# Static pressure vs. airflow fans



## KHIT (Dec 28, 2012)

Hi
I'm currently looking at getting a fan for the front of my NZXT Phantom(Original) and I'm wondering if a static pressure or a airflow fan would suit my system best. I'm looking at getting some CORSAIR AF or SP series fan as I've heard a lot of possitive response to these fans. Are there any quiet fans in either 120mm or 140mm you can recommend other than the ones from corsair. Would Noctua be a better choice? And last but not least, should I use pressure or airflow fans for the front?


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## phoen (Dec 28, 2012)

For case fans you need good airflow, static pressure fans is for heatsink/rad.


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## Bo$$ (Dec 28, 2012)

140mm are generally quieter as they spin more slowly


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## Jack1n (Dec 28, 2012)

Is it the lower front fan that blows air on the hard drives?,if so it might be better to get static pressure because your drive bay is pretty populated.


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## qubit (Dec 28, 2012)

KHIT said:


> Hi
> I'm currently looking at getting a fan for the front of my NZXT Phantom(Original) and I'm wondering if a static pressure or a airflow fan would suit my system best. I'm looking at getting some CORSAIR AF or SP series fan as I've heard a lot of possitive response to these fans. Are there any quiet fans in either 120mm or 140mm you can recommend other than the ones from corsair. Would Noctua be a better choice? And last but not least, should I use pressure or airflow fans for the front?



You're confusing terms here.

There's no difference between static pressure, pressure or air flow.

All fans work the same way and generate air pressure by moving air ie air flow.

All you're interested in is how much air flow the fan generates at what noise level. Generally, people like quiet fans so that means the largest fan that you can get, made by a good quality manufacturer such as Noctua etc.


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## de.das.dude (Dec 28, 2012)

^ you high?

more static pressure fans = better suited for heatsinks and radiators, and things that usually offer a lot of resistance to the fans.


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## Jack1n (Dec 28, 2012)

de.das.dude said:


> ^ you high?
> 
> more static pressure fans = better suited for heatsinks and radiators, and things that usually offer a lot of resistance to the fans.



Such as an HDD cage with 3 HDD's in it.


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## RejZoR (Dec 28, 2012)

qubit said:


> You're confusing terms here.
> 
> There's no difference between static pressure, pressure or air flow.
> 
> ...



Erm, no? You need static pressure when you have to push a lot of air through tight space like heatsink or water cooler radiator. Air flow is needed when you just need to push a lot of unrestricted air.

Be aware that air essentially behaves like liquid. Without pressure, it will slow down significantly through tight spaces.


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## KHIT (Dec 28, 2012)

Thanks for your replies. I want a fan for the front of the case. The one that is not included with the case.
so this means that a static pressure fan is the one


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## erocker (Dec 28, 2012)

KHIT said:


> Thanks for your replies. I want a fan for the front of the case. The one that is not included with the case.
> so this means that a static pressure fan is the one



No, it would mean that you want the airflow version. The static pressure fans are for radiators and heatsinks.


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## n3rdf1ght3r (Dec 28, 2012)

The 140mm would be quieter than the 120mm because it can spin at a lower RPM but still push the same amount of air. You would normally use an airflow optimised fan for the front of a case but if you happen to have alot of hard drives, you might want to go towards a pressure optimized fan. Noctua's are great fans and very silent. If you are going for the corsairs, I would recommend the quiet editions because a properly optimized gaming rig should be silent.


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## MxPhenom 216 (Dec 28, 2012)

qubit said:


> You're confusing terms here.
> 
> There's no difference between static pressure, pressure or air flow.
> 
> ...



    

Is all i have to say about that statement. LOL


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## erixx (Dec 28, 2012)

Reminds me discussions about what is better, if torque or horsepowser, or twins/inlines in motorcycle forums (and who knows, even cage forums...


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## D4S4 (Dec 28, 2012)

very similar to tq/hp, i'm amazed so many people still don't know rpm*tq=hp.

anyhow, common sense ftw - you have a tight case grill with small drilled holes, use high static pressure fan. you have a wide spaced case grill (or you can cut it out completely), use high flow fan.


