Positive Air Pressure?

[magellan]

+1. To add to that, air never 'goes away' like the water would in your (magellan) example, it is replaced by intake air or air from cracks, but the amount of air does not change for all intents and purposes.

So Prove it. Show me that the air pressure is above ambient.

 

[wagex]

take the side pannel off of your case and strap a box fan to it if you're that worried or have that bad of temps.

as long as you have fans blowing either air in or air out in sufficient volumes will be fine. blowing in vs blowing out is a joke i have cases in both ways all work fine. hell my mini itx machine the only air in/out fan it has is the psu fan blowing air out, and it stays perfectly cool with an i5 and 650TI i know that isnt a ton but the thing is like 8x8x11"

 

[EarthDog]

So Prove it. Show me that the air pressure is above ambient.

You prove otherwise. Can't? Me either.

And for the third time any pressure differences are MINOR there is no way I, as a general consumer, could measure them because I believe the differences are so small, but they are there.

*continues to spin tires.....dear mods, please close this inevitable ****storm that was already closed in the other monster thread... LOL!





EDIT: Let me ask you(anyone) this. WHY when there is more exhaust than intake does air come in through the cracks and into the case? WHY when there is more intake than exhaust does air come out of those same cracks in the case? What is that called? If the pressure was exactly equal between the air outside of the case and in, no air goes in or out of the case cracks right? While it may not be measurable, especially by you or I, we are seeing the signs of pressure by those characteristics, correct? Akin to knowing there is a planet we cannot see with our eyes orbiting a sun by the slight wobble of the star it is orbiting due to the planets gravitational pull (or the 'blinking' of that star when a planet we cannot see crosses its face) .

 

[RnRollie]

positive pressure test is easy... put a smokebomb in the case, and see where the smoke "leaks" out (besides the fans)

 

[Mower]

I can see positive air pressure being useful for helping dust/contaminants out.

 

[magellan]

I was thinking that there would be localized pressure spots in a case, namely where the intake fans were located and that most all of the intake air would be leaking out around these localized pressure spots. Then again, if you're pumping 50CFM, 80CFM or more into a case that has a volume of only 9 cubic feet, it seems hard to believe it wouldn't be pressurizing the case.

I had a Toyo 120 x 38 mm fan that was spec'd at over a 100CFM blowing into my old Chieftec mid-tower in the bottom front and I eventually disconnected it because it made no difference in CPU or GPU temps.

 

[EarthDog]

If you have more intake than exhaust, I would imagine in MOST areas, except those areas very close to the exhaust fans, that air would be pushing out. The same goes for the flip side. More exhaust than intake, except localized to the intake fans, air would be sucked IN to the case.


To anyone again: EDIT: Let me ask you(anyone) this. WHY when there is more exhaust than intake does air come in through the cracks and into the case? WHY when there is more intake than exhaust does air come out of those same cracks in the case? What is that called? If the pressure was exactly equal between the air outside of the case and in, no air goes in or out of the case cracks right? While it may not be measurable, especially by you or I, we are seeing the signs of pressure by those characteristics, correct? Akin to knowing there is a planet we cannot see with our eyes orbiting a sun by the slight wobble of the star it is orbiting due to the planets gravitational pull (or the 'blinking' of that star when a planet we cannot see crosses its face) .

 

[magellan]

You prove otherwise. Can't? Me either.

Would a simple barometer work? It's calibrated to work around STP.

I wonder if a cylinder leak down tester wouldn't work?

If you have a transparent side cover you could observe the measurements in either case.

 

[EarthDog]

A simple barometer is not granular enough I wouldn't think(?). Depends on what it can read. Are tenths/hundreths of a mb enough? Who knows!

A cylinder leakdown tester wouldnt be granular enough for sure... unless there are new ones out that are more granular than mb.

