Solved! Highest CFM 40 — 60mm fan

YuliApp

Senior member
Dec 27, 2017
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Hello everybody,
i had from about 15 years ago a nice 40mm turbine from company called scythe, i cannot find anything comparable to replace the one which died recently. I had no stickers on so cannot find even original specs or name.

What i am after is highest possible CFM in 40 (might go up to 60mm) form which works at best from 6V to 12V.

It is not for cooling application so noise doesn't matter.

I was looking at replacement fans for 1U servers, but it is hard to find something with good specs and not just some replacement junk, so maybe some of you migh recommend.
TIA
 

BonzaiDuck

Lifer
Jun 30, 2004
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Those fans, like others like the 120mm units, have a variety of thickness specs. Some are 10mm thick. Some are 25mm thick (or 1 inch). I have a pair of Sunon Mag-Lev 40mm x 40mm x 25mm fans that (I THINK!) have top-end RPMs of 15,000. The CFM spec on those, that's something else, and I don't know what it is.

One would think given the matching size specs among these small fans, that the CFM is more or less linear with RPM. For such a small fan, the base CFM is low to begin with.

If you were to compare my Noctua 40mm x 10mm fan with the Sunon, I'm sure the Sunon fan would have a starkly higher CFM.
 
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YuliApp

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Dec 27, 2017
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Size doesnt matter really as it is for custom project. 15000rpm sounds about right.
Yes it is usually wider the fan higher CFM at same revolution / blade size.
I will look at the sunon, thank you.
 

Paperdoc

Platinum Member
Aug 17, 2006
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I'd be VERY surprised to find a small fan that runs 15,000 RPM. They don't even sell sealed HDD's that spin that fast! But remember that RPM does not really matter - it is air FLOW that does matter, usually expressed in CFM.

IF you are happy to go up to 60mm, that will be much better. For this application in an old system, I'll assume you need a fan designed for 12 VDC full speed and a 3-pin type (i.e., speed MAY be controlled by varying the Voltage supplied - not PWM). In the Noctua line, the NF-A4x20 FLX model can blow 5.5 CFM, whereas the model NF-A6x25 can blow 17.2 CFM. BIG difference! But you would want to ensure the full diameter of the larger fan can operate unimpeded.
 
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YuliApp

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Ah there are lot of fans 15-16000 area. Controlling is not needed as the wattage i am looking for is too high anyway (~30W) and would be costly.
Also I would hope to get close to 30-40CFM.
As said before it is an custom application so the device can adapt to any fan size, i just prefer as small as possible for practical reasons.

like this one

but i dont even know if i can trust the data. Would prefer some more reliable source / hands on experience.
 

Paperdoc

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Aug 17, 2006
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IP67 is a new added spec, and you will NOT find that for anything intended for computer case applicaions. That spec is for a motor/fan that is completely sealed against dust, AND sealed against water up to a depth of 1 metre. Delta is probably a good place to start looking. You also could look among suppliers of parts for the food processing industry.
 

YuliApp

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i thought also it would be mirracle, IP44 / 45 something in that range (big particle dust and droplets of water without pressure) would be more than enough but for start the PC one would be ok.
 

mindless1

Diamond Member
Aug 11, 2001
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The CFM ratings in use are going to depend on the pressure. Thinner fans at higher RPM to reach their free air CFM rating will have significantly more degradation in CFM than a thicker fan in many applications.

Here are 37 fans, 60mm x 32mm-38mm, all above 30CFM.
You may get better pricing elsewhere but Digikey's search makes it easier to compile a list of alternatives. I wouldn't get something with very high RPM, unless you really don't care about lifespan.