DIY room air filter experiment
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- čas přidán 8. 09. 2024
- While pondering buying a HEPA style air filter for my bedroom, I noticed that there wasn't much info on the availability of replacement air filters for many of the units being sold on eBay.
I started looking at general purpose filters and discovered tests had been done on various household materials to determine their effectiveness as filters for emergency mask use.
Some of the most effective filter materials were paper towels, coffee filters and other similar random-lay wood fibre materials.
Research suggests that standard kitchen paper towel may be capable of filtering around 95% of 1 micron and larger particles. Given that dust tends to range from 1-100 microns and mould/mold spores are roughly 4-20 microns in size it suggests that a simple piece of kitchen towel or multi-ply toilet tissue could theoretically be used as a cheap disposable filter.
Do not use paper as a fan filter on a computer. They require coarse high airflow filters to keep things like fluff and hair out.
I designed a prototype 3D printed housing (can also be made without a 3D printer) using a standard low power illuminated 120mm computer fan to pull air through a layer of paper towel. It relies on a low volume flow of air to hold the filter in place on a platten and filter it slowly and continuously. It does this with almost no noise and an extremely low power consumption.
This is an ongoing test. Let me know what you think of it.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
www.bigclive.co...
This also keeps the channel independent of CZcams's advertising algorithms allowing it to be a bit more dangerous and naughty.
"Always going to be available from your local supermarket..." 🤣
Oh, how quickly we forget.
Haha, yep, just from a year ago of this video!
To be fair in Scotland we had very few problems, I'd imagine there'd be even less on the Isle of Mann. That said I did chuckle at that lol
No, that was caused by idiots bulk buying the paper for no reason, if everyone bought it at normal levels it never would've happened, all toilet paper production is done locally in basically all countries, there was never going to be a shortage.
@@Axodus: Regardless of the reason, or if it's even a good one, the shortage still happened, obviously.
@@HelloKittyFanMan. the cause of the issue was stupidity; because some people don't understand the absolute basics of logistics.
Weigh the paper then leave it running for a week and then weigh it again. Would be interesting to see how much it collects
you'd have to do it in a very controlled atmosphere, or you would be measuring the moisture absorbed by the paper.
@@SwissPGO or you just have another piece that sits next to it as a control
You can just look at it and see the dust.
@@gasdive agree, i remember like a decade ago living in the city over a trafficated road and leaving the clothes out to dry, if you leave them 3-4 days you could see the whites starting to became gray..
@@lesto12321 when I was a kid if you left clothes out to dry they would turn red. The steel works has been demolished now.
I'd set it up with a spool to hold a whole roll of toilet paper, then have a servo to auto feed one sheet a day across the fan
Was thinking the same...
You could collect the sheets and use the clean side as dunny paper, adjusting the servo's speed according to your diet.
Beat me to it. Have the servo drive so slow that it would move approx. one sheet of paper across the surface of the fan per day! 👍💨
@@rogersmith9808 well I was actually thinking of just zipping a full sheet across at a set time of day. Pause the fan for a few seconds first, should be sweet
Best idea
Just imagining Big-HEPA knocking on your door telling you to knock this off right now.
lol
or giving him loads of money to take down the video
Patron philosopher of engineering - Mediocrates: "It's good enough"
In engineering, good enough is perfect.
Maths is always true, but physics is what we interact with even if there is magic, and engineering is leveraging the difference between them for use.
Perfection is the enemy of the good.
I can't wait to use the Mediocrates riff.
Also if you want to buy fans for any filter application get "high static pressure" fans, which are quite popular with the PC watercooling community, and thus available at a reasonable price
🤔🤷♂️
They're optimized to deal with the restricted airflow of radiators that can be 40mm thick, or even more depending on the type. The lattice pattern inside them is quite restrictive, but that's how the heat gets transferred out.
Agree, Arctic P12 is a reasonably good one and quite cheap.
A problem is that HSP fans are rather noisy and power hungry.
I was thinking that I saw that Corsair had fans optimized for high static pressure and fans optimize for volume.
There's this channel called GamersNexus dedicated to thoroughly test all sorts of computer hardware including fans and cases. One of the things they have demonstrated in several videos is how filters (or any similar materials) positioned right next to the fan decreases airflow drastically, so it's a good idea to have some space between the fan and the filter.
@Tamamo We're everywhere...
@Tamamo Oh but here are some!
