Noble idea. Hepa filters have huge pressure drops, you would need a high pressure fan to blow air through it. There are are high efficiency standard filter pleats that can do the job with standard fans.

 

Ah, this comment led me to do the research I should have done at the beginning, thanks for nudging me in the right direction with this

Hepa filters have huge pressure drops, you would need a high pressure fan to blow air through it

What I took away from it all:

• HEPA filter is what you need to capture 99% of small particles (0.3 microns, possibly smaller), with the tradeoff of a high pressure drop. MERV15 filter would get ~85% of it with half (or less) the pressure drop.
• Activated charcoal filter is important if you're worried about VOCs, like solvent/cleaner/paint vapors, burn-off chemical vapors, etc.
• Putting a HEPA filter in line with a charcoal filter would be a HUGE pressure drop
• If I wanted to use HEPA along with activated charcoal filtering to ensure the air is scrubbed, I could just add more in-line fans (CFM remains the same, but static pressure increases at roughly a linear rate with additional fans in high-drop systems)
• If I do all of that, I don't need to vent outside at all, I could just vent my beautifully-scrubbed air into the rafters or somewhere else in the garage
• It would be more cost effective to buy one of those 3-stage ~500CFM suitcase-looking portable scrubbers for $450 than overbuild this
• As long as the exhaust isn't being vented into my neighbors yard next to the open window of their newborn's nursery, it's extremely unlikely that my occasional welding/shopwork would negatively impact anyone's health

 

I just go outdoors and let wind blow.

Dave

 

I just go outdoors and let wind blow.

So I'm having this problem with my TIG welds all turning black... :laugh: