# Testing fan blowing ability.



## i_am_pumpkin_ma (Aug 22, 2008)

Hi all, I am not too sure where to post this question, so Case mod may be the one.

Has anybody ever tested how well the fans blow air through your case, using some kind of smoke/fog, much like the way they test aerodynamics on cars?

Is there any way to do this? I am curious to see what my fans are actually doing to the air inside my case.

Any help/ideas?:4-dontkno


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## magnethead (Mar 18, 2006)

I dont think it really ever has been. I too have been interested in it.


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## i_am_pumpkin_ma (Aug 22, 2008)

Would it be a bad idea to have a lit cigarette, or something along those lines by the intake fans to see what the air does, or is that a bad idea?

I cant imagine it being a good idea, but I also cant think of how it would hurt anything either...


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## MrChooks (Apr 19, 2008)

:wave: I think you would need denser smoke than that coming off a cigarette - turbulence thru the fan/s is likely to dissipate it to a point where you wouldn't be able to see it anymore.

Way back in my early mine operations days we used to use "Draegar Smoke Tubes" (these are glass tubes that contain a white ???titanium?? salt that when exposed to air used to create a dense white smoke that we timed as it moved down a tunnel - - only used these in old workings where the air flow was very very slow - otherwise we used an anemometer). 

Anyways, check out these sites http://www.afcintl.com/kits6.htm or this one http://www.buydraegertubes.com/smoketubes.aspx

I guess the process would work - but you would need to be really sure that the "smoke residue" or anything else in the stuff didn't end up causing problems for delicate electrical connections inside your 'puter.:4-thatsba

Alternatively, maybe some chemist wizz on TSF can come up with a suitable smoke source for you.

If you do the tests - pls take some photos and post - coz I think it would be a really interesting bit of work :grin:


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## magnethead (Mar 18, 2006)

Frozen CO2? AKA dry ice?


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## MrChooks (Apr 19, 2008)

:wave: Hi Magnet - Yes might be OK and easier / cheaper than expensive smoke tubes - but you get the best results with dry ice by dropping it into a cup of water so just need to be sure that condensation / moisture wouldn't be a problem - but I guess if the 'puter is on and warm and left on and running for a while after the trials - the heat in the system should ensure any moisture vapour is removed / evaporated.

Let me know how you guys get on - am curious about this myself


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## WereBo (Apr 5, 2008)

Alternatively, a bit of corrugated cardboard rolled into a tight roll, then lit and blown out so it smoulders, should provide enough smoke. That's how the workmen tested my chimney for up-draught.


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## i_am_pumpkin_ma (Aug 22, 2008)

Werebo, I think you have the right idea with this one. Im not sure if I would trust the dry ice trick, what with the water vapor and stuff. 

But Mrchooks gave me a new thought: Smoke residue. That may be a problem...


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## MrChooks (Apr 19, 2008)

:wave: Yea Pumpkin Ma - I think smoke from burning paper / cardboard would leave black soot (carbon ! :4-thatsba) all over the place - Its OK to test a chimney - but electronics need a bit more care IMHO.

You might be able to get some useful inputs by calling Draeger direct and tell them what you want to do. I do recall that the smoke tubes we used in mines were non or low toxic (hell man I was down wind timing it).

What you need is a friend in undergraduate Mining Engineering at Uni - they might be able to "borrow" a kit from Mining School (also think the mechanical engineering faculty labs use these things for fluid dynamics (fancy words for air conditioning??) experiments / demos

Anyway - if you do these tests - pls post some pics - coz I don't think even the case makers themselves have ever bothered to do this kind of research :sigh:


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## magnethead (Mar 18, 2006)

im in mechanical/aeronautical engineering at univ texas at arlington, we have a pair of scaled wind tunnels but do not know if/how they do any smoke type tests, might be something to research


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## MrChooks (Apr 19, 2008)

:wave: hi Magnet - you are in the right place to get hold of / loan of what this kind of stuff. Does Uni Texas have a mining engineering school as that's where I would start as mining engineers (even undergrad ones, have a vested interest in looking at air flow - coz their life depends on it ) - alternatively the people in "fluid dynamics" at your Mech Engineering school will certainly know what you are looking for.

Wind tunnels used to test aerodynamics over wings tend to concentrate on looking at lift / drag issues - but if the tunnel is also used for looking at fluid flow it will almost certainly have a "smoke source"

Pls post back with how you guys get on


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## WereBo (Apr 5, 2008)

Paper/cardboard smoke is grease/oil-free (unless pre-used for chips :wink, so there'd be very little or no soot 'smuts' to stick to surfaces. Also, it's not as if it would be exposed to the smoke for hours, letting a residue build up.

For the, what, 2-3 minutes that the smoke would be blown/sucked through, it's not enough to worry about.


