Shop Vac as fume extractor

[Mondo]

I am considering rigging up some sort of home-made fumes extractor system (flexible hose or hooded) to compliment my Lincoln MIG 140. As a suction source I was thinking of using my shop-vac. MGAW has it's own problems with C-25 drifing across the floor in my small garage, and FCAW is especially "fumey". Cold weather will be coming in a few weeks and I'd like to be able to work with the door closed and the shop-vac outside the window. Are the fumes going to be damaging to the shop vac motor? I ask because I know that sucking up spilled copier toner powder with a shop van can destroy it and cause a fire because the toner powder is electrically conductive and finer than the shop vac filter. I just don't know the chemistry of the welding fumes. Has anyone tried this or have any pro-or-con advice?

-Mondo

[Matthew]

sounds like it could work...you would have to put your actual shop vac unit out side or in a nother room because it just shoots the air raight back at ya... youll need a long hose..

matt

[Mondo]

... yeah, that was my plan. "...work with the door closed and the shop-vac outside the window."
You are right about me needing a long hose...

-Mondo

[imagineer]

I tried it with a wet/dry vac, running a hose from the drain opening out a window. In order to get then inlet funnel to pull the smoke in, it was too close to the work and messed with the shielding gas.

[Oldiron2]

The shop-vac motor is noisy, and uses brushes which might not last long when used continuously, but it will work. Some years ago, I found a new fan unit which was designed to be installed in a ceiling to supplement the suction fan, pulling moisture-laden air from laundry rooms and such. It had a 6 or 8" diameter, was quiet, efficient and fairly powerful, but I had nowhere to use it so gave it away. New in Grainger's, it cost a fortune but if you could find such a thing at a remodeling project or a surplus store, it would be ideal. You also could construct your own blower unit using a standard fan motor, once you try the shop-vac system first.
If you were working in a corner so the smoke was somewhat contained, this would work better. If the pickup is above you, removal of lots of air is required to get all the smoke.

An ionization filter mounted above, near the ceiling might be a better way to remove the smoke and particulate matter. It might also break down any carbon monoxide; I don't know for sure. So long as the welding isn't putting out any metal-containing gases which you breath as they drift away, this might do what you need and keep the heat in the garage too.

[Supe]

A buddy of mine used a box fan in the window. Made a sheet metal shroud for it, and ran dryer ducting over to where he was. Worked pretty well considering he had all of $15 in the whole thing!

[Matthew]

A buddy of mine used a box fan in the window. Made a sheet metal shroud for it, and ran dryer ducting over to where he was. Worked pretty well considering he had all of $15 in the whole thing!

Haha that reminds me of my grandma...

she used a box fan in the window, dryer tub attached and run up to ceiling with the other end dangling above her..

she was worried about second hand smoke around the children :)

[buhler]

The shop vac is a low cfm but high static pressure device. If you could find an old belt driven squirril cage furnace blower and put a slow motor with a small pully on it, like an old washing machine or dryer motor on it, you would have a quiet system that would give you lots of flow with the minimum pressure you need. When you mock it up, check the motor amps and if the amp draw is too high, block off some of the flow of the blower and the amp draw will go down.

[MoonRise]

Shop vac is a wonderful tool for many things, but sucking up large amounts of air/fumes is not really one of them.

And as Oldiron2 mentioned they are usually noisy. Really, really noisy. And typically not really made for long/continous usage.

A better 'scrounging' low-end choice would be a decent used kitchen range hood. Rig up ducting to exhaust outside.

Another possible choice would be a smaller dust collector, but DO NOT USE IT NEAR METAL SPARKS! You would be using the dust collector just for its air-flow, and again exhaust to the outside and bypass the dust collection bag.

Like imagineer mentioned, you'll have to put a shop-vac intake so close to the welding zone that you will interfere with the shielding gas.

YMMV.

[buhler]

there is always this from HF

[Mondo]

Great tips, all! This is the kind of info I needed. Thanks! :)
Good coupons, buhler! :cool2:

-Mondo

[patrickp]

I'm going to mount a bathroom exhaust fan in the middle of my shop. I'll run the exhaust outside using pvc pipe. I'll rig the fan up with a dryer vent hose which I can move around wherever i need it. It's not loud and the fan will last a long time. And the plus is that it won't pull out all of the heat. And if needed I can always install another one.

[Oldiron2]

You can get that accordion-style tubing in large diameter aluminum; I think 6 and 8 inch diameter. It can be hung from the ceiling with light wires, can be routed around things if needed, and is fairly cheap too. It may be easier to use that from the fan out to the exhaust port.

[patrickp]

this is true. it would be lighter and cheaper.

[Guy_48]

Hi, I had the same problems a couple of years ago. I got a fan from a propane furnace, the ones used for exhaust. I mounted it on a small frame, got myself a piece of flex hose at a mufler shop, hooked it all up and works well. I will post some photo's for you when I get home. I wired it up with some electrical receptacles as well, good source of power for my grinders etc.

Guy

[Teddco]

I use a 120 VAC 4"muffin fan, mounted on a 1" x 12" plank with a 4" hole in it, that takes a suction on
six feet of 4" black corrigated plastic drain pipe mounted on the plank opposite the fan. The plank is mounted on upright 1" thin-wall square tubing that has four outriggers welded at 90 degrees for a base. The plank slides up and down and is held at the desired location by a thumbscrew. The plastic pipe droops about 4" over six feet, but is self-supporting. I usually weld right outside my garage opening and it keeps fumes out of my face and blows them away from the garage interior. Not suitable for a totally enclosed welding area, but the muffin fan and plastic pipe may be cheaper than some of the other suggestions. However, plastic pipe/duct could be a fire hazard if the fan is powerful enough to draw sparks into its discharge path.

[Rojodiablo]

I did HVAC for many years. We always took the best squirrel cage blowers/ motors out of used furnaces and made bad to the bone shop ventilators out of them. They can run continuous, and are quiet. Plus, they were free, which was the right price for me!!!

[Oldendum]

One of the best fans I have is a little number that came off a junk pile - it's from an old industrial refrigerator or freezer. The motor is less than the size of a softball, made from cast iron, and has about an 8" blade. Whisper quiet, but it moves air nicely.