# Ventilation when MIG welding



## graduate_owner (6 Nov 2017)

Hi all,
I have been reading about the dangers of breathing in welding fumes, and some web sites recommend using a local suction fan to remove these fumes. However I also read that a draught of as little as 4 to 5 mph can blow the shielding gas away resulting in porosity in the weld.
Does anyone have any advice on this?
What do people do about the fumes - do you use forced ventilation, wear a filtering mask, or just ignore the problem?


K


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## sunnybob (7 Nov 2017)

DO NOT ignore the problem. Just like sawdust problems, you have to protect the only set of lungs you will ever own.

http://blog.pksafety.com/how-can-you-pr ... ing-fumes/


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## novocaine (7 Nov 2017)

I don't stick my head in the smoke. 

extractors are low pressure high volume, you might have to lift your gas rate slightly but with a decent fume extractor positioned correctly it shouldn't be an issue. 

so now, when you buy a 200 quid welding set from machine mart don't forget your 2000 note fume extractor. 

It causes siderosis of the lung (welders lung) which is the depositing of iron oxide in to the walls of the lung, but the levels of iron oxide needed to reach this point are rather large, and it needs to be a constant exposure. 

The HSE define it as "chronic exposure" which is a nice way of saying they don't know more than it being a large dose over a prolonged, constant period. In short, if you are sticking a few bits of clean steel together every now and then in a well ventilated space, put your head out the smoke and you should be ok, (this is working in the flat, working vertical or overhead is actually a reduced risk as you aren't in the line of the fumes, which rapidly decay to larger particles which aren't breathable), if you are building the next humber bridge or welding routinely day to day then get the right kit (which you no dowt will have by that point). it's another case of taking the practices required to protect workers who do it day to day and applying it to a very reduced risk group without regard for exposure. 

If you are worried about it, spend an extra 20 quid and buy a mask, it'll be useful for other stuff too, you shouldn't need to buy an extractor for home gaming though.

now ducking and covering ready for the flame war that is about to head my way for having an informed opinion (NOTE OPINION) on the matter.


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## TFrench (7 Nov 2017)

I'm with novocaine. So long as its a well ventilated space and you aren't welding all day every day I wouldn't bother. All the site welders I know just have a normal welding mask - Only ones I see with respirator packs are bench welders in fab shops.


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## sunnybob (8 Nov 2017)

Strange worrying coincidence.
Today we met a couple we know who have just heard their son collapsed at work and is seriously ill in hospital in England.
he is a welder, and was working at height on a ladder when he became dizzy and nauseous. Luckily he got to the ground safely before collapsing. The unofficial diagnosis (there will be a H&E enquiry) is welders lung.
They are calling the hospital hourly to see if they need to go back to the Uk or not.

Dont take chances.


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## dynax (8 Nov 2017)

i use arc and gasless mig, and work outside, but i still wear a respirator, no point taking chances,


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## Woody2Shoes (8 Nov 2017)

Of course regular exposure is more dangerous than occasional exposure just like one cigarette probably won't kill you but 40 a day probably will - eventually - it's a numbers game. I only dabble in occasional brazing/welding but I always wear a good quality mask (esp. if lead welding!).

Besides, just iron, the welding rods/wires and the material being welded probably contain other additives/impurities like cobalt, chromium, lead etc. which are potentially much more dangerous in the lungs in small amounts.

I was told by a welder pal that the white smoke from anything anodized with zinc is particularly nasty, I forget the name he used for it.

Cheers, W2S


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## sunnybob (8 Nov 2017)

A friend was once a shipyard welder (back when we had some). I asked him to weld some brackets on my workbench, and when he saw the metal was galvanised, i got a very short two letter answer (well the answer was two letters, but accompanying adjectives were very long)


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## novocaine (9 Nov 2017)

Unlike smoking it really isn't 1 weld will kill you, it is a build up of iron oxide in the walls of the lungs, not a disease caused by something in there, so short term, you really aren't going to be affected, as I said above, it is Chronic exposure, long term (although cases within 1 year have been reported)

dizziness and nausea is more likely exposure to oxygen depleted atmosphere, like working in a confined space with CO2 argon mix (or keeping your hood down and letting welding gas build up under it, but that's a very unlikely thing to occur), neither are symptoms of welders lung although that isn't a perfect response. why was he working of a ladder?

obviously there is an increased risk of cancer from all of this (as the build up limits the ability of the lungs to clear other stuff out), so as I said above, if you're worried, spend 20 quid on a mask, it's your call. 

Be careful, there is a lot of inaccurate information based on conjecture and opinion out there on this subject, often presented by companies that sell ventilation equipment (how very cynical of me), but there have been genuine studies conducted which are available if you want to read up on it. 

NCBI has a good one that is peer reviewed. 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2827098/
Theres an NHS one too somewhere.