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## grimx133 (Jan 15, 2008)

Gotta be one of the most interesting and intriguing threads I've seen for a while. Just thinking it might be a tad difficult getting photos. Taking the side cover off would make for good visibility, but disrupt the airflow. Could try sealing the side with a piece of plexiglass, but then you'd have to cobble up things like side fans and/or vents to match the existing flow. Can see a fair bit through the side window as it is - maybe a half? Hope someone comes up with something workable, I'm right curious now.


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## magnethead (Mar 18, 2006)

i dont think mining is offered, but being we have an SAE open wheel race car, i'm willing to bet i can probe around for info within a few weeks. i know in 2 or 3 weeks we're conducting labs at the wind tunnels in our engineering lab.


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## MrChooks (Apr 19, 2008)

Yes - if the wind tunnel is being used for air flow tests over an open wheeler (hey now that would be fun for a drive!!) - then their will be a smoke stream to see the air flow. So looks like Magnet is on the job of finding out what the smoke source is.

grimx133 has a good point - and if the removable side panel could be just be temporarily replaced with a sheet of perspex / clear plastic (even if a fan has to be mounted in it) - for the tests - then should be able to see the flow.

I am really curious about where the "dead spots" are - ie those places where the airflow falls to next to zero due to differing fan placements and board / cabling obstructions.

Let us all know how you get on - coz as I posted earlier - I doubt anyone has ever looked at this issue before :4-dontkno


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## magnethead (Mar 18, 2006)

they're only small scale tunnels- i think one is 2 ft diameter the other is 3 or 4 ft, but i bet i can get us some answers.


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## magnethead (Mar 18, 2006)

just looked on google, looks like it's usually a mineral oil or other oil dripped on a heating element under pressurization to push it out the needle/probe/rod/


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## MrChooks (Apr 19, 2008)

Well done Magnet :wave: Hot / burning oil MMMmmmmm - not sure about how that would go re residue - but i am the mining Engineer - not an electronics wizz. i know for a fact that the smoke I used underground all those years ago was NOT burning oil - coz I was inspecting old working in a coal mine - and a heat source like that could have led to a monster KKAAAABANG :4-thatsba

I guess one way to check would be to see if the wind tunnel suffers any residue issues - maybe I am worrying about zip :4-dontkno because nearly all "smoke" is particulate matter - gasses are virtually all invisible - so what you see is either suspended micro particulate matter or liquid vapour.

Maybe the Draeger people have some suggestions on what would be a suitable "smoke source"

Good luck with your endeavours guys - I think this is going to be some clever research


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## i_am_pumpkin_ma (Aug 22, 2008)

I am not worried about the view, as my case has a pretty epic view inside, almost a full side. As far as dead air goes, I dont really think I have too much of a problem with that.

i have 2 intake fans in the front, side intake with epic airflow, 2 exhaust (not counting dual fans on psu). But I took the side off yesterday after I installed speedfan, and realize that my gpu is running super hot, so now I have a house fan pointed at it. Still running around 55c idle though....Ill get that figured out later.

Anywhoo, if I do get this figured out, you can expect lots of pictures, because it is a good thing to know how to do. 

Thank you for all of the responses!


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## magnethead (Mar 18, 2006)

point a 120mm fan at the gfx card, all it should need. anythign 65C or under is good for most gfx cards.


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## stressfreesoul (Mar 17, 2008)

There will definately be dead spots caused by eddies from flows of individual fans clashing with eachother. Generally, when they clash, they redirect eachother. It depends, obviously, on the strength of the each fan and their relative distances from eachother.


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## stressfreesoul (Mar 17, 2008)

I tested mine a while back, wish I'd have taken pictures now.


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## magnethead (Mar 18, 2006)

as well as voids caused by a lack of airflow, where theres no forced air nor a vacuum


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## i_am_pumpkin_ma (Aug 22, 2008)

magnethead said:


> point a 120mm fan at the gfx card, all it should need. anythign 65C or under is good for most gfx cards.


65c under stress, or idle? Speedfan gave me a flame on idle...either way, even with a big house fan pointing at it, it doesnt change much, so I am kind of curious as to how accurate the temperature is.


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## magnethead (Mar 18, 2006)

on my 9800GTX, its 65C idle and load both. If i turn my side fan up (it's on fan controller) it dropps to 62 idle and 65 load, if i turn it off, it runs about 68 idle and 78 load.


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## i_am_pumpkin_ma (Aug 22, 2008)

Thank you very much magnethead, you made me feel better knowing that somebody else with plenty of experience says its ok. I did put an extra processor fan underneath it, and put the side back on, and have a pretty steady right around 60. Good enough for me :]


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## Jtsou (Jul 13, 2007)

Interesting thread. Being a firefighter and working with smoke a lot, I may be able to do some good on this topic.


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