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Do fan filters degrade air flow?

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Anonymous
a b K Overclocking
April 5, 2003 1:41:12 PM

I've been working w/ PC's for years but I just realized none of my computers have filters on their intake fans. I want to keep dust out but I'm not sure if filters lower the fan's cfm. The filters I'm talking about are the cheap mesh ones for like $1.50 at websites, I'm not interested in homemade. Also, would it be good to put a fitler on a 92mm door fan that blows air into the case?

-Why can't we just challenge Saddam and his cronies to a LAN war?-
April 5, 2003 6:56:45 PM

Yes, filters do decrease air flow. However, so does dust buildup inside your system. A quick check to see if your system needs a filter is to just open it up and look at the CPU Heat sink and fan. If it's dirty and you have intake fans then by all means filter them. If you have cats or other household pets then filter your fans. Otherwise you can probably make do with just a cleaning every few months.

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April 5, 2003 7:04:59 PM

also, unless you're cleaning out your system on a bi-monthly basis, having filters is important because dust can cause shorts in you hardware via static electricity (with airborn dust even worse, as the static can travel through the air)

<b>people are only idiots when they don't realize - when they do it just gets funnier, like a dog chasing its own tail, or like george bush's public address(es)</b>
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April 5, 2003 8:00:48 PM

Anything in the high velocity path of a fan is going to reduce it's airflow. Simple physics... you are decreasing the area from which the fan can draw air.

I know you said you aren't interested in homemade filters but the very best filters you can use are those shredded nylon scrubbing pads you get at the grocery store. They are about 6" square and 1/8" thick... and they impose almost no restriction to airflow.

On the point about Static... Yes you can get static accumulations inside computers, but they are only dangerous to isolated components... eg. a CPU chip held in your hand. In circuit components can and do very effectively bleed off static into the system grounds.


--->It ain't better if it don't work<---
Anonymous
a b K Overclocking
April 5, 2003 9:05:17 PM

Hmm, maybe just a little extra work in making my own filter would be worthwhile. So how would I attach the nylon pads after I cut them to my needed size?

-Why can't we just challenge Saddam and his cronies to a LAN war?-
April 5, 2003 10:37:52 PM

I just tape them over the fan openings from the outside... between the intake fan and the plastic front cover of the case. No cutting, just 4 bits of tape across the corners.



--->It ain't better if it don't work<---
April 6, 2003 5:05:13 AM

you can also (indiscretely) get a pair of panty-hose n use it as filters too, mount 'em the same was as the scrubby pads (he means somethin like an "SOS" or "Scotch Brite" dishwashing srubber pad).

<b>people are only idiots when they don't realize - when they do it just gets funnier, like a dog chasing its own tail, or like george bush's public address(es)</b>
April 6, 2003 5:53:49 AM

Try blowing air through panythose, even single layer, sometime... very restrictive.

(And don't you dare ask how I know that!)

--->It ain't better if it don't work<---
April 6, 2003 7:39:43 AM

indeed.
Fan grills, filters, punched casefan holes... all block the airflow to varying degrees.

with my case the front two casefan holes dont have fans, but ive left the filter intact.
the sidehole, which i believe most of the air comes through doesnt have a filter... but im usually opening up my case every couple of months anyway, so a quick dust does the trick.

whip off the fan on the MCX_462 and clean the heatsink for maximum effect.

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Anonymous
a b K Overclocking
April 6, 2003 4:45:13 PM

Hey, it's a reason to ask my girlfriend to take off her pantyhose.

Teq: Thanks a bunch for that advice, I've done some homemade "tape and rubberbands" style stuff on PC's before, so I'll try your idea.

-Why can't we just challenge Saddam and his cronies to a LAN war?-
April 6, 2003 6:37:17 PM

Just a recommendation on the use of "Scotchbrite" or other scrubbing materials:

If you can find it, get the white stuff rather than the green, grey or maroon (or whatever other color you find). The white has no abrasive in it, the others all do. While its quite well bonded to the fibers, the abrasive can only do harm if it gets into things like fan bearings, etc.

I recommend a hardware store to find the white.

What I use for intake filters is 3M's "Filtrete" material (for window air conditioners) spread over a piece of aluminum expanded metal. I was able to fit this under the plastic front cover of both my Antec cases. I "dome" the expanded metal as much as possible to increase the surface area and stil seal off on the edges. The expanded metal is just a piece of "rain gutter screen", again available at many hardware stores.

With any filter system, the key is to have as much filter surface area as possible. That reduces the flow resistance, and also allows a larger surface area to collect the dust so cleaning/changing filters is reduced (but not eliminated). The problem with filters that go directly over the fan is that they have a small surface area so are restrictive even when clean, and get dirty and thus more restrictive very quickly.

my $.02

BW
April 6, 2003 8:47:39 PM

I'm not talking about scotchbrite which has a backing on it that totally blocks all airflow. Shredded plastic on one side, abrasive cleaning pad on the other... not what you want.

