Originally Posted by DaveLT
Bgears are 100CFM because they are overrated. And you DO NEED STATIC PRESSURE. Static pressure has nothing got to do with pressure by the way, fans of such calibre cannot possibly compress air
There is also no way for air to become static by being stuck at one location by higher airflow fans, it just moves. This is not natural convection
i have havemt heard of them being over rated and they may be i cant tell you from personal experiance and i also may be wrong about static pressure and how it applies to a fanhttp://www.asi.ksu.edu/doc5131.ashx
but if im not maybe im not using the correct term, im not the best at explaining things but i am good at understanding mechanics and applied mechanics of various things in my head.
lets say there is a fan with 5 blades spinning at 1000 rpm ( given the blade angles etc provide these results this is just for discussion no need to get into that much detail)
and at 1000rpm it moves 50 cfm and when you place lets say foam in front of it it causes resistance and as far as i can tell static pressure is the ability of the fan to hold a certain pressure against resistance , because the built up pressure would actually flow back thru the blades.
and thats brings me to
a fan with 10 blades spinning at 1000rpm moving 50cfm when encountered with the same resistance can move more air thru the resistance due to more blades. because each blade creates a certain amount of pressure and since the blades are closer together the area in witch they affect pressure is close together than with a lower bladed fan. now you could create a 5 bladed fan with wider blades for the same effect but need more torque to move it meaning more amps etc etc nevertheless im not an expert just learning and that was my understanding of static pressure when applied to case fans. fans.