Positive Airflow Demonstration

darkb · Post by **darkb** » Sun Dec 21, 2008 2:28 am

Video showing the positive air pressure cooling in the SilverStone Fortress FT01 PC case with the use of a smoke machine, to make the airflow "visible".

Youtube Link

The inverted replay at the end is especially interesting.

Riffer · Post by **Riffer** » Sun Dec 21, 2008 10:51 am

I've been running with positive air pressure for years, mainly to reduce dust in the case. A few years ago, I removed the rear fan as being unecessary, so it is interesting to see that validated.

josephclemente · Post by **josephclemente** » Sun Dec 21, 2008 2:31 pm

Even though the music was horrible, I left my speakers on. There seems to be a high pressure noise as the smoke shoots out in the direction it is pointed. When the hose is placed above the case, it is pointed towards the rear exhaust, not just straight down.

I just get the impression that something isn't right about the smoke source...

Riffer · Post by **Riffer** » Sun Dec 21, 2008 7:22 pm

josephclemente wrote:Even though the music was horrible, I left my speakers on. There seems to be a high pressure noise as the smoke shoots out in the direction it is pointed. When the hose is placed above the case, it is pointed towards the rear exhaust, not just straight down.

I just get the impression that something isn't right about the smoke source...

I didn't have the sound on, but it looked like it was being blown out through the hose as opposed to being sucked in by a fan. Perhaps they felt that blowing the smoke would be an adequate simulation of a fan.

SST Guy · Post by **SST Guy** » Sun Dec 21, 2008 10:59 pm

I think you guys are reading a little too much into the details of the demonstration. The guy in the video simply doesn't have long enough arm to hold the hose directly above the top vent (and stay out of the camera view at the same time).

The air is indeed getting pushed out toward the rear at a pretty rapid rate in the FT01. If you haven't seen it, we had another video last month using a handheld windmill to show this:

http://www.youtube.com/watch?v=DLOg9yI3rjs

Olle P · Post by **Olle P** » Mon Dec 22, 2008 3:19 pm

josephclemente wrote:There seems to be a high pressure noise as the smoke shoots out in the direction it is pointed.
I just get the impression that something isn't right about the smoke source...

The hissing comes from generating the smoke with a nebulizer. Works pretty much like a high powered air brush.

The smoke isn't really "pushed" towards the case, but actually sucked in.

Riffer wrote:I didn't have the sound on, but it looked like it was being blown out through the hose as opposed to being sucked in by a fan. Perhaps they felt that blowing the smoke would be an adequate simulation of a fan.

If you look at the turbulence inside the case it's clear that a fan has moved the smoke around on its way in there.

It would be so much more interesting to see what happens when the case is placed with the rear end 3" from a wall...
My guess is that it will suffer the same problem as my computer: Some of the hot air blowing out the back is being drawn back into the top (in my case; bottom) fan.

Cheers
Olle

EarlZ · Post by **EarlZ** » Fri Jan 02, 2009 10:35 pm

Interesting, I wonder if its possible to apply this concept on a Cosmos S w/o any hard mods.

didi · Post by **didi** » Sat Jan 03, 2009 1:50 am

What point are they trying to make anyway ?
That you don't actually need a rear outtake fan ?

EarlZ · Post by **EarlZ** » Sat Jan 03, 2009 4:39 am

didi wrote:What point are they trying to make anyway ?
That you don't actually need a rear outtake fan ?

No, not really they are trying to tell us how effective positive air pressure can be.

didi · Post by **didi** » Sat Jan 03, 2009 5:22 am

EarlZ wrote:
didi wrote:What point are they trying to make anyway ?
That you don't actually need a rear outtake fan ?
No, not really they are trying to tell us how effective positive air pressure can be.

You can hardly make a point with smoke testing if you talk efficiency. What about airflow, noise, temperatures ?

EarlZ · Post by **EarlZ** » Thu Jan 08, 2009 1:14 am

I had the chance to see the case, the fans are VERY VERY noisy especially the front intake, the case is also a a tad bit pricey.

antivenom · Post by **antivenom** » Thu Jan 08, 2009 3:53 am

According to the posts in this thread, positive air pressure is good for preventing dust build up whereas a negative air pressure is better for cooling your case. But surely if the intake and exhaust were balanced, this would create a perfect balance in cooling and dust intake.

spookmineer · Post by **spookmineer** » Thu Jan 08, 2009 5:38 pm

Intake and exhaust are always balanced (after start up). The amount of air going in = amount of air going out, no matter what fans are used or where they are placed.

EarlZ · Post by **EarlZ** » Fri Jan 09, 2009 8:14 pm

spookmineer wrote:Intake and exhaust are always balanced (after start up). The amount of air going in = amount of air going out, no matter what fans are used or where they are placed.

True, but positive air pressure is all about having lesser dust in the case the area's with higher intake "rate" have dust filters as compared to a purely negative pressure that sucks in air on all possible openings.