Air Filter/Water Seperator Sizing

by Dan

Does oversizing the air filter negate its water separating ability?

I assume that an adequate sized air filter; (40 Micron) 1/4 NPT Air filter would swirl the saturated air better and have a higher centrifugal forced creating a better water separating effect compared to a larger bowled 3/8 NPT Filter?

Is a smaller diameter bowl preferred if the CFM rating is the same?

Comments for Air Filter/Water Seperator Sizing

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Nov 26, 2018
Compressed air filters
by: Bill

Question has been moved to the Compressor Filter section.

The flow rates through a 1/4" air filter are large, particularly with a 40 micron filter as the element.

As the filter size steps up to the 3/8", assuming it's a true larger filter instead of just a fitting size increase, the flows are huge.

Regardless, compressed air flows at extremely high velocity and the relative size difference between the mini- and the regular full-sized filter will little reduce that speed.

I would choose a larger filter only because the CFM rate of air use was approaching the maximum capacity of the smaller.

If not, then to my mind there is no benefit to adding the higher cost of a larger air filter to the equation. I do not believe you will get better filtration and water separation by moving up a filter bowl size.

You may, however, get an auto- float drain with a larger filter that may not be available in the smaller version. Making sure the bowl is emptied long before the liquid level gets to the "quiet zone baffle" of the filter innards is critical to the function of the filter.

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