@Tamamo Bless Tech Jesus
All hail Tech Jesus
Followers of tech jesus is everywhere :3
The "buffer zone" as you call it, is called a "Plenum." :-) Nice design!!!
Ah yes, like engine intake manifolds.
@@f.f.s.d.o.a.7294 nice to know, thanks!
I think having a similar plenum on the bottom with Vents in the sides to direct the airflow not down but out 360°
Funny how the same word is used for the giant void above lowered ceilings, with Americans referring to cables rated for fire in such voids as "plenum cables".
@@johndododoe1411 it's because it's actually a place fans exhaust to in data centers. A void in the ceiling that carries hot air towards exhaust and also fits cables. Those cables need to sustain continuous boiling heat and obviously need to be fire retardant, also because you can't have burnable stuff above head level where it could fall on you in a fire.
I have one of those HEPA units,. and an important piece of the puzzle for filters is that there is a very coarse (open) filter that catches large dust bunnies. It's almost just a fine mesh, but it can be cleaned out with compressed air. It does most of the work, and it makes the HEPA last way longer. If you just put that mesh for the fan in front of the filter, it would catch most things. But given that the main filter is just kitchen roll, there's no need for 2-stage filtering, really.
Same with mine. The material looks like a foam sponge....
"Carbon pre-filter" is the magic keyword... but, as you point out, this will complicate our design, as we wouldn't want one of those scratchy pre-filters directly touching the paper towel, lest the pre-filter take bits of the paper towel with it, ruining the benefits of both. Real HEPA filters are somehow not prone to releasing fibers in this way, which is probably one of their benefits (maybe putting our paper-towels in a "sack" of some kind could fix this, but now we have to clean or replace the stupid sack....)
It's kitchen roll. a large particle pre-filter is unnecessary to prolong the life of the micron filter. The carbon pre-filter is an odour control and not part of the design. I too use a HEPA filter that is a noisy fan ("SilentNight"). It takes about an hour to filter a singlebed bedroom. Nobody seems to be mentioning that the volume of airflow is pretty important to the effectiveness of "cleaning a room". Bedrooms are not sealed boxes and dust settles. Even if this didn't work as well as a noisy high volume HEPA fan, placing it near an open window to pull down the pollen and road pollutants seems like a great idea. Or even blocked into the open window itself. Catch it before it falls on the bed linen. Low power, constant use. Great idea.
Well, having a metal mesh would mean less waste, which, if this idea does spread, means way less waste over time.
I use the same principal with my camping water filter. I use a coffee filter before the main filter to get some of the larger particles out and it makes the filter last way longer.
The only problem you are going to find is that Toilet tissue actually sheds particles of itself, so as your device draws in air and filters out dust and dead skin out of the air, it is replacing that with paper particles instead.
I wonder how many wood particles you can breathe a day before it becomes a problem.
edit: actually the problem would probably be the chemicals used to treat the paper, specially for expensive toilet paper...
@@iwannabeanarwhal That's the reason we a 1/2 ply household. No chemicals on these booties
@@iwannabeanarwhal so does this mean if we use toilet paper that is unbleached (and eco friendly, which is sold a lot at niche shops) this could be a viable alternative?
I do have a pm 2.5 sensor I'll test this out myself wrt cadr etc
@@MayankJairaj any updates
I was just looking up ways to tone down the amount of dust in my bedroom and now you’ve made this video. Your timing is impeccable.
Around 90% of dust in a home is dead skin cells from the humans and pets in the home...
@@Mark1024MAK this has been debunked a number of times.
@@HMPirates
80-90% of the dust in your bedroom is dead skin , the rest of the house would have more dust from outside due to airflow and people dragging in dust as they enter the house .
@Martin Shepherd yeah, that's seems about right.
@@Mark1024MAK if 90% of your dust is dead skin, u need to shower more often
A couple of comments. I like the idea of the void, and making it round. If you were using a smaller fan, or didn't mind an increase in overall size, you could make the top plate larger than the fan diameter and engineer a venturi effect with a shaped chamber. When testing, you could use one of your smoke machines which would generate obvious particles for showing the effectiveness of different paper types, also it should indicate how much air is directly recirculated because of the top/bottom pressure difference and how long it would take to cycle through the air in the whole room.
Awesome tips.
Basically Major Hardware style effectively. tho he tests fan blade designs mostly. But definitely a good idea.
According to youtube, you posted this comment a week ago :S
@@CantCampThereMate Thats because Patreon-supporters get early access I assume.
