[fireguy268]

Hi, just new here, and I'm hoping someone can help me out. I've taken a few welding courses from the local CC and I have a nice welding area set up in my shop to weld and I've been slowly adding to my collection of welding equipment. It's just a hobby for me that I really enjoy. I have a question that I can't seem to get my head around. I've read many forums on the importance of keeping wind or breezes blocked when doing any shielded gas welding or it will blow the shielding gas away (I'm just doing mig not tig...yet). I guess the general rule of thumb is if you can feel the wind it's too much. I checked out the specs for Miller's MWX series extractor and it's rated at 875 cfm. To me that seems like a lot of air flow when the hood is just a foot or so away from the weld. With that being said, if the slightest breeze will blow away my shielding gas, Why or how doesn't a fume extractor generate a breeze and pull away the shielding gas when it's sucking up the welding fumes??

[weldin mike 27]

Hi there ,

You're right. Extractors can suck your shielding gas away but only if they are TOO close to the weld zone. Its about finding a happy medium between that and not capturing the smoke. With an adjustable head on your extractor just move it around untill you find the happy place. I think those things run on high volume low pressure type set up so as to cause minimal disruption to gas flow.

Mick.

[Otto Nobedder]

Hi, fireguy,

That "if you can feel the breeze" thing is bullshit preached by shops that are trying to keep gas costs down.

I've done MIG, TIG, and Fluxcore building ethanol plants, power plants, etc. on the great plains, and I promise you they don't care whether the wind is blowing or not. Your wages cost them more than the gas. If it's really bad, they'll have the scaffold guys build you a hooch to work under, but under normal conditions you just deal with it. For MIG and Fluxcore, a larger nozzle and gas flow of 60-75 cfh will handle a 10 MPH breeze. For higher than that, or gusts, you improvise a wind block to keep the bulk of it out of the immediate weld zone. Same thing for TIG. Gas lens, large cup, and I use an O2 regulator rather than a flowmeter in the field, so I can REALLY flow some gas when I need to (with a dry torch, gas valve on torch).

Just put the extractor close enough to handle all the smoke, and, IF needed, adjust the gas flow and/or nozzle size accordingly.

As an aside, one day it was blizzard conditions, snowing sideways at 40 gusting to 65 MPH, so they put away the fluxcore and I welded stick all damn day in the freezing cold.

Steve

[fireguy268]

Ok that makes sense to me now, thanks for the replies

Dennis