 

[Soulcatcher668]

I had a Toyo 120 x 38 mm fan that was spec'd at over a 100CFM blowing into my old Chieftec mid-tower in the bottom front and I eventually disconnected it because it made no difference in CPU or GPU temps.

I think this is where you are getting confused.

The pressure differentials that we are talking about are very small. Thus there is no coloration between pressure and temperatures.

Good airflow is much more important than pressure.

In fact the more positive or negative pressure you have, the worse your airflow is.

 

[ShrimpBrime]

Oxygen needs to be compressed into a sealed container via pump in order to be considered pressurized.

The simplest way to create more positive pressure would be to have no exhaust fans and only intake fans, thus creating a pressure. That pressure will lower when you turn exhaust fans on or have holes.

If there are enough holes for the amount of air being pushed into the case to be dissipated at that point in time, you will have only air flow, not pressure.

The best way to create pressure in your case is to seal it completely and leave a single 120mm hole for exhaust and have 4 120mm intake fans. You would have a large amount of air flow trying to escape from the 120mm and thus create a case pressure.

This concept does not have any effect on ambient temps therefore is a waste of time for concern.

Now if you could create a pressure and release it onto a heatsink vs releasing it out of the case, you could accommodate the pressure to make a larger airflow or cfm to the cooling device surface area by using multiple fans and only one exhaust.

Other than that, more or less fans by one or two will probably make a ****s bit of difference calling it a pressure when the pressure and higher air flow exhaust isn't being released onto anything that needs cooling.

 

[Soulcatcher668]

If there are enough holes for the amount of air being pushed into the case to be dissipated at that point in time, you will have only air flow, not pressure.

I'm going to try this one more time and then I am out.

Pressure differential creates airflow.
Pressure differential is the only reason air moves at all.

A fan creates a pressure differential.
That pressure wants to equalize itself (move to a lower pressure area). Any body that gets in the way (your computer case in this case) creates resistance to that.

 

[Tweaked1024]

Wow quite a topic here. I have worked on class 1 clean rooms. The only thing that really mattered was that contaminates stayed out. Done with positive air pressure, mass amounts of filters and a great deal of havoc expense. With regards to my PC case, airflow and dust containment. Ideally, the air would go in one spot and out the rest. One filter to change. Easy peasy to feel at the cracks. Or use a lighter like I do at my house windows. In the end, do proper maintenance and it really don't matter. As for measuring it, omg way too much work.

 

[Tweaked1024]

Ohh and it's called a magnehelic and the units are inches of water.

 

[magellan]

I think this is where you are getting confused.

The pressure differentials that we are talking about are very small. Thus there is no coloration between pressure and temperatures.

Good airflow is much more important than pressure.

In fact the more positive or negative pressure you have, the worse your airflow is.

I figured my 120 x 38mm high speed, 100CFM, toyo fan would at least make a diff in GPU temps, because it was blowing right at the end of the video card (maybe an inch away), but it never did, it just made noise. Maybe because there was too much restriction on the intake side (it was filtered and went through a grill that was much smaller than the 120mm fan).

I know ED doesn't like to hear about rack mount servers, but if you look at his picture you can see the baffles that direct all the airflow through the CPU's heatsink assembly and the DIMM's. The fans in the IBM x3550's I'm familiar with run at 6000RPM, so I bet they have high airflow, high static pressure and lots of sound pressure.

Intel wrote a white paper from 2008 called Thermally Advantaged Chassis,
it suggested a design that featured only three fans and a single intake vent of a particular size and placement. The fans were a PSU fan, CPU heatsink fan and one exhaust fan. Case pressurization isn't brought up in the white paper but airflow was.

 

[ShrimpBrime]

I'm going to try this one more time and then I am out.

Pressure differential creates airflow.
Pressure differential is the only reason air moves at all.

A fan creates a pressure differential.
That pressure wants to equalize itself (move to a lower pressure area). Any body that gets in the way (your computer case in this case) creates resistance to that.