I don't believe the Venturi effect has any application with this kind of contraption the way you may think.
Red lights calming, that's what I'll tell my passengers in a traffic jam 😁
Unless you’ve just blatantly driven through some red traffic lights...!!!
Tell that to the military, who use red light in rooms where soldiers and sailors ready themselves for storming out into night combat (official explanation is that the eyes in that light will accomodate to the outside darkness, but one has to wonder what they quietly found out about aggression, as the lighting has apparently been extended to groups that won't exit into the night.
Train conductor here, me too! My passengers are going to love me... or lynch me. LOL
I spent some time in a darkroom when learning photography in the mid '90s, and the dim red light felt quite strange to work in. When stepping out of the darkroom, everything felt super bright and cyan tinted for 15 minutes. It was weird.
@@ZacabebOTG hahhahaha I know! I did some work like that as a trainee. It was the weirdest feeling.
I made mine using an existing 7inch fan and a circular HEPA carbon activator filter taped in front, and it works brilliantly. I bought two filters on offer for £14.99 so have a spare. The air in my little office is much cleaner and I breathe easier. I have asthma, so this DIY came out very well. I used 2in wide tape to get a good air seal, switched on my fan and bingo! It works very well.
There is a video showing a 12inch box fan, and all you'll need is a furnace HEP filter and a roll of 2in tape, and it's made in 5 minutes, and that works very well because my friend made one. So it's worth doing, and satisfying for saving £££ by making it ourself.
I love all your videos, Clive. Don't change being the great bloke you are. I've learnt so much from your vids. You cheer me up, too!
I use a disposable mask for the filter material in a small filter I have. It is not a hepa filter but it works incredibly well and has good flow.
Random thoughts on your project:
First of all I really like what you are doing!
The void will serve to even the air flow across the entire area. From tests I have run on bus radiators I can tell you that the velocity across the diameter of a fan varies a lot, even reversing direction near the center.
Personally I like the square grid in your current design. It supports the filter well and produces little blockage of the filter area.
If you have access to a sensitive balance you can measure the efficiency of various design elements by weighing the filter before and after use to see how much mass is collected. Probably should place samples in a box warmed by a lamp to assure dryness before weighing, and run a "control" filter unit to account for variation in cleanliness of the air.
I'm looking fotward to hearing your results!
I did this a few years ago with a bathroom fan and a round HEPA filter used for vacuum cleaner (those bucket kind of vacuum cleaners had perfect size filter for the fan). No 3D printing needed, just zip-tied them together. It's ugly but really works. Filters are cheap and available anywhere
👍
Yeah, something like Levoit 300 HEPA filter, xiaomi, etc. they will perfectly fit a 120mm fan on top. There are even some Ali sellers selling the filter + fan + PSU combo with an adapter plate.
@@jaro6985 ,
[Noted] 👍
You could make a device that uses a roll of toilet paper and slowly pulls it across the fan opening, like a casette tape. It could run permanently for a year without touching it.
I like it! :-)
LLAP
That’s a Great idea.
That would mean you have a reservoir filled with mold growing on it?
You should add a way of automatically getting rid of the used toilet paper, e.g. flushing it down a drain or so...
that's a very good idea..
@@Keneo1 have it roll onto another roll enclosed top and bottom so they are not exposed to the outside air except when its rolling across the fan..
I wonder if having a tapered area for the filter would help? Like have a larger filter than the fan, and have ducting that adapts it. Or have a corrugated mount that lets you put more surface area of kitchen roll on the front, which would help increase airflow.
Those are 3d prints that are available online actually. And they are super easy to model. Even something like a 200mm fan to 120mm fan adaptor could work wonders.
A venturi would help to suck air in efficiently, up to some extent.
I came here to say this and you beat me to it.
A cylindrical filter holder would do the trick, without having to deal with sealing the edges of a corrugated holder. The vacuum created by the fan should still be enough to hold the paper in place.
just go to the store and buy a real filter then cut it this is what i do for my A/C vents to double up the filtering (i use clear tape to attach it )
it's pre corrugated the second filter gets dirty as well
I have a pc running in my garage 24/7. To dust proof it, I built it in a car tyre with a car air intake filter as sole air inlet. I run 3 fans as exit. 2 are mounted on the 120mm aio watercooler. Every few months, I blow that filter clean with an air compressor, and when I do maintenance on my car I replace it with the car's old filter. So far it's worked great!
