I mostly spray paint, clear, etc in a basement workshop. The setup is almost ideal but has no direct outside ventilation. However, the walkout is 14 feet away though an adjoining room and doorway. Whenever possible I open this for ventilation... and/or spray when family is gone and/or just before leaving the house... but that's neither purely ideal nor always possible. More often, I can't even vent the door because of weather (temp / humidity), so I have to spray indoors with it shut. This is not good and I don't like doing it for all the known hazardous reasons... but the other option is waiting for weather to cooperate with schedules, meaning nothing would EVER get done.
The other day I was following utility and plumbing runs in the workshop's unfinished ceiling and realized, DUH! There's a wall above that should be hollow (need to confirm, obviously) all the way the attic. In theory I could drop a pipe from the attic - hidden in that wall - down to the workshop ceiling, and put something like a bathroom fan there to suck fumes out of the workshop and blow them through the pipe and into the attic (and preferably on from there through a roof vent). It seems so stupid simple and even affordable (under $100): TOO easy. I'm an idiot for not seeing it sooner. So there must be something I am missing.
The constraint will be the size of the pipe I can fit in the wall; TBD but expect typical framing clearance, so let's say only 3 inches diameter. Is that even enough? How should I spec a fan to push X volume through a run of say 10 feet? Or 16+ all the way to the roof?
Are standard bathroom fans rated for volatile fumes (don't want to cause a fire), cuz it seems like most "hazmat" fans I've seen are larger than a ceiling vent.
I'm sure there are builder's formulas, but those usually deal with water vapor or conditioned air. When it comes to workshop fumes which may be denser and/or flammable, "houses" don't spec for that, but I'm not scaling to industrial gear either. Surely some of you can lend some advice. Last thing I want to do is rig up a DIY solution like I should be proud for thinking of it, only to discover it doesn't work well or is somehow more dangerous than what I was trying to solve.