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Is Positive Pressure As Simple As Adding Up CFM?

Draekhost

56 months ago

Hello!

Along the whole Positive, Neutral, Negative pressure idea for case airflow, is determining positive pressure as simple as adding up the CFM of all inward facing fans, and measuring it against the CFM of all outward facing fans?

I want a bit of positive pressure going on, and I have the following fans going on:

Inward facing - 1 x 200mm fan pushing up to 110.1 CFM 2 x 120mm fans pushing up to 69 CFM

Outward facing - 1 x 140mm fan pushing up to 82.1 CFM 2 x 120mm fans pushing up to 69 CFM

I know there are other factors like screens/vents/dust collectors, but based on the fans mentioned above and assuming they are all controlled by the same controller, is it safe to assume positive pressure is achieved?

If not, can you guide me a bit on how I can make sure there is positive pressure without putting strain on anything?

Thank you for your time!

Comments

  • 56 months ago
  • 2 points

Another issue is actual flow. It doesn't matter if you have a fan that's doing 10,000 cfm's if it's trying to draw it through the eye of a needle. So it depends on the grills and air intakes of the case.

That said, the Enthoo's have a great rep for airflow so you don't need to worry.

[comment deleted]
  • 56 months ago
  • 1 point

I like intook! And awesome, just wanted to make sure.

I'm using the Enthoo Pro by Phanteks and they have a mostly meshed case, but there are small holes along the edge of the case that allow for dust to get in. I figured positive pressure was the easiest way to make it a non issue, along with maybe some custom mesh being glued on the inside to make it all meshy (meshified?).

  • 56 months ago
  • 1 point

One more question:

Since I have an assortment of fans to choose from, I could take that 200mm and point it outward on the top of the case for this kind of setup:

Inward facing fans: 4 x 120mm 69CFM fans

Outward facing fans: 1 x 200mm 110.1 CFM fan 1 x 140mm 82.1 CFM fan

Am I potentially straining all those inward facing fans with this much difference in air pressure?

  • 56 months ago
  • 2 points

What strain? That's ~276 CFM in, ~192 CFM out (at full speed).

  • 56 months ago
  • 1 point

The strain of the inward fans, pushing so much air while possibly not having the room to allow all that to flow outside of the case easily?

I'm not sure. I might be over thinking the actual "pressure" building up from positive pressure. It just came to mind since there'd be so much power going inward and only a little going outward, I'd wonder if this would strain the inward facing fans due to all the extra inward airflow building up somehow in the case.

I guess with the amount of escape potential on the site of this case I won't really need to worry about it. Plus, it's air, so it's not like the pressure lasts. Don't mind me. I'm just new at this :P

  • 56 months ago
  • 2 points

Yea, you shouldn't really need to worry about it. There are some cases where I would worry about it, but that's with some insane fans (like this one) where you're seeing massive CFM.

[comment deleted]
  • 56 months ago
  • 1 point

agreed... I would only recommend positive pressure on cases like the RVZ01 which are meant for it because of the reduce space and small amount of fans.

  • 56 months ago
  • 1 point

Alright. In that 2nd configuration, I'd have 4 fans on the front (2 on actual front and 2 on bottom front-ish), 1 fan on the back going outward, and another on the top going outward. I'll play around with it and see what works best.

  • 56 months ago
  • 1 point

Took in? Taken in? I'm a grammar nazi myself, but that's a hard one to figure out. Don't forget to mention that rated CFM isn't necessarily reliable, because there is standard way of measuring it.

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