Ohh and it's called a magnehelic

Put your little magnehelic and pressure differential where my case and rad fan sun doesn't shine.

You guys don't even "know" what pressure is yet with your little 120mm fans doin' a lousy 80cfm-110cfm range most likely, on top of that on a fan controller in fear of noise while gaming with headphones on.

And the red stuff on it is partially from a cat, and the other from people that think they know their cooling and got their hand and magnehelic too close.

Cool your house with muh set up son.

Parity post only half true. The blood is untrue. The usage and cooling ability is true.

Freekin case pressure threads. I love em'

 

[Soulcatcher668]

You have moved the goal posts Magellan.

The only time that positive or negative pressure would have anything to do with cooling is if it was woefully one sided (all fans blowing in or out).

Positive or negative pressure is only relevant when you are talking about dust.

Airflow is key. The more air that is passing a heat sink and then being exhausted from the case the better.

It does not matter how many fans you have in the case (your 100CFM fan 1" from the GPU) if the hot air is not leaving.

When I first built my current rig, I had a 7970 DCII that overheated because I had a dead zone of air. The cooler on that card is great, but if you cannot get fresh air to it, no cooler in the world will make a difference.


ShrimpBrine.... This is why these threads get derailed. .001 PSI and 5000PSI is still a pressure differential. The size of your fan does not change the science behind it.

 

[Luke1978]

Reading through threads like this never gets old....

On a side note, and its a negligible side not albeit. To much one way or the other stresses and shortens the life of your fans. Not enough incoming air makes your exhaust fans struggle to pull the air from those cracks, and therefore loses efficiency. Not enough air being forced out has the same effect.

Want to see a good example go start your car and turn the heat or AC on high with all the windows up and doors closed, then roll a window down. Subwoofer in a bandpass box has a similar effect.

Like I said the difference is negligible, and the stress is probably insignificant. Otherwise da fuq does it matter? This argument is as old as computer cases.

 

[Tweaked1024]

Airflow requirement means that the environment inside the case does not continue to increase in temperature up to the btu output of the devices enclosed....is that right? out with the warm and in with the less warm. hmmm... how about if the air outside the case is higher in temp than the air inside the case, you want positive air pressure, and if the temp outside the case is lower in temp than the temp inside the case, then you want negative air pressure...hmm, wait positive air pressure means that the air inside the case is recirculating and rising in temp before it can leave the case. darn, ok but a photon takes millions of years to leave the center of the sun and its temp will only reach the btu of the sun before it leaves...hmm ahh frig it, airflow.....smairflow...if I hear fans, air is going in, and air is coming out...all good!

hey man, that's a Blower not a Fan...it don't count...hehe

 

[EarthDog]

I figured my 120 x 38mm high speed, 100CFM, toyo fan would at least make a diff in GPU temps, because it was blowing right at the end of the video card (maybe an inch away), but it never did, it just made noise. Maybe because there was too much restriction on the intake side (it was filtered and went through a grill that was much smaller than the 120mm fan).

I know ED doesn't like to hear about rack mount servers, but if you look at his picture you can see the baffles that direct all the airflow through the CPU's heatsink assembly and the DIMM's. The fans in the IBM x3550's I'm familiar with run at 6000RPM, so I bet they have high airflow, high static pressure and lots of sound pressure.

Intel wrote a white paper from 2008 called Thermally Advantaged Chassis,
it suggested a design that featured only three fans and a single intake vent of a particular size and placement. The fans were a PSU fan, CPU heatsink fan and one exhaust fan. Case pressurization isn't brought up in the white paper but airflow was.

I don't like the mention of servers for the previous mentioned reason of the case not being remotely like ours. Pressure isn't mentioned because, like I have been saying the entire time its negligible.

Ahh forget it. Tberr was a reason a 487 post thread existed on this subject with no real answers... And as alluded to in my first post.. here we go again. I'm off this thread boys. Have fun spinning your wheels.