Did you also stat out the static pressure? It's an important factor I don't see you mention and a lot of people over look it. It's especially important on some of those fans because the ducting and cooling they're pushing has restrictions and need a fair amount of static pressure to maintain the rated CF/M. Quieter fans generally have a lower static pressure rating too so you might not be getting the CFM you think for fans like the part cooling fan that has to push the air through the ducting around the head.

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IgorPartola 3 days ago | parent | next [-]

I don’t remember if I did but I can tell you that the performance I am getting from them is more than adequate. Cooling has not been an issue at all which I can measure and continuously monitor for some of these with the printer’s built in sensors. Basically for something like this use case the point isn’t to make it as cool as possible but cool enough to work correctly which these fans are more than able to do all day long at a volume level that is inaudible to me.

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igravious 4 days ago | parent | prev [-]

they said "volume per minute" so, yes, they were getting the CFM they wanted

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rtkwe 4 days ago | parent | next [-]

CFM is not a static value it depends on the 'load' applied to the fan, a fan with no restrictions will have higher CFM than the same fan facing no restrictions and the relationship between the CFM and the static pressure depends on the fan design. Low static pressure fans can't push air effectively through tubes or restrictions and the flow volume (CFM) drops because it cannot push the air on the output hard enough to flow. High SP fans usually have larger more closely spaced blades so that the air cannot escape back through the fan.

For example on radiators you need higher static pressure fans to push the air through the small space between the fins on the radiator, if you use a high CFM fan with low mm H2O (static pressure) the fan doesn't actually manage to push the rated CFM through the radiator. Same for ducting you see in 3DP applications.

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bradfa 4 days ago | parent | prev [-]

CFM is a measure of volume moved, generally quoted at effectively zero static pressure. Zero static pressure is rarely reality. All fans will have a static pressure vs airflow curve, which will vary based on the design of the fan.

I doubt normal people have the tools to measure fan CFM, especially when mounted into a product or enclosure, so presumably the OP was going based on stated specs.

	▲	rtkwe 4 days ago \| parent [-]
		On top of that low static pressure fans are generally quieter so if dB and CFM were their main criteria they probably didn't get the correct fans which is why I asked.