Fan guru required to calculate CFM

[KELL5]

I'd like to find out the amount of air I'm moving through all my fans. I am unsure as to how you calculate cfm especially when fan speed is increased over maximum rated speed, so would appreciate it if any fan guru's could calculate it for me.

This is my fan setup.

http://thumbnails2.imagebam.com/2574/22b56e25739062.gif (http://www.imagebam.com/image/22b56e25739062)

120mm @ 18v

http://thumbnails11.imagebam.com/2574/1ea8cd25739064.gif (http://www.imagebam.com/image/1ea8cd25739064)

2x 90mm @ 18v

^^ These 3 thermaltake fans feed air through my true. Is it possible to calculate the cfm for this?

http://thumbnails11.imagebam.com/2574/ae191b25739066.gif (http://www.imagebam.com/image/ae191b25739066)

80mm Akasa @ 18v

I have 3x of these. One is located on my NB, one is located on my RAM and the final one is connected to my 9800GTX+ fan intake.

Is it at all possible for someone to calucalate the cfm of these fans (even approx is fine)? I'm just curious as to how much airflow I have though my fans.

Thanks in advance.

:)

[Serra]

Increasing volts does not linearly increase fan rotation, and blade design et al change the CFM as well... so just saying "120mm fan @ X volts" tells us pretty well nothing.

Which is, of course, not to even mention anything about static pressure which is a nontrivial concern.


Anyway, that was long-winded... but if you want to really test it yourself, I'd suggest getting a Kestrel (or similar) wind measuring device (kestrels are small hand-held units) and then using that to create some CFM calculations - you'll find the forumla for it all over the 'net (in fact, some Kestrel units will calculate the CFM of the fan for you once you enter the fan size and spindle size).

[KELL5]

Anyway, that was long-winded... but if you want to really test it yourself, I'd suggest getting a Kestrel (or similar) wind measuring device (kestrels are small hand-held units) and then using that to create some CFM calculations - you'll find the forumla for it all over the 'net (in fact, some Kestrel units will calculate the CFM of the fan for you once you enter the fan size and spindle size).

thanks for the info :)

much appreciated.