# Does a fan's orientation with respect to gravity affect its flow rate or static pressure?

I just recently got a blower/centrifugal fan to use for layer cooling on my 3D printer and I'm thinking about how I want to mount it.

My primary question is exactly as the question title says: does a fan's orientation with respect to gravity affect its flow rate or static pressure? In other words, if I have blower fan in open space and air enters it from above to be blown out the side, will it move more air or do so at a higher static pressure in that orientation than if I were to flip it upside down?

My intuition says that gravity pushing down into the fan from above would be allow slightly better (faster?) flow of air than having to lift the air from below the fan, but I haven't been able to find any information on it.

• @JohnForkosh - But still! And the only thing I can think of for the practical application is generally, I should point the intake towards open air. Something tells me that my printer moving at a maximum of 0.125 m/s won't really benefit from being thrown into a wind tunnel. Mar 15, 2017 at 13:58
• How much air do you think will pass through the fan per second? And how far would you have to "lift" the air as it passes through the fan? Mar 15, 2017 at 13:58
• @biziclop - My particular fan is a 24v 4020 blower fan rated for 6.8 CFM and won't have any ducting before it, so there's no way for me (as someone without the skill to model fluid dynamics) to know how far the air would have to move to get into the fan intake. I'm more curious about fans in general though. Mar 15, 2017 at 14:06
• @MikeDunlavey - Could you put that in an answer? This seems obvious in retrospect, but I wasn't thinking about the air vis a vis buoyancy. Mar 15, 2017 at 20:34
• @JohnForkosh - The goal is not to cool the nozzle, but to cool the extruded plastic immediately after it heats the nozzle. The sooner I can get it to make a glass transition, the less sag the resultant parts will show. This is sometimes known as a "layer cooling fan" or "part cooling fan". 3D printers also usually have an extruder fan attached to the heat brake that keeps the hotend from melting whatever it's attached to. Mar 16, 2017 at 7:22