The pads I linked to are the same stuff they make furnace filters from... just shredded plastic fibre (They do come in lots and lots of colours but the ones I have are green, like the picture.)




--->It ain't better if it don't work<---
April 6, 2003 11:30:32 PM

The local hardware store for a furnace filter. The cheap $1.50, flat, blown plastic kind. Not the pleated filters. Pull the cardboard frame off the filter and just cut the material to size. Should be able to get a good dozen out of each filter (18x20).

For it is not what is seen, but what is not seen. :eek: 
April 7, 2003 12:28:34 AM

One word:

Swiffer

Cheap and you can cut new ones instead of cleaning the things. Used tio use one as a filter on an ionizing negative cleaner when I ran a film lab. worked better than the stock mesh (scrubber type)

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April 7, 2003 12:50:45 AM

OK... just went to the store and got some more of those scrubbing pads I was telling you about... they are Tuffy brand, not Scotch.


--->It ain't better if it don't work<---
April 7, 2003 4:59:18 AM

i have no experience with the stuff, but do you think swiffer would reduce airflow too much? it doesn't look like it's made to have air going through it...as opposed to a furnace filter like one person said. i like the idea of not cleaning them though.
it sounds like it might work better than scrubber pads...any thoughts (from anyone)?

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April 7, 2003 11:39:47 AM

IIRC, they are 2 ply, so you only need to use one ply.

<font color=red>*</font color=red><font color=white>*</font color=white><font color=blue>*</font color=blue>
... And I'm proud to be an American, where at least I know I'm free, and I won't forget the men who died, who gave that right to me.
April 7, 2003 12:20:36 PM

I use the grease filter plastic stuff from cooker hoods.
April 7, 2003 2:11:22 PM

Ok...next time you go out for groceries take a look at the pads like the ones I posted a link to... they are woven/shredded plastic, mostly air, and offer little if any resistence to airflow.

I'm not talking about cloth, cleaning pads or steel wool... this stuff is nothing like "swiffer" pads, scotchbrite or a dishrag.

Look at the picture again... you will see it's the same stuff they make funace filters and humidifier mats out of...



--->It ain't better if it don't work<---
Anonymous
a b K Overclocking
April 7, 2003 8:51:30 PM

Maybe you could use a K&N airfilter, or equiv from an automotive application. The only problem would be mounting it and blending it in to look as if it were part of the PC. Those are designed to combine good air flow with good particle filtering. It might cost alot though.

I've been considering this myself as I could care less what my system looks like if it performs well, and this would allow me a little more time between cleanings.
April 8, 2003 4:43:46 AM

Teq,

"Scotchbrite" is 3M's brand for exactly what you pictured in your link. That would be a "Scotchbrite Hand Pad" or a competitors similar product. "Scotchbrite" is the basic "non-woven", usually with abrasive coating that comes in lots of forms, varying in density and coatings. It is often laminated or bonded to other things like sponges, etc.

If what you are using is a "scrub pad" or "scouring pad" it probably has abrasive in it. If you don't believe me, try cleaning a copper bottom pan with it. If the copper gets shiny, it's got abrasive in it. As I said, the abrasive is pretty well bonded, with most of the loose stuff just at the cut edges or anyplace you "abuse" it.

I'm no computer "techie", just a hobbiest. But I do know my "Scotchbrite" since I work for 3M :wink: .

BW

Knewton: I've got some K&N filters, but they're for small (2" dia.) carbs so I don't know how well they would work. I'd have to make some kind of snorkle or something. It might be quiet!
April 8, 2003 5:21:08 AM

I am telling you that is not what I am talking about.

I know what scotchbrite is and this ain't it.

I've got a couple of dozen of the pads here and it's just shredded plastic nothing on it, nothing in it, nothing bonded to it. Just a thin pad of shredded nylon plastic.

If you would actually go into a store and look for the stuff I've described you would find it... at about 25 cents per pad.








--->It ain't better if it don't work<---
Anonymous
a b K Overclocking
April 9, 2003 2:09:53 AM

I just found some seemingly high quality non-homemade filters. They're aluminum and the description says they're high performance.

Sorry, a clickable link to this site wasn't working for some reason...
http://www.nexfan.com/80almefanfi.html

What do you think Teq? I think it's much better than a cheapo one like this:
http://www.nexfan.com/80mmfanfilter.html

-Why can't we just challenge Saddam and his cronies to a LAN war?-
April 9, 2003 4:39:20 PM

They look ok... but until I tested one myself, I wouldn't want to give an opinon.



--->It ain't better if it don't work<---
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