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Fans, Radiators, Static Pressure, and Resistance

Ryoutarou97
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CFM (Cubic Feet per Minute) seems to be a straightforward concept- how much air a fan can move in an amount of time. Static pressure I find more confusing. From what I can tell, it's the resistance a system has to the flow of a fluid, so why is it in mm/h2o? To the best of my knowledge, pressure is measured in force/area (Pascal = n/m^2).

 

I understand where to use static pressure fans- on rads and heatsinks- and I sort of get that it's because there's not a clear path for the air so you need large blades to prevent the air that was just pushed from leaking back out. But I have no idea what static pressure is.

 

And once someone explains that, how much does a radiator prohibit flow? I was watching a recent video from Jay in which he mentioned that he had less intakes than outtakes which worked because the outtakes were pushing less air due to having rads mounted on them. This sparked my curiosity since I am the type of person who would really like to be able to calculate intake and outtake airflow to perfectly balance pressure, noise (fan RPM), and cooling performance.

Tip to those that are new on LTT forum- quote a post so that the person you are quoting gets a notification, otherwise they'll have no idea that you did. You can also use a tag such as @Ryoutarou97 (replace my username with anyone's. You should get a dropdown after you type the "@")to send a notification, but quoting is preferable.

 

Feel free to PM me about absolutely anything be it tech, math, literature, etc. I'll try my best to help. I'm currently looking for a cheap used build for around $25 to set up as a home server if anyone is selling.

 

If you are a native speaker please use proper English if you can. Punctuation, capitalization, and spelling are as important to making your message readable as proper night theme formatting is.

 

My build is fully operational, but won't be posted until after I get a GPU in it and the case arted up.

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It's just another way of measuring pressure AFAIK. 1 mm/H2O is equivalent to about 9.8 Pa

Intel Core i7-5820K (4.4 GHz) | Gigabyte GTX 970 G1 Gaming | Corsair Vengeance LPX 16GB  | 2x 360mm Custom Loop (Noctua iPPC) | ASRock X99 Extreme6 | Samsung 840 EVO 250GB | Fractal Design Define S | Corsair HX750 | Windows 10 | Corsair M65 RGB PRO | Corsair K70 RGB LUX (CherryMX Brown) | Beyerdynamic Custom One Pro & Creative Sound Blaster Z | Nexus 6P (32GB Aluminium) | Check out my setup: Project Kalte Here!

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It's just another way of measuring pressure AFAIK. 1 mm/H2O is equivalent to about 9.8 Pa

Thanks for the answer, but if it's equivalent to Pa, wouldn't it also be force/area? Why length/H2O? How does one even divide by H2O?

Tip to those that are new on LTT forum- quote a post so that the person you are quoting gets a notification, otherwise they'll have no idea that you did. You can also use a tag such as @Ryoutarou97 (replace my username with anyone's. You should get a dropdown after you type the "@")to send a notification, but quoting is preferable.

 

Feel free to PM me about absolutely anything be it tech, math, literature, etc. I'll try my best to help. I'm currently looking for a cheap used build for around $25 to set up as a home server if anyone is selling.

 

If you are a native speaker please use proper English if you can. Punctuation, capitalization, and spelling are as important to making your message readable as proper night theme formatting is.

 

My build is fully operational, but won't be posted until after I get a GPU in it and the case arted up.

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Thanks for the answer, but if it's equivalent to Pa, wouldn't it also be force/area? Why length/H2O? How does one even divide by H2O?

I don't think forward slash in this unit of measurement indicates division, it probably indicates the word "per" or "of", millimeter per water or millimeter of water. 

 

http://www.aqua-calc.com/what-is/pressure/millimeter-of-water

Intel Core i7-5820K (4.4 GHz) | Gigabyte GTX 970 G1 Gaming | Corsair Vengeance LPX 16GB  | 2x 360mm Custom Loop (Noctua iPPC) | ASRock X99 Extreme6 | Samsung 840 EVO 250GB | Fractal Design Define S | Corsair HX750 | Windows 10 | Corsair M65 RGB PRO | Corsair K70 RGB LUX (CherryMX Brown) | Beyerdynamic Custom One Pro & Creative Sound Blaster Z | Nexus 6P (32GB Aluminium) | Check out my setup: Project Kalte Here!

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I don't think forward slash in this unit of measurement indicates division, it probably indicates the word "per" or "of", millimeter per water or millimeter of water. 

 

http://www.aqua-calc.com/what-is/pressure/millimeter-of-water

Thanks, that makes a lot more sense. 

Tip to those that are new on LTT forum- quote a post so that the person you are quoting gets a notification, otherwise they'll have no idea that you did. You can also use a tag such as @Ryoutarou97 (replace my username with anyone's. You should get a dropdown after you type the "@")to send a notification, but quoting is preferable.

 

Feel free to PM me about absolutely anything be it tech, math, literature, etc. I'll try my best to help. I'm currently looking for a cheap used build for around $25 to set up as a home server if anyone is selling.

 

If you are a native speaker please use proper English if you can. Punctuation, capitalization, and spelling are as important to making your message readable as proper night theme formatting is.

 

My build is fully operational, but won't be posted until after I get a GPU in it and the case arted up.

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