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## phanbuey (Dec 28, 2012)

Intake fans, rad fans, and heatsink fans should have good static pressure, exhaust fans can sacrifice a bit for airflow, especially in a positive pressure case (where you have more intake than exhaust).


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## qubit (Dec 29, 2012)

MxPhenom 216 said:


> Is all i have to say about that statement. LOL



 to you too and the rest of you numpties taking potshots at me. 

More airflow gives you more pressure. End. You so-called experts should understand this.


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## Peter1986C (Dec 29, 2012)

Much air flowing trough large spaces: high flow & low pressure.
Much air flowing through small(er) spaces: high flow & high pressure.

Air flow is the gaseous equivalent to the ampère and (static) pressure is the equivalent to the Volt. One could also compare the matter to water (or any other fluid) going trough a wide versus narrow tube.

Please correct me if I am wrong, physics class is too long ago for me as it seems.


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## erixx (Dec 29, 2012)

that is all right and nice, but the difference that matters is that the high pressure fan is just a better (aka stronger) fan that maintains its air productions even if there are obstacles. The high speed fan is supposed to loose it's speed in adversity...

Feel free to correct me...


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## sneekypeet (Dec 29, 2012)

erixx said:


> that is all right and nice, but the difference that matters is that the high pressure fan is just a better (aka stronger) fan that maintains its air productions even if there are obstacles. The high speed fan is supposed to loose it's speed in adversity...
> 
> Feel free to correct me...



That's the way it works. High flow does not equal high pressure.


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## qubit (Dec 29, 2012)

sneekypeet said:


> That's the way it works. High flow does not equal high pressure.



It's ultimately the speed of the air that creates the pressure, which is all I'm saying and people don't seem to understand. Hence, the faster the air goes, the more pressure, regardless of fan size. A bigger fan simply moves more air.

Also, asking for a "static pressure" fan like the OP does is nonesensical and I tried to expain this to him, as everyone gets confused otherwise, especially him. It's as dumb as asking for a car with "speed". They've all got it, or they wouldn't go anywhere! The real question is whether one should buy a fast car or a slow car and the tradeoffs between them. Same with the pressure rating of a fan.


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## sneekypeet (Dec 29, 2012)

Explain a Noctua fan to me then! They break you rule of speed = pressure, because they are one of the lowest in speed, but averagely highest in static pressure.

You need to understand that a lot of high speed fans, once impeded, dont have the pressure needed to force the air around or through the obstruction, even if the RPM still says 2000, you aren't getting the full air flow or static pressure in the average fan. Fans with Static pressure have the "torque/ass" it needs to keep supplying close to the same CFM and air flow specs, even when impeded upon


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## qubit (Dec 29, 2012)

sneekypeet said:


> Explain a Noctua fan to me then! They break you rule of speed = pressure, because they are one of the lowest in speed, but averagely highest in static pressure.



The angle of the fan blades, their overall design and how close they are to the outer casing without touching it greatly affects the efficiency of a fan. Hence, if you compared the best fan with the poorest at the same revs using an air flow meter you would see the air move faster with the better fan (and likely with less buzzing, whining or other unpleasant noises, too). It therefore would have higher pressure/static pressure (same thing).


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## sneekypeet (Dec 29, 2012)

I think you need to get an airflow meter, and set up a tube full of water to comprehend what I am saying. What I am saying is the truth, I have no reason to BS you! 

All I am stating is that while your analogies may make sense, when you test these fans appropriately, fans with high static pressure ratings tend to keep that mark. Those geared for higher RPM with a low static pressure rating are going to lose both air flow and pressure as you add things in front of it (such as that tube of water).


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## erocker (Dec 29, 2012)

qubit said:


> The angle of the fan blades, their overall design and how close they are to the outer casing without touching it greatly affects the efficiency of a fan. Hence, if you compared the best fan with the poorest at the same revs using an air flow meter you would see the air move faster with the better fan. It therefore would have higher pressure/static pressure (same thing).



You're forgetting the motor and how resistance plays a part in its performance.

