I used to work in Seattle-area shipyards. I was never a welder, but I sure worked around welders a lot. Very often I'd see this 3" metal flex tubing snaking its way around the ship. It would of course wind up in some little compartment where someone was welding, and it sucked the fumes. I used to see the electricians and sheet metal guys setting up these little sheet metal fans. They had two 3" input ducts (for sucker hose) and one square or maybe rectangular output duct, which they invariably cobbled with duct tape onto a 6" exhaust vent.
Some time ago, I obtained one of these little fans. No ducting. It works fine, and now I'd like to put it into service. Only problem is the 1970s were a long time ago and now I can't find the sucker hose anywhere. I'm confident I can find exhaust vent hose (spiral cloth ducting) but I never ever see the actual flex metal sucker hose anywhere. No welding supply stores, no industrial supply, noplace online I can find, nowhere. I'd settle for flame-resistant 3" flex ducting, which is what they use nowadays in the shipyards, but I don't even know where to buy that. Everyone wants to sell me an $800 "fume extractor" machine with big overarms and stuff. I can't afford that!
Anyone?
Grant Erwin Seattle, Washington