Dust Collector

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Frequently Asked Questions...

How do you determine the CFM of a dust collector?

The company claims their dust collector is 800 CFM,

Heres the spec

* Motor: 1HP, single-phase, 3450 RPM
* Motor Amp draw: 9 / 4.5
* Static pressure: 3.3"
* Impeller: 9", balanced steel, radial fin

Best Answer...


Using the attached link below, on section e and f It looks like you need more info.

CFM = FPM * (Pi*r2/144)

Where FPM = 1096.2*(Pv/D)^0.5, where Pv = Static pressure, in your case 3.3" and where D is air density, but most use 0.075 pounds per cubic foot as that is fairly close to normal room temperature air.

Where r = The radius of the round duct. That's what you're missing from the spec, but it might be a standard radius... 2" radius?


Using a single center point for measurement we get the maximum flow. This is good for advertising, but not realistic because the flow on the sides of the ducting is less. Dwyer Instruments found that reducing this maximum flow by 10% gives an accurate measure of total flow. This means we need to multiply our resulting CFM by 0.9 to know the actual total flow. So for marketing, they're probably using 800 CFM but in reality it is probably less.

Try that.