CFM ratings of Box fans

[mahfuz]

I apologise for asking too many quesitons about this subject.

Does any one know the CFM ratings of the regular household box fans? Or even the stand fans (you know the regular round 3 or 4 blade ones with wire casing)?

How come a $250 Jet AFS100B has 1000 CFM Max, and a much less powerful (1/16HP, $50) Airking has 2000 CFM. Is it false advertising? Is it popular brands charging for their reputation and added bells and whistles?

[JimD]

Mahfuz,

I don't know what the CFM rating of the old box fan I turned into my air cleaner is but my unscientific view (i.e. I've done no measurements or controlled experiements) is that it is adequate. I turn it on high when the DC is going and when using a palm sander. Otherwise it is on medium or slow so it is quieter. My shop is about 400 square feet.

Jim

[ExYankee]

The box fan has an unristricted air flow, while the DC is pushing into the filter bag, if you add afurnace filter on the box fan it will pick up some particulates but it will be real obvious that less air is traveling thru it.

[tfischer]

My current "air cleaner" is a box fan with a nice 3M filter on the back. I'm not sure if it's adequate for my shop (a 20x24ish garage) but I can tell you that it does help -- I have to blow the filter off regularly.

Someday I get (or build) a 'real' filter but this one's better than nothing...

-Tim