmosphere outside will be less than what will build up in your box on the inside of the garage, thus the air will want to scavenge out the hole (kind of like. the burnt air full mixture escaping out the exhaust valve a combustion engine, with the exception of the air is not super heated). The pressure that will build up will be due to the induced draft you are creating thru the 48"lg. duct. when the fan is running, experiment with a window at the opposite side of the garage, open it or close it as you weld until you get the proper mix of air flow... You will know when you find the right mixture. I exhaust my paint fumes thru a 7" diameter duct thru the roof of my garage in this manor. My whole set up cost me around $20.00 (using the duct an old 6" personal fan and an old wood burner exhaust pipe with cap etc.) I have to open one of my garage windows about 6" to get the flow right... of course a little less in the summer a little more in the winter due to the density of the air (hot to cold).

Now, I know I am long winded, but if your fan is round you could use light gage sheet metal pop-riveted together, you could make a round to round reduction with the light gage material (if you need I can layout what you want), if your fan is in a box you could build a box from old paneling and some 1"sq. wood stock (just seal up the cracks with latex caulk). next, you want at least 48" of duct run. A straight run is alway's best but you could build it vertical, transition from the box to the ceiling then make your run etc. If I get a chance, I'll draw a quick sketch to illustrate what I am speaking of.
Remember, I only design fans, I am not an engineer yet (currently going back to school to become one someday) I have 13yrs of experience, but I hold no responsibility or liability, this is just merely a suggestion (mine works fine).

On a windy day, the wind blowing by helps to create a greater suction which makes me have to turn up my gas on my welder to keep my gas from "blowing away".

Good luck
Bill

johnnymopar 08-16-2005 09:39 PM

thanks for the info guys.

i was kind of leaning toward something portable as there isn't any power on the end of the shop where the pipe goes out. i'd have to run a switched circuit over there.

we'll see how it goes.

later,

JB

xntrik 08-17-2005 12:14 AM

Quote:

Originally Posted by johnnymopar
thanks for the info guys.

i was kind of leaning toward something portable as there isn't any power on the end of the shop where the pipe goes out. i'd have to run a switched circuit over there.

we'll see how it goes.

later,

JB

Furnace blowers are 110 volt and easily run by a "wall switch" circuit. Been there, done that.


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