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How much do wire mesh filters impede airflow?

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Nagorak

Senior Member
Joined
Dec 19, 2000
Recently I decided to upgrade my computer after a long period and while I was at it, I thought I would revisit my cooling setup. I have always been a little concerned that my case might have negative air pressure, and with some of the newer graphics cards it appears that they exhaust outside of the case, so that only makes things worse.

I would definitely prefer a case with positive pressure and this is initially how I set-up my computer. My concern is my intake fans all have filters which cutdown on airflow. So, even if the rated air intake is higher the actual air intake may be a lower rate, thus negative air pressure.

Does anyone have any idea how much the average wire mesh filter cuts down on air flow? I would guess it must be a significant amount, so I would appreciate any rules of thumb or links to guides on this topic.
 
you mean filters like this? Yes, they restrict airflow A LOT. So if you will be using them, make sure you have at least 50cfm to push through it, and just make sure your parts dont get too hot. I mean...these filters are only needed for intake holes, so make sure the exhaust ones are free from obstruction and have optimal airflow to compensate for the blocked intake.
 
enz660 said:
you mean filters like this? Yes, they restrict airflow A LOT. So if you will be using them, make sure you have at least 50cfm to push through it, and just make sure your parts dont get too hot. I mean...these filters are only needed for intake holes, so make sure the exhaust ones are free from obstruction and have optimal airflow to compensate for the blocked intake.

Yeah like that. I have a lot more than 50 CFM. I am just trying to figure out how much more input I should have than output to make up for it (the outputs don't have filters so they aren't reduced). My case ventillation is pretty good and I've never had problems with heat (temps are lower with case closed). I'm just unhappy potentially having negative pressure.

Going without the filters just isn't an option because I know within a few weeks the inside of my case would be caked with dust. It's too much trouble to have to constantly clean everything off including the CPU heatsink and fan.
 
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How about intercepting most of that dust before it gets to your computer...get a good room air cleaner/purifier that uses the Hepa air filter system...it will be better for the people in the room and will be better for your computer. Then, with some good grills/filters on the intake fans, the amount of dust that gets into the case will be minimum and will require a lot less maintenance.
 
I appreciate the suggestions guys, but I'm really just looking for some information. :)

I live in a household with lots of animals, so unfortunately the fan filters on the intakes aren't optional. I guess when I say I'm concerned about dust, I'm really mostly concerned about fur. The animals are constantly shedding and no matter how hard you try to keep it swept up, you'll never manage to get it all.

Anyway, what I was hoping was that someone knew what percentage of CFM the wire filters cut back on. So, for example, if I knew the filters reduced CFM by 33% I could plan on having say 100 CFM going in, but only 65 CFM going out and thus balance the flow and still have positive pressure.

Maybe I am just worrying too much about this though because, to be honest, I haven't really had serious problems in the past. I have sealed all of the other intake areas so really not much air can come in and if it does it can't bring fur with it. So, maybe I am just being silly, but I was curious if anyone had any hard info on how much the filters reduced air flow. ;)
 
Nagorak...you are worrying too much about negative versus positive air flow....it's just not that big of a deal. But animal fur getting into the case IS a big deal..it can do a lot of damage. You said that .."fan filters on the intakes aren't optional". I will politely say that in your situation that fan filters are ABSOLUTELY NECESSARY! How else do you plan on keeping your computer from overheating from hair build up...possibly shorting out components. Can you afford to buy new components every few months?

If you open your case every week or two and thoroughly clean out the hair...that would work...but wouldn't that get rather frustrating after a while?

As I mentioned before...why not have a room air filter that will get most of the animal hair...not all...but most.

Another way to go would be to get some very high cfm fans and then with fan filters there would still be plenty of air getting through...but at the expense of a lot of noise. Personally, I don't like a noisy computer, but you may be different...that would be your call on that.

What are your temps?

As far as negative versus positive pressures, the generally recommendation is to have a balance between air coming in and air going out. The main concern is that the components are getting adequate air circulation and that there is a good directional air flow into and then out of the case.
 
