Well Robin, I assume you are referring to my comment, "a fan pulling the fumes away from the area". Please note, that I said, "pulling", you said, "blowing". Since you do seem interested in the subject let me just poke this in here.
I've used fume hoods for well over 30 years. Some were plumbed in from a central filter directly over my weld area, some were portable units and at home I’ve used some plane old window fans on the backside of the work. Again, I’ve used them with stick, mig and tig. If you do a little searching on the net you find hundreds of devices for removing welding fumes.
The amount of suck is directly proportional to the square of the distance, so a fume hood a few inches away from the weld area won't suck the shielding gas away from the weld area, it will simply gather up the fumes that are drifting out from it, very common in most decent welding shops now days since OSHA came on the scene.
Denny Graham
Sandwich, IL
