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# High amp & pressure fan?

zoobie 09:54 12 Nov 2009
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I'm looking for a special high powered 120mm or 80mm axial 115AC fan that has high amps and pressure to force air thru cloth in an design experiment. Problem is, I can't find any. The highest amp fan I've found is only .26 amps. I see 12VDC fans all the time with high amps/pressure and can't figure out why I can't find the same in 115VAC. Is there a different formula used in AC vs DC? Where can I find 115VAC fans with high amps and pressure? I'm in the States. Thanks a lot

zoobie 20:49 12 Nov 2009

What I'm also saying is that DC amps must be waaay different than AC amps...

zoobie 21:00 12 Nov 2009

I can't edit the above post but I think I've figured it out. Since amps=watts/volts, if you're only using 12VDC, you bound to get a much higher amp rating versus 115VAC. Is this correct?
Thanks

zoobie 07:44 13 Nov 2009

Can anyone confirm the rating differences between DC and AV fans with the above post?

zoobie 22:01 13 Nov 2009

OTT_Buzzard 22:31 13 Nov 2009

zoobie:

amps = voltage / resistence, not watts / volts.

Your equation would give p = (v*i)/v = i

There is absolutely no diofference between and AC amp and a DC amp - the difference there is with the voltage signal.

I don't think you can run an AC fan from a DC power supply, or indeed the other way round. The way the commutators will be set-up will be different since an AC voltage supply doesn't need to reverse polarity twice a revolution.

Exactly how much power do you require from your fan? Fans are generally spec'd on diameter and airflow (cubic feet per minute, if you're American). You referred to pressure in your first post, what pressure do you mean?

OTT_Buzzard 22:33 13 Nov 2009

"since an AC voltage supply doesn't need to reverse polarity twice a revolution."

I explained that very badly: an AC power supply is sinsusoidal so reverses from positive to negative every cycle. A DC power supply doesn't, hence ned a splut commutator or equivelant via a brushless hall effect system.

woodchip 22:57 13 Nov 2009
woodchip 23:07 13 Nov 2009

Will a Air Dryer set on cool do for experiment?

OTT_Buzzard 23:26 13 Nov 2009

I'm genuinely intersted to hear what you are trying to do!

Just one caution in your quest for the worlds highest power rated fan: For the diameters that you are talking about, you really don't want anything that needs to draw several amps of power. If you did then you'd end up with the fan spinning at an insanely fast speed. If that doesn't shake the fan bearings to pieces, it will shear the spindle or cause so much air flow cavitation that it would become ineffective.

Very large diameter industrial fans will take a higher current load, but only because they have to shift the weight of the fan blades (especially a problem at startup) and have to move a much higher mass of air. But on the other hand, very large fans spin very slowly.

woodchip 23:33 13 Nov 2009

Just imagine the noise from a out of balance plastic fan running at high revs. and thats what you would get with a cheapo fan

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