I had no idea that paper towels were that good though. I might utilise that knowledge when I upgrade my home office's air circulation.
I use Swiffer dust pads on / over my filters to pre-filter the dust so the real filters last longer. It's amazing how much dust they capture.
Same! Also with cut pantyhose to minimize Swiffer fibers from getting into the computer.
@@MMuraseofSandvich ,
Interesting application 👍
What about microscopic life on the surface of filters though, I may be wrong but aren't these filters perfect feeding and breeding grounds for them as you're pulling their food from air in one convenient spot.
In that regard regularly putting filters inside hot chamber with hydrogen peroxide seems like a good idea to me.
@@Kinnikinnick It depends on the humidity in the room and if you room is humid enough for the media to get wet enough that moulds and mildews can grow on it with a constant draft across it then you probably have much bigger problems. :-)
Moulds and mildews grows well on humid areas because there's no airflow across it helping the surface to dry out, that's why you mostly only see it in poor ventilated areas of a room like in corners and behind furniture and so on. Ventilate the room better and it will go away.
@@Dingbat217 With this device, airflow won't be across the surface, but into it. Mold spores and microbes will be intentionally gathered and retained by the airflow, making it a matter of nourishment supply in the form of moisture, dust and discarded skincells.
I save used dryer sheets from when I do laundry, then I affix them to the back of my computer air intakes as filters. It collects dust pretty well and makes my room smell nice too. I change them once a week, and I can see the dusts collected and do noticed my bedroom has less dust as a result.
Also a cleaner pc, win win!
@@umxrr8677 Ya, I forgot I initially did it to keep the inside of my desktop from getting too much dusts. lol
Holy shit sir you are a genius.
I thought I was the only one that did this...
Did you notice the components running hotter as a result? Unless the enclosure is greatly over-ventilated to start with, I'd expect some loss of cooling.
Another way to measure efficiency of the filtering could be use one of those PM2.5 sensors that you can buy on eBay, to count particles in the room before and after certain amount of time with the fan running.
Checking those out. Thanks for the recommendation.👍
Good Idea!
They're accurate but for whatever reason the 2 I got from 2 different vendors had the same internal fan failure. They have a tiny 1cm square fan inside that is absurdly expensive to replace and a pain in the ass to repair
"...And they're always gonna be available from your local supermarket."
Q2, 2020: "Hold my beer!"
Having the void makes a lot of sense. Another thought: More cross sectional area is definitely better because of the decreased pressure drop needed to flow air through it. This is why most commercial filters have the wavy-shape instead of being flat. Similar to how a large pipe won't have as much pressure drop as a small one (assuming flow rate is constant). Or alternatively, a large pipe will allow more flow rate than a smaller one if the pressure drop is the same. You might even consider extending the height upwards into a square and putting 4 openings on the side with their own sheet of toilet paper. So you would have 5 openings instead of one: one on the top and 4 on the sides. But it would make it bigger in size and it might cause more recirculation.
Now we know who's been hoarding all the toilet paper 🤣. Wish I'd seen this last week just spent out on a mid range hepa filter, oh well when the filter needs replacing I know what to do.
I wondered if this would start another toilet paper shortage!
I like this. Place it on the floor in one corner of the room. Have it blow through some ducting and direct it to an adjacent corner of the room, near the ceiling. Have a tiny ozone generator on a periodic timer near the exhaust vent. Then have an ioniser near the ceiling, over the fan. The room is now like an efficient aquarium filter!
Or, have the fan blowing *up* instead of down, so the suction of the fan holds the paper on. You'd know it was time to change the paper when it fell off because it was too clogged to allow airflow through it...
@@markfergerson2145 when clogged it should hold it much firmer.
Just imagine the extremes.
Put plastic bag with 0 airflow and it will stick extreme.
Not sure I'd put it on the floor, though. Wouldn't it pick up a lot more dirt there than, say, at head height?
Turning rooms into human aquariums, sounds fishy to me!
@@rolfs2165 Well, its purpose is to pick as much dirt it can.... I would be concerned when it start to blow dirt from floor into thr air, if floor is kind of dirty
11:11 "(toilet paper) is always gonna be available in your local super market"
yeah, bout that...
loved the video! I've built my own battery-powered charcoal-filter for soldering and it's the best one i've ever used! Quiet, portable, elegant, compact. If you're into soldering, i highly recommend you build one yourself. It's a fun weekend project and is good for your health. Also, once you've soldered with a fume extractor, you never wanna go back :D
But i like the smell of solder in the morning.
