ConnieH wrote:this one is interesting:
larger size-wise - just under 8 inches, but still small enough to fit on a bucket lid with a modified duct tube. It looks quiet too...
The biggest problem with super-low RPM fans is they don't have enough oompf to push air when there are restrictions or a load. They're fine in perfect straight-through conditions (like the computer cases they were made for), but if you're trying to pull air through a thick filter (esp. one that's partially clogged with playa dust) and then push it through a couple feet of conduit, you need something that can push air with some power.
The spec to look at is the air pressure figure.
The 4000rpm fan (1.25A, 190cfm):
Air Pressure: 17.64 (wow, is that a typo?)
The 2000rpm CoolerMaster fans I bought (0.35A, 70cfm):
Air Pressure: 2.94 mmH20
The 1300rpm NZXT fan (.70A, 166cfm):
Air Pressure: 1.82 mm H2O
The 700 rpm CoolerMaster MegaFlow (0.28A, 110cfm):
Air Pressure: 0.595 mm H2O
I don't quite buy how that NZXT fan can really push 166cfm with those specs, but clearly, looking at the air pressure rating, it's a gutless wonder. That 4k rpm fan is off the charts, though. Tempting... but 55db is LOUD. And 1.25 amps is nearly twice the power pull than two of the 2k rpm fans (1.25A vs. 0.7A). Tough call... but I'm going to see how well I can make the two fans I already have (the 2k rpm 70cfm 0.35A fans) work, first.