Tilted Forum Project Discussion Community - View Single Post

cyrnel · 07-12-2006, 09:10 PM

What's are the dimensions?

What's printed on the label? It should at least have manufacturer and model with voltage, current, possibly RPM. The blade cut doesn't look unusual but the motor looks robust. Guessing that's the difference.

Physics junkies will be better able to answer this but the ideal fan design for working against resistance is a positive displacement blower. (squirrel cage) A radial fan like those used in PCs are always at a disadvantage. They'll tend to blow backwards through the leaks as resistance increases or draw a vacuum and burn up from lack of cooling. (depends on push or pull) The only way I know to compensate is a powerful motor and close tolerance blade, but you still need to be careful about filter media and ducting resistance.

Try Heating/AC shops for media. They'll usually have large rolls or filter discards with usable material. You want the thin backing layer. It'll look much like the foam included with these:

but big filters use a wide variety of thicknesses.

If you want much air volume with filters, and without a bunch of noise there isn't much to do besides increase fan area. I try to run the biggest baddest fans that'll fit for intake, cut to 7V, and drawing through filters. The goal is slightly positive case pressure to keep things clean without howling intake. If the room's quiet it's still noticeable.

07-12-2006, 09:10 PM	#5 (permalink)
cyrnel Adequate Location: In my angry-dome.	What's are the dimensions? What's printed on the label? It should at least have manufacturer and model with voltage, current, possibly RPM. The blade cut doesn't look unusual but the motor looks robust. Guessing that's the difference. Physics junkies will be better able to answer this but the ideal fan design for working against resistance is a positive displacement blower. (squirrel cage) A radial fan like those used in PCs are always at a disadvantage. They'll tend to blow backwards through the leaks as resistance increases or draw a vacuum and burn up from lack of cooling. (depends on push or pull) The only way I know to compensate is a powerful motor and close tolerance blade, but you still need to be careful about filter media and ducting resistance. Try Heating/AC shops for media. They'll usually have large rolls or filter discards with usable material. You want the thin backing layer. It'll look much like the foam included with these: but big filters use a wide variety of thicknesses. If you want much air volume with filters, and without a bunch of noise there isn't much to do besides increase fan area. I try to run the biggest baddest fans that'll fit for intake, cut to 7V, and drawing through filters. The goal is slightly positive case pressure to keep things clean without howling intake. If the room's quiet it's still noticeable. __________________ There are a vast number of people who are uninformed and heavily propagandized, but fundamentally decent. The propaganda that inundates them is effective when unchallenged, but much of it goes only skin deep. If they can be brought to raise questions and apply their decent instincts and basic intelligence, many people quickly escape the confines of the doctrinal system and are willing to do something to help others who are really suffering and oppressed." -Manufacturing Consent: Noam Chomsky and the Media, p. 195 Last edited by cyrnel; 07-12-2006 at 09:22 PM..