Ditto!
(I'm pretty sure somebody declared that snorting rosin like this caused cancer but then even HP sauce causes cancer... if you dip the rat in it for weeks...)
@@stargazer7644 same here :D
but since i've gone mostly lead-free i gotta say it doesn't smell nearly as good. I've got some natural flux my parents found in a tree tho, which smells really nice ^^
(fume extractors still rule.)
Interesting video, BC! Several comments to make:
1. You absolutely do want that space between the fan and the filter media. This space is called a 'plenum' in the HVAC/aerodynamics world.
For one thing, a plenum keeps the filter media away from the individual 'pulses' of air pressure that are created by each fan blade as it passes a(ny) given point on the intake-side just above the blade path (and thus, avoiding a 'fluttering' effect).
But mainly it increases efficiency, as when the filter media is held just above the fan blades (as your multi-hole plenum-less design would do) the fan motor hub blocks any airflow through the filter media area directly in front of the fan hub. Depending on the hub size relative to the overall fan diameter, this can be 10% or more of the filter surface area. Using a plenum lets the entire filter media surface area flow air, so it is less restrictive, filters more air per minute, and better uses the whole filter media.
2. consider using a very coarse wire mesh instead of the grid of PLA in your design, to support the filter media. The diameter, spacing, and total count of the grid supporting the media will have a major effect on the total airflow, a small effect on the noise, and will affect the filter media use (big fat grid lattice blocks any airflow through the grid supports themselves; the wire in a wire mesh is usually round in cross-section, so less restrictive than a flat plastic cross-section). It is (always?) a tradeoff in adequate filter media support vs airflow restriction/media blocking.
3. The tiny little clear rubber/silicone 'buttons' you have used for the feet on your prototype are a bit too small, and probably too stiff, to best isolate any fan vibrations. I'd use a softer silicone/rubber foot, that is thicker (taller) and softer for that.
FWIW, I've been using a good ol' 20" 3-speed box fan cheapie for room air filtering. I made a simple frame of 1/2" square-section wood, with a chicken wire mesh stapled to it to support the paper towel (2-ply, only the best! lol) filter media, for room-scale air filtering. I just use a couple pieces of gorilla tape to hold the frame on the intake of the box fan. WAY cheaper than using OTC HEPA filters. I keep one running 24/7 on low speed, to tame the kitty-litter dust menace in my cats litter box area, and it works great.
Pro Tip: When you go to change out the filter, first unplug the fan, and then use a spray bottle with water to lightly spray the filter media BEFORE you disturb the filter. That way, the dust/pollen/yuck stays stuck to the filter paper and doesn't just get back into the air from handling. Really helps.
Tip#2: If you need to filter out a room really quickly, take the filter into another room and spray just a little Endust (or similar dusting agent) onto the filter before returning the filter to the desired room and running the fan. It makes the filter extra sticky to dust and really loads it up quicker...make sure whatever dusting agent you use, is pleasing and not full of irritating chemicals if you are sensitive to those.
Love your channel, always interesting. You Scotch-re-distiller-you! :-)
I have an air purifier from a company called Idylis. It's one of those whole room purifiers and in the instruction book for it literally says to just buy carbon and HEPA filters in large sheets and just cut it to fit inside the machine
Some of the HVAC specialists on this channel would probably be best able to advise on the location and size of a plenum.
👍
Even if it fails as an airfilter, it's at least a perfect way to dry your toilet tissue!
Are you saying that you reuse yours!
@@Mark1024MAK yeah, by the third use you just gotta dry it out.
I just flip it over for the second use. But keep a corner clean. So you clean under your finger nail.
Nice one...you almost had me spitting out my coffee! 😂☕
I hear that the market for pre-loved toilet paper is as yet unbelievably untapped, as is the market for teflon toilet tissue.... go for it lads
Yo BC, You gotta do an EP (Electrostatic Precipitator) Filter video. High voltage...you know you want to. :D
You should make a plate that has magents where it meets the screws on the filter case so you can put the paper between them and turn off your computer without the paper falling.
This is an amazing idea, please do an update video after testing it. To see how much it can filter, how often you replace the filters
I remember eons ago an ashtray that had a fan and filter built in. It worked best if you didn't actually use the ashtray. And didn't smoke.
