This is often a confusing question. Best to think of it this way, if I put 3 fans blowing in and 2 fans blowing out at 100 cfm each ....
how much air is blowing in ? it's not 300
how much air is blowing out ? It's not 200
If those answers were true the case would explode.
fans like pumps move their "liquid" on the basis of a curve...the higher the resistance, the further they drop down on the curve.
In the above example, that 3rd fan blowing in would increase case pressure allowing the two exhaust fan to move a bit more than their 100 cfm rating. That extra case pressure would drop their flow by a bit also and you'll prolly wind up with the two exhaust fans pushing out 120 each and the three intake fans pushing 80 each.
Keep in mind that at a certain point, pushing more air thru closely spaced fins doesn't do much because it creates too much turbulence. Prolimatech tech Support for example recommends no more than 800 -1200 rm fans.
how much air is blowing in ? it's not 300
how much air is blowing out ? It's not 200
If those answers were true the case would explode.
fans like pumps move their "liquid" on the basis of a curve...the higher the resistance, the further they drop down on the curve.
In the above example, that 3rd fan blowing in would increase case pressure allowing the two exhaust fan to move a bit more than their 100 cfm rating. That extra case pressure would drop their flow by a bit also and you'll prolly wind up with the two exhaust fans pushing out 120 each and the three intake fans pushing 80 each.
Keep in mind that at a certain point, pushing more air thru closely spaced fins doesn't do much because it creates too much turbulence. Prolimatech tech Support for example recommends no more than 800 -1200 rm fans.
