Blowers vs. axial fans

[n8x2]

I've been reading about a lot of peoples experience with blowers lately and realised I didn't know how to compare it with an axial fan that was approx. the same size and noise level.

I checked out a bunch of manufactures spec's on various models, and noticed a trend:

Sunon Example:
(I picked fans from the same manufacturer, hoping that their potentially scewed spec's are scewed equally, so that they can be compared)

Type.....Size.........Part #....................dBA.......RPM......CFM......"H20
Axial.....120x38.....KD1212PMBX-6A.......46.5......3150.....120.......0.34
Blower...120x32.....PMB1212PLB3-A.......49.6......2100.....31.4......0.64

Both: 12V, dual bearing
Note: @ almost 50 dBA, I am not planning on running either of these at 12V! These fans just illustrate the trend I've been seeing.

Obviously, the blower fan will produce a more concentrated and easily 'ductable' airflow, simply because of the way the device operates. The axial will produce more of a 'hurricane' air flow.

There is also the HUGE difference in air flow and static pressure, with the axial's airflow a whopping 4X that of the blower, but the blower's static pressure double that of the axial.

Conclusions:

So in an open air environment (such as a case fan in a reasonably tidey case), the axial is the better choice: large hurricane airflow throws air everywhere and a much higher total airflow. Sound about right?

But what about pushing (or pulling) air through an obstruction such as a heatsink? The blowers uniform, ductable airflow has got to be better than the hurricane (with that funderwul deanzone behind the hub!!) of the axial. And does a typical large HS constrict airflow enough such that the blowers superior static pressure comes into play, and actually creates a higher air flow, in this situation? Or does the sheer air flow capacity of the axial (assuming it's ducted to the HS) still beat out the blower with HS type obstructions?

Thoughts, comments, suggestions? (other than to spend less time thinking about airflow!! )

N8

 

[CrashOveride]

i think thats why we use em

lol good info though, i never really thought about that...

i do think that a blower might give more consistant preformace with backpreassure caused by a HS or somthing... but i dont think it would be enough to make it worth it

 

[cV]

The main thing keeping me away from blowers is the annoyance factor, because the blades are so small. They need to make an uber-blower water wheel type blower and adapt it to 92mm mounts for the slk-900.

 

[modenaf1]

so for a heatsink, one would want higher pressure? is that why a smt fan2 pushes about the same amount of air as a tornado, but dosent do as good, bercause of the pressure?

 

[CrashOveride]

so for a heatsink, one would want higher pressure? is that why a smt fan2 pushes about the same amount of air as a tornado, but dosent do as good, bercause of the pressure?

ya you would want good pressure- think about it, you dont want all your air coming back out of hte fan (backwards) do you? that wot cool well-, and that is probablyt why...

 

[modenaf1]

thanks crash.

what exactly are blowers? anyone have a linky?

i think i might have one on my dell dim 4300s

 

[huneycutt]

Not that much of a difference.

I put one in and the temp decrease inside the case was not worthy of note. (I know how to take internal readings with a mercury thermometer, ambient temp taken into consideration.) I think it's beause the cool air is at the bottom, hot air at the case top and the blower mounts at the bottom.

An 80mm case fan mounted at the top or middle of the case and rated at 20-25 Decibles is quiet and moves about 30 CFM. This takes a bunch of hot air out and will do you a good job. I thought the blower much noisier than the case fan.

They can tell me anything they want, but when I look at the mercury thermometer it removes all guess work. Facts is facts.
Old Bird

 

[Yuriman]

The GeforceFX has a blower of sorts, if that helps, moderna.

 

[huneycutt]

Blowers

I looked at mine, AOC System Blower FC-2000. Granted, it is an impressive looking gizmo and it does move a heck of a lot of air, but as I said, didn't make an impression on me or the thermometer.

http://www.nexfan.com/tucafan804.html Quiet case fans are a buck and if you're willing to put up with the noise go for for a high speed one. Nexfan also has the round IDE cables on sale for like $2.50 each. Very economical place to shop, I surf in there every week and have ordered from them five times, good people.

Let's not overlook the dual fan PSU whereby the one fan draws heat in from the case, blows it through the PSU, then the other fan exausts it. I run a dual fan Enermax and you can feel the heat pouring out, almost like a second case fan. Do the math, with one 30CFM case fan and the 30CFM PSU exaust fan I'm moving 60 CFM of air through my computer, SIXTY cubic feet a minute.

Another solution to this case cooling thing is take the side off or leave it open about four inches. It might introduce a bit more dust inside, but we enjoy cleaning our computers house anyway, right? Leaving the case open somewhat defeats the case fans pulling air in through the vents. If I take the side off I immediately notice a two to five degree drop in the CPU temp, but it's not worth it to me. You can get a cutter and make a hole in the side and put another fan in there, but is it worth the hassel?

Bottom line, the important thing is your CPU stay within temp tolerances and if your CPU temp monitoring utility tells you the temp is OK you should be good to go.
OldBird

 

[modenaf1]

yep. I have a blower on my P4 dell. it pulls air onto the hs and pushes it through the back.

thanx.

 

[huneycutt]

Blower

I had a Dell OptiPlex and it had a regular CPU heat sink fan with the plastic shroud that takes the hot air out the back. It was not a blower. Looky here: http://www.directron.com/fc2000b.html
That's a blower.