My Da had one and all it did was to spread filthy smells throughout the room toward anyone near. Didn't come with a charcoal filter.
Hi Clive, I worked for a computer company in the 1980's and this company felt that that office minicomputers were more useful than mainframe computers in computer rooms. Of course one of the issues was fan noise. An article was written in an internal company newsletter that pointed out that a big fan at a lower speed was much more quiet than a small fan running a a higher speed but moved a similar amount of air. Many experiments were done with geometry of the fan blades but in general the biggest issue for noise was the velocity of the fan blades measured at the tips of the blades. I propose that the you build a bigger holder that can accommodate paper towels and a slow large fan. On the bottom of the holder build in a horn (similar to a speaker horn) to direct the exiting air away from the top of the unit and also to direct it into the room so that unfiltered air in the room is mixed with filtered air and then returned to the input of the fan. You can try different paper towels for a known period of time and weigh them to determine how well the filter is cleaning the air. If someone else had similar comments, please excuse the duplication.
I also suggest Wikipedia Ducted Fan and Ducted Propeller articles.
I would recommend to enlarge the air void further. The so called air void (duct) smooths the turbulence produced by the suction above the fan blades. And it elevates the suction power if it is made longer. I would experiment with a double that long air void. Even I propose to place a taper shaped air distribution / guide below the fan that smooths the out flow of the air to the sides. A apron like air guide at the edge of the outlet pointing some degrees downward can reduce the feed back to the intake. All these thoughts are to smooths the air flow out of the fan. Less turbulence more efficiency. That's my two cents.
The paper towel as a filter idea is genius. I've seen little 8" and 12 inch filters for hvac use, and they're about $6-$10 each, good for 90 days, thought of making a similar thing with those...but this seems to be cheaper and much more convenient. Maybe come up with a way to mount the fan horizontally, stick a few ionizer electrodes before the filter, louvres on the output side, and one of your nifty 3-d printed lamps on top. Actually, all sorts of potential. You are a real gentleman for sharing this little stroke of genius.
I built something similar and use it for years now.
Originally intended for soldering, I ended up never turning off some of them.
In case I open my window on new years, those filters clean the room in less than a minute when I have them on full blast.
One version uses a fin grid array on the output and that helps to direct the air in the direction it blows into.
A unaided fan will blow most to the sides, as that is where the centrifugal force throws the air.
Your idea to space the fan and the filter is pretty good.
When the filter sits close, most of the air will just go in through the centre of the filter and the sides will stay clean.
With a spacer like yours, the filter is used more evenly and will last longer.
Maybe you can build a tower like spacer that allows for filters on the side, so the bigger filter area makes it easier for the fan to pull air through.
You should buy the "extra soft" loosely rolled toilet paper so you can have the privilege of paying twice the price for half as much.
I got caught out by a certain 'quality' toilet paper maker's products appearing in one of the cheap supermarkets. The inner cardboard roll was much bigger than their normal products, therefore less sheets, hence the cheaper price...
Real men use sandpaper.
@@jmonsted wire wool!
@@dangerotterisrea Toilet brush!
@@Lagggerengineering Cacti.
I like this...I've been doing something similar with a 20" box fan in my shop for years. The fan sits on some wood legs and basically blows on the floor just like yours, and there is a 20x20 furnace filter on top. Not micron level, but it definitely helps in a room full of dust.
I have a box fan, and I just stand it up in an empty space, and the pressure from the fan holds a fiberglass filter against the fan itself.
@@tbelding Yep, especially if you get a finer grade of filter. I use tape but it isn't totally needed. I would be curious on the science behind the air void on top, I have no idea if that would change anything. Mine does not have that.
@@ryanroberts1104 They're called plenums, and they do assist. I'm not absolutely certain, but I believe they help even out the overall air flow - that's why cars have both exhaust and intake manifolds that are shared across all of cylinders, rather than venting them separately. I'm sure that you can find a 'why does it' on an HVAC site.
@@tbelding Right, but what, if anything, does that do for something like this? How does "evening airflow" help in this situation? It's not an engine with multiple cylinders, or a house with multiple vents.
@@ryanroberts1104 From personal experience with these fans (I'm an IT tech), they tend to have a tumble zone around the blades, so they're really only pulling in narrow 'slots'. Remember that there's the frame of the fan on the _other side_, and the hub of the fan is huge in comparison to the blade length. Having the chamber means that the suction on the bum wipe is much more even.