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## sunnybob (9 Nov 2017)

I'm only working on hearsay from the parents, so dont sue me yet. It was just such a coincidence hearing about only a couple of days after this post that I thought it worth reporting.
i will report back as and when I find the exact cause.


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## novocaine (9 Nov 2017)

fair point, don't shoot the messenger. sorry about that Bob.


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## sunnybob (9 Nov 2017)

no harm no foul. I wish I could set a permanent smiley in my replies. my off hand humour sometimes doesnt come across on a message board.


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## novocaine (9 Nov 2017)

snap. just have a look n the dyson or gtech thread for that.


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## -Matt- (9 Nov 2017)

I try and do very little galv welding, not always easy when there's the offchance of having to make a box out of galv sheet. 
At work we have a fume extractor with a movable hose and big funnel that you place over where you're working. This is fine for something small where you're only doing say 2" welds in a few corners etc, anything bigger/ more prolonged then it's out with the airfed mask as well.
We also use a fan system for MIG'ing aluminium too.
Normal mild steel we don't bother, don't stick your head over it and there's air circulating anyway for the very little smoke given off.


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## graduate_owner (10 Nov 2017)

Thanks for all the replies guys. I was also wondering what sort of fume extraction people use with mig welding. I know a breeze outside will blow the shielding gas away, and was wondering how to avoid that happening indoors. Would something like a Henry be too much suction? I was hoping to avoid having to wear a mask because I always seem to get fogged specs when I wear one. 

K


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## novocaine (10 Nov 2017)

graduate_owner":1drmy5ap said:


> Would something like a Henry be too much suction? I was hoping to avoid having to wear a mask because I always seem to get fogged specs when I wear one.
> 
> K



henry or any other vacuum cleaner for that matter is HPLV moving around 200 cfm, welding extraction is HVLP moving 800+ CFM. think about the bore of the pipe, a fume extractor is 100mm and up, the henry is half that.


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## sunnybob (10 Nov 2017)

If your specs are fogging, then your mask isnt fitted properly. Most folk dont fold the piece across their nose tight enough, causing the hot air to blow straight onto the lenses.


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## graduate_owner (10 Nov 2017)

I'm still not clear on this. Are you saying a domestic vacuum cleaner would be not enough suction to be effective, or would be too much suction and therefore suck the shielding gas away?

Would a normal 1HP dust extractor with a 100mm pipe be better, or worse?

Also, what happens to the fumes? With dust we know it hopefully gets trapped in the mesh of the filter, but welding fumes are gaseous, so should it be vented to the outside of the workshop? Or is just moving the fumes away from the welder and distributing them elsewhere in the workshop an adequate safeguard?

Sorry to be a bit obtuse here but this is something I have never considered before.

Regarding fogging of specs, I have tried several types of mask, including paper ones with and without valves, and the plastic ones with 2 elasticated straps that go around the head. Unless I tighten the straps really firmly ( not comfortable) I always seem to get fogged specs. It is a real nuisance. I have also tried applying washing up liquid to my specs as an anti fogging agent but that has not really worked. Some improvement but I find the film of washing up liquid degrades my vision, as if I seriously need to clean my specs. My eyesight has never been top quality even when a youngster so I don't want to lose any more clarity.

K


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## Inspector (10 Nov 2017)

Here you would go to a proper safety supply company or industrial supplier and they will fit test the masks they have to your face so that they are comfortable, effective and don't fog the specs. I suspect things are the same for you in your country. It won't necessarily be the cheapest mask but cheaper than buying ones that don't fit. So unless you have a very unusual face a mask can be found.

The vacuum cleaner isn't effective because the filters in it won't stop the fumes and the effective capture area at the nozzle is small. If the nozzle is placed too close to the weld it could affect the shielding gasses. A proper fume extractor draws more air through the 4" or 6" pipes/hose over a larger area at a lower velocity.

Proper fume extractors closer in size to equivalent woodworking DC's have special filters to capture the welding gasses (they ain't cheap) or they exhaust the air outside. Search for welding fume extractors to learn more. Those pages have links to the health hazards.

For hobby welding you are probably best to get a mask that fits and when you are not using it keep it or the filters stored in an airtight container. That way the filters will last a long time. The same mask with the appropriate filters can be use for woodworking, painting, solvent washing of car parts, et cetera.

Pete


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## novocaine (10 Nov 2017)

I've written a reply 3 times about air movement and pressure but to be honest I'm not happy with any of my responses. 

basically a hoover will pull the sheilding gas away because it's light.

do you have a beard? it's the reason masks don't work for me. although I have been known to shave for the right reason. 

I'd suggest going to a PPE supplier liker ross or similar and trying stuff on. 
they'll also have a spray for masks whichlyy sort you nicely.


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