Example: a weaker motor that spins fast can produce a lot of airflow. Impede the airflow by placing a radiator in front of the the weaker motor will not work very well. A more powerful motor will not be hindered so much by resistance resulting in higher airflow during situations where higher static pressure is needed.


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## sneekypeet (Dec 29, 2012)

bearings, bushings, pitch, angle, shape, texture, additional features in a frame such as dimples or step down areas where the air first rubs against the frame, there are literally tons of ways to change the performance of a fan. 

All I am getting at is that there are high static pressure fans for a reason, it isn't just a marketing gimmick as Qubit is implying.


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## qubit (Dec 29, 2012)

sneekypeet said:


> I think you need to get an airflow meter, and set up a tube full of water to comprehend what I am saying. What I am saying is the truth, I have no reason to BS you!
> 
> All I am stating is that while your analogies may make sense, when you test these fans appropriately, fans with high static pressure ratings tend to keep that mark. Those geared for higher RPM with a low static pressure rating are going to lose both air flow and pressure as you add things in front of it (such as that tube of water).



I never thought for a moment you were BSing me! 

It sounds like what you're talking about is the motor quality that erocker mentioned, below. Yup, a high torque motor will help to keep the fan speed up all right against resistance, without adding more voltage and is another important quality metric. I'd forgotten about it, so shoot me. 



erocker said:


> You're forgetting the motor and how resistance plays a part in its performance.
> 
> Example: a weaker motor that spins fast can produce a lot of airflow. Impede the airflow by placing a radiator in front of the the weaker motor will not work very well. A more powerful motor will not be hindered so much by resistance resulting in higher airflow during situations where higher static pressure is needed.



Indeed, as to sneeky above. 



sneekypeet said:


> bearings, bushings, pitch, angle, shape, texture, additional features in a frame such as dimples or step down areas where the air first rubs against the frame, there are literally tons of ways to change the performance of a fan.
> 
> All I am getting at is that there are high static pressure fans for a reason, it isn't just a marketing gimmick as Qubit is implying.



I never said there was any marketing gimmick here?  And the dimples etc are the differences I'm talking about when comparing the quality of fans. The better fan will move the air faster at a certain revs than the poorer one and push back harder against air resistance in front of it, maintaining its speed better.


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## MxPhenom 216 (Dec 29, 2012)

Typically fans that have less blades usually have blades that a larger and at specific angle, and a strong motor. These fans have more static pressure, hense why they are used so much more for pushing air through heatsinks and radiators, and sometimes front hard drive bays. Fans specifically meant for case fans and supplying airflow have a lot more blades. Take a look at the difference between the Corsair AF120 and SP120s. The blades are different, and the SP120s are stronger since they are meant to push air through things.

They don't have a static pressure spec in the spec table for fans for nothing.


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## qubit (Dec 29, 2012)

MxPhenom 216 said:


> Typically fans that have less blades usually have blades that a larger and at specific angle, and a strong motor. These fans have more static pressure, hense why they are used so much more for pushing air through heatsinks and radiators, and sometimes front hard drive bays. Fans specifically meant for case fans and supplying airflow have a lot more blades. Take a look at the difference between the Corsair AF120 and SP120s. The blades are different, and the SP120s are stronger since they are meant to push air through things.
> 
> They don't have a static pressure spec in the spec table for fans for nothing.



So at the same revs, those fans will move the air faster, hence giving you more pressure. Alternatively, they spin the blades real fast, to get the air speed up, like the noisy Deltas. It's quite simple and that's all I'm saying.

Dunno why people are making such a meal out of this, including you with your inappropriate snidy remark to me before.  You really should apologize for it.


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## MT Alex (Dec 29, 2012)

qubit said:


> Dunno why people are making such a meal out of this, including you with your inappropriate snidy remark to me before.  You really should apologize for it.



Nevermind.


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## Jetster (Dec 29, 2012)

Static pressure vs. airflow fans

All fans are both. Static and CFM is a measurement

So am I the only one confused by this question


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## MxPhenom 216 (Dec 29, 2012)

I don't need to apologize for anything.


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## qubit (Dec 29, 2012)

MxPhenom 216 said:


> I don't need to apologize for anything.