I would think the air void would help if only because it'd do a better job of distributing the air pressure across the whole filter. It probably doesn't need to be very deep though.
Red light in the bedroom is a good idea because when you shut it off, your eyes adjust to the darkness quicker than other colors.
Hi, this is my professional/academic background. Your intuition is spot on - a "buffer" will produce a more laminar flow with a more consistent pressure differential, drawing more air through the filter more efficiently.
To be honest, though, that airflow isn't nearly enough for a room, unless the room is absolutely tiny and you never open a door. Dust is created and circulated constantly - A 90%+ efficiency is great and all, but a tenth the efficiency at 10 times the airflow has the same effect on the air quality of the room.
Also, you may find paper towel better than TP, which may produce a lot of paper dust/lint due to its softness.
For the next iteration, I'd consider automatic replacement of the filter. Imagine ancient scrolls. But motorized. So you'd install a new roll of toilet paper once a month.
Great idea, and if it wound is self back onto a roll you could use it for the intended purposes too. 😱 🤣👍
Challenge is not redistributing the dirt from the old filter back into the room.
We use an air monitor at work that functions exactly as you've described. It takes a representative sample continuously for 31 days.
@rasmis That is genius! Maybe a synchronous motor but geared externally so low that a single sheet passes by per day.
@@dosgos maybe a container with a slot that holds the used "filters"? Like a paper shredder without the shredder. Or with the shredder, but I think that would just launch the particles in the air (though it may help cut down on the volume the paper takes up?).
For the motorized setup, I think a stepper motor would work better than a geared synchronous motor. Would be more expensive than a single motor and a power supply, and it would have to be controlled externally (arduino micro?), but I think the fact you wouldn't have to find or print some sort of gearbox would make up for that.
Also, if you wanted to use paper towels for their presumed better filtering ability than toilet paper, you could probably just saw them down to around the same width. Then it would last even longer, you'd get 2 or 3 rolls for the price of 1.
Finally, I wonder if an ionizer attached to this would help. It would at least help collect the bigger dust particles, but I'm not sure of the efficacy on microbes.
The thing with HEPA filters is that they positively bind the particles inside so when you are changing it you are not releasing the particles back into the room 😁
Remove the toilet paper with a vacuum cleaner, any dust coming off will be sucked with it.
@@teslatrooper but how good is your vacuum cleaners filter? Are water ones as good as paper or what?
You’re a sucker for marketing wank. How does a hepa filter magically do that?
You work for big HEPA I see.
@@lightweight1974 Nah, I just work in industrial maintenance :D
There is some good DIY air filter advice at a site called air-purifier-power. DIY ideas on foam prefilters, reusable activated carbon, bulk filter medium...
I decided to look for an alternative to those expensive room hepa filter devices several years ago. Ultimately I ended up just getting a few $20 box fans and taping 20inX20in hvac hepa filters to the back. Obviously these aren't very quiet even on low but they move VASTLY more air through the filter medium than even the beefiest "room" filter and for considerably less cost.
Interesting. My girlfriend is allergic to pollen and recently we invested in an air purifier. It's really just a big fan with 4 different filters for dust, pollen and other particles as well as some kind of sensor for air pollution levels. The filters are very expensive, so hearing that paper towel is an effective air filter is very interesting indeed.
You should build an automated roller so that you can stick an entire roll of toilet paper on it and have it cycle one sheet per day/week/month. That way you don't have to deal with it until the roll is empty.
At work we have huge HEPA filters that do exactly that. It's controlled by a pressure switch, and will advance the paper when it's clogged sufficiently.
For the toilet roll, a small motor geared down to very slowly advance the paper should work.
Better yet: make a roll on the other side that rolls up.
When after 50 days or so the roll is full (and the other empty), carry it to the toilet to use it for its main perpose.
Actually, when adding a slowly turning system like a clock-motor to roll it up, you have a fresh filter-replacement all day long.
Then you would have a used roll that would still have other uses, not that I can think of one - but the second hand toilet roll market is one of those untapped markets just awaiting for a suitable product.
Edit add - could glue them to back of some cardboard and sell as nano-particle fine sanding paper - tada :)
@@elvinhaak that would just make the bathroom very dusty
Paul Gray could be very useful for compost for the garden or lawn
I would've liked to see the paper after being in use for a few days.
