Garage Fume extraction

[mowogg]

I am slowly restoring a van in my single garage, and am getting a little concerned on the lack of ventilation while I am welding. I weld with both doors open, but it does tend to fill up with fumes after a few minutes. I wear the activated carbon masks, but I am thinking I should be doing more.

Looking on line you can buy a whole range of extraction fans. My question is what size would I need? Presumably it can be worked out on the number of air changes per hour? I am obviously keen to keep costs down, but I am thinking of a 6 inch extraction fan, possibly with trunking to extract around the area of work.

has anyone got any tips?

[MarkyB]

What is the garage made of?
Having a door or window in the other end from the main door would encourage air to move through rather than being a dead end.

[Matt]

6 air changes an hour would be more than sufficient in a small garage...

But its not simple to work out how pokey a fan would need to be - because its not how much "free" air it moves, its how much air can be sucked in that limits the flow

[moggiethouable]

Do you have a compressor?
I have used something called a ringjet, there are no electrics, it connects to a bit of 1/4 pipe for motive force and like a venturi utilising the coanda effect sucks loads of air and blows it out the other end of a 2" pipe when fitted.
http://www.beck-air.com/RingjetAirConve ... fault.html
A 2" bore unit is about £80.00 then you need tube attached to it to blow outside the garage.
The benefit I guess is you dont need more electrics and there are no moving parts.
You dont get out for nowt though, you will need 14 scfm to get it flat out, but extracts 400 scfm,
A small 12mm bore unit needs 6 scfm but extracts 200scfm.
The figures quoted are flat out though, you can regulate down for lower volumes.
Just a thought anyway.

[katy]

You say you have 2 doors, but where/how are they located?
A sketch or pics of the layout w/dimensions of the garage would be helpful in offering advice.

[tysonn]

What welding equipment are you using?Whilst I appreciate that one can never be too careful I can't recall ever welding a bead that was long enough and done in one operation that caused my garage to fill up with fumes?Usually its short runs and tacks etc done in such short bursts that any fumes disappear almost straightaway.Just my two pennorth!

[mowogg]

Thanks for the advice - the garage is single skinned brick, approximately 3 m width (with single up and over door one end), and a length of 6.5 meters. The car door out under a car port which probably restricts some free air movement. The single door and window is at the far end in a corner, which would suggest it should have good cross flow.

I use gasless Mig welding -I think the gas less contributes to the smoke. I don't have a compressor.

I was thinking I could install a 6 inch fan in one wall to pull air from within when I am welding?

[tysonn]

Yes I think you do get more fumes with the gasless migs.

[MarkyB]

You aren't welding Galvanised steel are you? That gives off some pretty noxious fumes, not good for breathing

[bigjim]

a 6" fan should create a nice throughflow but a 9" would be better , i have a 9" at the back of my garage and with half the front door open i get a nice throughflow

[bmcecosse]

I doubt a 6" fan is going to do ANYTHING.... I would buy a large (21") 'desk fan' and just use that to blow over your work area - or if you don't like that - to draw air away from you - and blow it towards whichever door seems to want to take the natural outward flow. Gasless does produce a bit (lot!) more fume.. But I see nothing wrong with it. Just don't stick your hand/head in the 21" fan while wearing the dark mask.....

[tysonn]

Yes gassing is bad enough but amputation at the same time would be a step too far.