Computer fan power?

[60acresbrewclub]

Is there is a way to figure out which computer fan will move more cubic feet of air per minute?

I have two fans that I sourced from a computer I found by a dumpster.
One fan is larger it is 3 3/8", 12v, and .19a
the other is smaller 12v, 3" and .41a.


I've used computer fans in the past to build stirplates, now I'm going to use one of these for a tower cooler in my kegerator.

i'll attach a picture incase it is of any use...the sizes listed were diameters of the fan not including their housing.

 

[day_trippr]

They're virtually equivalent wrt max air flow @ zero static pressure:
the top one is rated at 42.2 CFM while the bottom one is rated at 43.5 CFM.
The second one does have ball bearings though, could last longer/run quieter...

Cheers!

 

[Owly055]

Amps should be a pretty good indication, however a smaller higher RPM fan will draw more amps per CFM than a larger one pumping the same amount of air... the engineering being equal. Fans are like centrifugal pumps, they are not positive displacement devices. Interfere with the flow in any way, and it will be reduced, and power draw will decrease. A vacuum cleaner is a classic example of this. Put your hand over the nozzle and the motor revs up......not because it's working harder, but because it is working less. Computer fans have a lot of voltage leeway. The larger fan probably has a lower RPM or lower pitch, or both. Consider using it and bumping the voltage up to 15 or 19 using a wall wort transformer. I keep a drawer full of these in various voltages for just this kind of thing.
The error and error method works well for me................

H.W.