What are and how are you welding?

IMO, anything that moves any air will be a plus. In most cases you do not want an artificial breeze. Fortunately most of the fumes are hot, want to rise naturally, your goal it seems to me, is make the fumes move away from your face, and exhaust outside the building. On the choice of tube size, I would think the 4" might be on the small size.If you can incorporate an viable speed fan (DC?), you could really fine tune each application. I think a fume extractor is very smart. up

Last edited by jcc; 01/25/21 01:21 PM.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.