Yeah, you do. You're not man enough of course, but that still doesn't stop me putting you in your place with a suitably condescending post on you being such a d*ck with that dumb personal attack.


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## sneekypeet (Dec 29, 2012)

Jetster said:


> Static pressure vs. airflow fans
> 
> All fans are both. Static and CFM is a measurement
> 
> So am I the only one confused by this question



Read the OP, he clearly states he is looking at the new Corsair fans, and if you look at the series names they are set in those two groupings

So we went from Qubit being mad about smileys and wanting an apology, and then Qubit dives into an infraction-able offense of then calling him names? Qubit, I think you need to relax a bit man. Since I don't edit this section, the infraction is not mine to give, but as I sit here, you now owe him an apology.


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## qubit (Dec 29, 2012)

I was personally attacked first after trying to help the OP - by several people - and nothing was done about that by the mods. So why should I apologize for standing up to a bully?

Even if my first post had been completely wrong on technical merit (it wasn't, at all) it doesn't give people the right to behave like jerks and then get away with it, does it?


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## sneekypeet (Dec 29, 2012)

I don't see how emote icons and some sarcasm got you in such a tight bind, but as for now I think you should walk away, and not accuse me now of standing up for a "bully", as I personally don't care if either of you are butthurt unless it breaks the rules, which you did!


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## qubit (Dec 29, 2012)

Whatever. Not giving a damn is fairly typical of TPU management nowadays.

Read over those posts - you telling me the others didn't break the rules?


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## Athlon2K15 (Dec 29, 2012)

WALK AWAY JESUS CHRIST MAN!


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## qubit (Dec 29, 2012)

AthlonX2 said:


> WALK AWAY JESUS CHRIST MAN!



I have, thanks man. 

EDIT: I was confused once myself about what was meant by pressure and static pressure. Wikipedia soon came to the rescue, explaining how they're the same, here.  This is the relevant paragraph:



> Static pressure in fluid statics
> 
> The term static pressure is sometimes used in fluid statics to refer to the pressure of a fluid at a nominated depth in the fluid. In fluid statics the fluid is stationary everywhere and the concepts of dynamic pressure and total pressure are not applicable. Consequently there is little risk of ambiguity in using the term pressure, but some authors[17] choose to use static pressure in some situations.


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## MxPhenom 216 (Dec 29, 2012)

qubit said:


> Yeah, you do. You're not man enough of course, but that still doesn't stop me putting you in your place with a suitably condescending post on you being such a d*ck with that dumb personal attack.



You sound mad bro....Calm down its just the internet.


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## sneekypeet (Dec 29, 2012)

qubit said:


> I have, thanks man.
> 
> EDIT: I was confused once myself about what was meant by pressure and static pressure. Wikipedia soon came to the rescue, explaining how they're the same, here.  This is the relevant paragraph:



That quote says that pressure = static pressure, that's a no brainer. You initially stated airflow = static pressure, which it does not, so what is the point of the wiki link?


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## qubit (Dec 29, 2012)

MxPhenom 216 said:


> You sound mad bro....Calm down its just the internet.



I don't like you any more.   Cheers matey.

EDIT:



sneekypeet said:


> That quote says that pressure = static pressure, that's a no brainer. You initially stated airflow = static pressure, which it does not, so what is the point of the wiki link?



Just to clarify those pressure/static pressure terms for anyone wondering about it like I did a while back and add a bit of useful knowledge. Nothing more or less.


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## Tatty_One (Dec 29, 2012)

qubit said:


> Whatever. Not giving a damn is fairly typical of TPU management nowadays.
> 
> Read over those posts - you telling me the others didn't break the rules?



Sorry you feel that way, in my experience, people that think this are usually on the receiving end of some flak, from what I have read in these posts, you started with an honest opinion with honest advice, you got some of it factually incorrect, or perhaps just got confused (I did too!) you were challenged on some of it, you then lashed out, got some back and now the community is poorly managed and your left feeling bullied and hurt.... have I got that about right?  

You know better than most.... just report what offends you, don't react to it, that way we keep it impersonal and allow those who's job it is to moderate to do just that.... end of speech.

Thread going nowhere now and closed.


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