I got 4 of these in the mail last night. I hooked up a Yate Loon to an extra PSU hotwired and moved the filter on and off the fan and well they suck. I will not be installing them as they cut air flow to almost nothing. I will just blow out my case once a month.
 
The better job it does of collecting dust/debris the more restrictive it is on air flow (general rule). You need to decide how much dust/debris you can put up with inside your case then find a grill to match it.

I use my wire mesh grills for show and to keep fingers out. It's not very restrictive, does catch some dust and looks good.
 
Immortal_Hero....I have one of those grill/filters coming my way and I was also wondering about just how much air flow they restricted...hmmm...what cfm rating are your Loons? I'll just have to see how my S-Flex fans react.

There are a couple of more options...1. Get some of that foam material that is used for window ac filters...it's not very restrictive and would catch a lot of dust....2. Use either a used or even new dryer softener sheet...it is also not highly restrictive ( at least the used sheets, haven't tried a new sheet). I actually have a used sheet that I have for my side intake and I get just a very, very slight, almost un-noticeable increase in noise from my S-Flex fan and I cannot tell any significant decrease in airflow.

Regardless of what kinds of filters that are used, there will always be the need to periodically open the case and clean the fan blades and everything else. Dust build up on the fan blades, especially the leading edges, has a huge effect on cfm's.
 
I have a HUGE peice of a hard foam /mesh material that i found once clearing out an old
warehouse one time and i took it because it's the exact same stuff thats in my lian li pc70 :beer:

It's not the best filter in the world but it works and it doesnt restrict flow all that much either.

Heres a shot of some in this pic. notice the black filter? it works perfectly fine for me.
frontfilter640.jpg
 
Immortal_Hero said:
I got 4 of these in the mail last night. I hooked up a Yate Loon to an extra PSU hotwired and moved the filter on and off the fan and well they suck. I will not be installing them as they cut air flow to almost nothing. I will just blow out my case once a month.

That's funny, I find it to not be too restrictive myself. I have 1 of those installed on the window of my Coolermaster Praetorian 730 case over the fan of my heatsink and I can definitely feel a suction off of it. But then my filter isn't directly connected to the fan but rather it's about 10-15 mm above it on the case side itself. I had to do this because of the extreme height of the hsf I'm running, which is a SI 120 with a Delta GFB on a fan controller. Of course the GFB @7v has a lot more suction than a Yate Loon @12v too.

Nagorak, if you are worried about negative pressure in your case with the fan filters then simply install 1 more intake fan in it, like maybe on the case side or something. Or replace a smaller intake fan with a larger size, like replacing an 80 or 92 mm intake with a 120 mm Yate Loon.
 
im getting some really thick mesh for my intake fans. but honestly its only to cool my hard-drives. the rest of my system won't suffer. i'd rather not have tons of dust. but what i did to combat this is i got a router and made a bunch of slits on my case side and put mesh over that, lots of passive intake because i have like. 5 fans out-take, and 1 fan intake.


(hooray for watercooling)
 
Recently I decided to upgrade my computer after a long period and while I was at it, I thought I would revisit my cooling setup. I have always been a little concerned that my case might have negative air pressure, and with some of the newer graphics cards it appears that they exhaust outside of the case, so that only makes things worse.

I would definitely prefer a case with positive pressure and this is initially how I set-up my computer. My concern is my intake fans all have filters which cutdown on airflow. So, even if the rated air intake is higher the actual air intake may be a lower rate, thus negative air pressure.

Does anyone have any idea how much the average wire mesh filter cuts down on air flow? I would guess it must be a significant amount, so I would appreciate any rules of thumb or links to guides on this topic.

My friend knows about the average wire mesh filter cuts down on air flow. I will contact him so that I can post the answer here. :D
 
I read a review on this, but I can't find it. The gist of it was that the mesh with the larger holes'll catch most of what the stuff with the smaller holes will with significantly less airflow restriction.
 
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