case fan filter enlarger

If you use 3m dust filters on your PC case's intake fan and you room is very dusty like mine, you'll know that as a consequence of the efficiency of 3m Filtrete air filter's efficiency, they do clog up quickly. Now one way of increasing the time in between filter changes is to simply increase the surface area of the filter. This also has the advantage of slightly decreasing airflow resistance.

You can do it in 3 ways. The usual way is corrugations which as a bonus, do not increase by much the volume of the entire filter apparatus, i.e. it doesnt become bulkier. Example

The second way is to change the filter from a flat surface to something 3D like a hemisphere, a cuboid or a pyramid. However, I haven't been successful at figuring out a way to do the first 2, I'm forced to do the third method.

The third method keeps the filter flat but simply increases the X and Y dimensions. As a disadvantage, you will increase the volume of the filter apparatus i.e. make it bulkier and you will need an adaptor which in this case is also an enlarger.

The 2 pics below are my filter on a 120mm intake fan after around 3 weeks. Pretty dirty.

 

OK so we need an adaptor/enlarger. I am going to make one from a box, or anything vaguely rectangular. I was thinking about the old mythbusters adage, if its worth doing its worth overdoing.

And that is why I got a rather large box. Its plastic so its light and cheap and not too hard to cut. Since only the X and Y dimensions need to be big, I can skimp on the Z dimension, i.e. its tall and wide but not deep. I present to you, an A4 document case. Hey, the larger filter surface area does mean it will take a longer time to clog up. Bulkiness and looks are of secondary importance to me so I will put up with this.



First on one side I mark the outline of the fan and the 4 holes for the screws.

Next I flip to the other side and drill a hole then move the drill bit sideways to create an opening for the tip of the tin snips to get something to hold on to.



While cutting with my not too sharp tin snips, The material started to crack so I placed masking tape around the perimiter to reinforce it. You may tidy up the cut edges with sandpaper, a file or a sharp knife.



Now flip to the fan side and repeat. The holes for the screws are already drilled and they are under the masking tape.







Now I think I made the hole a bit too small and the dull tin snips were hard to use so I just decided to make a few cuts and bend the edges to enlarge the hole size. Looks untidy but my hands were tired from using the tin snips



I next added self adhesive velcro strips, the hook side. I had to throw away the loop side.



I then re screwed it back on the side plate of the PC case. The Orange plastic thing is a previously existing. 120mm to 90mm fan adaptor. I didnt feel like cutting up my case that day.



Cut the 3m Filtrete filter to size and apply. The hooks of the velcro will catch the filter. Optionally you could tape the edges.



I also taped the seam of the document holder to make it more or less air tight.

And its done!




Link to a smaller version of the above picture.


The end

PC filter upgrade - 3m filters - results

If you read the previous post here, I upgraded my PC's filters to 3m aircon filters.

After around 3 weeks, I noted that the filter is getting pretty dusty. Checking the fan's exhaust, it is getting pretty weak. But checking the aluminum filter behind the 3m filter and checking the fan blades, I noted that they are pretty clean.

So I can conclude that

1. 3m filters really work well, even fine dust is captured. Excellent!
2. my room is very dusty
3. looks like I need to replace my filters every 3 weeks or so
4. since finer dust is captured, the 3m filters last much shorter than cheaper aircon filters


For my next test, I will try using pantyhose. You'll see it in soon in a new blog post.



note: added conclusion #4

the end

PC filter upgrade

If you read my old blog post here, you know that my PC case fans are arranged in a positive pressure orientation and are filtered. Just read the link about the benefits of positive pressure ventilation.


However the current aluminum screen mesh filter on the side and the blue aircon filter on the front do not trap all the dust particles. The amount of dust inside the case is greatly reduced but not eliminated. I can see dust on the fan blades, on the places where the air flows and on the back of my video card. So I decided to upgrade the filters. I used a 3m brand aircon filter.



For a little less than 200 pesos, I get a rectangular piece of filter 18cm in height 39cm long. It is pre folded into 3, this gives you three 18x13cm filters if you elect to cut along the fold lines. For this build, The side intake fan uses up one and the front uses up less than one but the extra was cut off and discarded.

This is more expensive than the old blue one and I hope it catches more dust. I will be monitoring the GPU and CPU temps to see if they rise too much.

For the front filter I continue to use the velcro tape. You can see it as the red and black rectangles on the edges. Since the



Being more transparent, the aesthetics of the case is impaired but for me its an OK compromise.

For the side intake fan I opted to mount the filter on top of the existing mesh filter as a temporary measure. This prevents it being sucked into the fan blades, although the resistance to flow might increase. Some tape and the built in double sided tape is used to help anchor the filter but the main anchor is done by punching holes for the screws.





Ok thats it. Hope this further reduces dust build up. If this works, I'll buy more 3m Filtrete filters as replacements. Its expensive but its less expensive than the parts inside my pc.

Update: I'm saying this again. Yes, filters decrease airflow so you just have to have more fans or more powerful fans to compensate.



the end

Keeping dust out of my PC

My PC has to be dust free since I have a reference design radeon 4850 which needs major dissasembly for cleaning.

I use the same technique used by INTEL and other semiconductor fabs.

The pic on the left is one of the famous intel bunny men. They wear those suits to protect the chips from contamination by stuff flaking from their bodies. Skin cells, bacteria, etc.

The actual factory is a clean room. No, not a room that is "clean". Its called a "clean room". Like some clean rooms, i keep my case at positive pressure so no dust can enter the cracks and seams. Although i try to seal those leaks. The principle is to have more total power in the intake fans than in the exhaust fans. And the intake fans are filtered. The fans keep my case at postive pressure. Look at the pics.

The first pic is the front. Theres a small intake fan behind the filter. You can see the grey brown dust on the filter in a circular pattern showing the location of the fan . The blue aircon fiter is cheap and available in mall hardware stores. Its held on by the red velcro, the hook side. Behind the blue airocn filter you can see the mesh that came with the case. Some dust gets through because the holes are too big.

The next pics are the side. Its a big and powerful 120mm fan with a screw on screen filter made out of fine Galvanized iron wire, the same thing you place on screen doors and screens for windows. Its courrogated a bit to increase surface area. Its washable. I had to use a fan adaptor because at the time I did not want to cut the case, I'm thinking of enlarging the hole and ditching the fan adaptor. BTW, the adaptor and fan and filter were bought in singapore.







Oh yeah, The DVD drives dont fit too snugly so the front of the case has small spaces where dust can enter. I simply folded pieces of paper say 5.25 inches long and 1 cm wide and jammed them in.


update: the blue aircon filter is disposable, but the wire mesh screen is washable. If you are lazy, just use a vacum cleaner. Careful that you dont make the fan spin too fast because it might damage the fan.
And the side intake fan has 2 cellphone cards that serve to deflect the air towards the bottom of the case. Hot air rises so this should help ventilation

update: picture server may be down from time to tome. Aww. Anyway let me summarize
* you can get away with only one exhaust fan, the PSU as the intake fans willdio the job of circulating the air
* cover all openings, including small holes and cracks
* most important - install properly filtered intake fans, and make sure the CFM of the intake fans is way in excess of the CFM of the exhaust fans + any holes or leakage. That way the only way air is getting in is through the filters


update: this website gives more advantages of this setup, plus it has animations



LINK