Garage fume extraction

[DanGB]

Hello all,

I have a new MIG welding setup in my smallish garage. Have done some welding with the door closed and seems to get quite smokey after a short while.
Bit of reading says the the fumes are pretty bad for you. I'm just doing MIG on Mild steel.

I think I should probably invest in a fume extraction setup.
Have a large airbrick in the wall so looking to extract out of that.
But looking at what type of fan I should get.

Wondering how much CFM/ m3/H etc?

Its a roughly 4x3m garage.

Thoughts on something like this:
https://www.amazon.co.uk/Extractor-Ducting-included-CAM200-Clarke/dp/B004CRPP2K

or:

200mm version of this https://www.ebay.co.uk/itm/Inline-D...hash=item41787ceeb7:m:mnotBRjcQLMJ4BH4OlEDczg

Quieter (and cheaper) is better also

Many thanks.

 

[grim_d]

Open the door?

We have those clarke fans at work, mostly to keep us cool, they move a lot of air I'd say way overkill for what you need, and they are pretty loud.

Your second option seems reasonable value though, a bit of plastic corrugated ducting and you are good to go.

Would a few 120mm stealth computer fans, some ducting and some blue Peter skills work?

 

[dobbslc]

I used a normal in line bathroom extractor fan in my old garage to extract the exhaust fumes from my bikes when I'm setting up the carbs. I was really bad in there before after only a few minutes but with it plumbed in with some flexy hose it was perfect!
Dug it all out of a skip on site and have taken it with me to my new house ready to be reused.

 

[slim_boy_fat]

Open the door?

This. The worst, i.e. dangerous, fumes are from welding galvanised metal.

 

[DanGB]

Thanks all so far.

Although it's a garage, the garage door bit doesn't open so it just has a small door at the back, away from where I weld, so even if I leave the door open, which I often don't for different reasons, the files still tend to linger as there no air flow.

Previously read that a bathroom extraction type fan isn't gutsy enough, but perhaps it's ok for a small space.
The second option seems ok as it's pretty quiet and I would probably have some ducting above my work area.

Ps: I dont touch galvanised metal. Just clean mild steel.

 

[rtcosic]

4x3x (say) 2.4 = say 30m3.

At least 10 air changes per hour for general ventilation:

http://www.hse.gov.uk/pubnS/guidance/wl1.pdf

So a fan giving at least 300 m3 per hour is needed. Those cheap bathroom fans are nominally 85 m3/h but really about 50 at best, less if any duct-work is added.

Personally given the small price difference I'd go for the 150mm fan delivering nominally 700m3/h. This would be in 'free air' and would be much less with ducting added. We fitted one this size to the main bathroom in my son's house. The inlet grill, 3 metres of duct and outlet grill reduce the flow considerably. It just about keeps up with steam from a powerful shower, so not overkill. The noisiest part is the air flow through the inlet grill(s).

We bought one from Screwfix or Toolstation I think.

I subsequently fitted a 125mm version to in-laws bathroom and that is adequate but not exciting!

Don't forget you will need a large fresh air inlet at the opposite end of the garage.

 

[dobbslc]

You have to remember it will be used for localized extraction at the point of welding so the fumes will be straight up the pipe and out the building.

 

[DanGB]

4x3x (say) 2.4 = say 30m3.

At least 10 air changes per hour for general ventilation:

http://www.hse.gov.uk/pubnS/guidance/wl1.pdf

So a fan giving at least 300 m3 per hour is needed. Those cheap bathroom fans are nominally 85 m3/h but really about 50 at best, less if any duct-work is added.

Personally given the small price difference I'd go for the 150mm fan delivering nominally 700m3/h. This would be in 'free air' and would be much less with ducting added.

Thanks, thats great info.

 

[bigegg]

I use a bouncy castle blower

 

[DanGB]

In terms of air into the room, do i need any fans bringing air in, or, just some lourve or open/close vents on the opposite side of the garage on the door for example.

 

[bigegg]

In terms of air into the room, do i need any fans bringing air in, or, just some lourve or open/close vents on the opposite side of the garage on the door for example.

if you suck air out, fresh air will come in on its own.
the trick is to encourage the air to come in as far away from the fan as possible, so that all of the air in the garage is being replaced, and there are no stagnant areas.

if the extractor fan is powerful enough, louvres are all you need.

 

[rtcosic]

As an aside, in my shed I fitted a large 12V cooling fan from an old Rover 800 and run it off an old battery that sits permanently connected to a teeny weeny solar panel (about 30W nominal). Works for me but I normally only need it running for an hour or so at a time at long intervals.

It is mounted at the end of the shed opposite the door. I have a steel louvre panel salvaged from an old workshop cabinet screwed over a hole above the door. Despite this when the fan runs I have to push on the door surprisingly hard to open it. The fan draws a slight vacuum inside a leaky old wooden shed!

It draws enough air to keep the shed fresh when welding and grinding. When I spray in there (not 2k!) it clears the visible mist as quickly as it forms.

 

[skotl]

This was my first extraction setup - worked pretty well:

It used a fan like this:





It was ok, but then I bought an 8" diameter Nederman hose, and the fan couldn't keep up, so I bought an 8" fan like this:




And that was much better.

Fairly crap pic of it in action here:

 

[DanGB]

Thanks thats great, im probably going for a 150mm/6inch fan. The hose run is about 1.5metres so not bad.

Where did you get the black plastic sucker in piece at the wend of the hose? Ive seen them online but for about 60quid!

 

[indy4x]

Where did you get the black plastic sucker in piece at the wend of the hose? Ive seen them online but for about 60quid!

How about cutting down a large funnel

 

[skotl]

...Where did you get the black plastic sucker in piece at the wend of the hose? Ive seen them online but for about 60quid!

This?

That's part of the Nederman flexible extraction hose - they're normally a few hundred quid second hand, but I got this from an industrial auction for about £60!

 

[Farside]

How about cutting down a large funnel

Or a section of a black plastic bucket riveted / plastic welded to a piece of soil pipe the right size.

 

[Morrisman]

I’d definitely second running 6” flexi hose near to where you are welding. Evacuating the whole room with a fan is incredibly ineffective when you are hovering over a bench welding, unless the fan is right there in front of you.

You only need to watch somebody welding to see the fumes and smoke streaming off, though Mig is a lot cleaner than arc.

As an apprentice I occasionally worked in a fabrication factory, huge place, no ventilation. No wonder several of the guys from those days have died from various lung or throat related cancers......

 

[slim_boy_fat]

Fairly crap pic of it in action here:

That's a big trip hazard there, Skot

 

[skotl]

That's a big trip hazard there, Skot

Not for me - I'm up the other end!