Used TP tends to be yellow or brown, not sure how it looks after a week of constant use but it would prolly smell awful.
me too
Depends on what type of use! 💩
ive done this i recommend A very strong fan 12v 0.45a-5a and waiting around a month with it on full blast 24/7 you will see a slight decolorization so it does somewhat work
Nice idea! It's small enough to sit on a night stand, creates a little light, a little white noise and filters too. The toilet paper or paper towel concept works from ease of use and maintenance. At work we buy filter media in rolls but that's not something your average household would be able to buy easily.
I have a standard Blue Air Pure 411, and although its fan frustrates me a little with its on, loud, and very loud settings (we have it on the lowest as a small amount of background office noise), compared to the DIY efforts, its cylindrical pleated filter design means that it's probably got 100x the surface area of your bit of toilet paper. It's only rated for a small room too - unless you live in an extremely well sealed house, your standard room air movements are going to be significantly greater than what your little filter could deal with.
If I was to DIY another (and I've been considering it), I'd be making my own cylinder and fan unit on the top, and buying the same replacement filters to put around it.
Also, a pre-filter is basically essential to prolong the life of the main filter - ours gets visibly dusty and has a brush down every month or so, and you can simply throw it through the wash every so often too if necessary.
Air void yes, but for the holes, I would imagine that the more open that it is the better. So, the filter support needs to block as minimal amount of air as possible, while still supporting the filter.
Yes. There are many readymade fan grills that could be used for this.
This is correct. Gamers Nexus has done a lot of testing and experimentation on various computer hardware, including demonstrating that drilling more or larger holes in the fan grill of a poorly performing computer case can drastically improve the airflow and thus its cooling potential.
Add a bog roll holder, and a small motor to gradually draw draw the paper across and roll it up on the other side. Maybe use the some clock mechanism, e.g. Flipclock.
This is why I scrolled down before commenting. Exactly what I was thinking. Maintenance free for ages.
Oh Your right i didn scroll sorry
Someone watched Technology connections yesterday 😂
@@LordmonkeyTRM guilty as charged
@@coolfrost6 😃
Use two plates forcing convolutions into the filter paper to increase surface area!
I built one years ago with a fan either side of a spherical "expansion chamber" that had some foam in it. the amount of dust that thing pulled out was unreal. using a black orchid hydroponics fan that's inserted into and old car airbox/filter now and that works really well. Even better if you can exhaust to the outside and use a lighter filter medium.
You need a much larger filter to reduce the resistance. That is usually done by pleating the filter media. A higher powered fan is also needed unless the room is very small and is sealed off from the rest of the house.
If you were to fold pleats into the sheet it would increase air flow and filter efficiency by turning it into a depth filter.
That makes it harder to seal the edges against air bypassing.
Instead of folding pleats, you could make 2-4 TP sheet sized spots for the filters.shapes that come to mind are either triangular or M shaped.
I agree, it would just need 2 3D prints to clamp the paper between 2 sets of alternating vertical slats and a surround. The frames would have a zig-zag embedded which clamps the edges of the paper, sealing it. A bit of a faff to design, but it would improve efficiency.
@@BigClive you could make it somewhat like a small cabin. Double your filter area and make a nice aesthetic. Just have the cabin roof as your air intake.
🤔😑😶👍
What you designed is perfect for a bench solder sucker.. pulls away from face and the circulation would be perfect. Try that and see what flux etc is gathered. I concur with Mark Garth.. use your HVAC friends and have a plenum review. (Just had a flash of five bearded wonders with overhead spot light on tiny fan all smoking cigars and pondering). Also you can by bulk HEPA and MERV filtration media, but can also take apart a low MERV comercial filter.. sometimes cheaper.. like a 3M filtrete and 'take it to bits' . I like the idea of just having it suck the media - at least for bench and like an electronics room filters. easy to change when you think of it.. have a slot on side for media. haha could also print one for bathroom and have TP roll pull over fan :/ ? dual use - first filter then err no waste anyways)
While the multiple circular holes are aesthetic I think the first version with the cross bars would be better. The air flow of the "holy" one would be restricted as less open surface area.
Hexagons would also be a decent choice
You won't see the holes when the filter is in place anyway, so just matching the wall of the fan as closely as possible for support and a seal would be best.
Excellent idea. Thank you for the inspiration. I like the dirt-cheap filter-medium concept of using tissue rolls. Couple of suggestions:
Add a good length of clothes dryer exhaust hose to the exhaust side of this filter. That will prevent ineffectiveness problem of exhaust air looping back into the input. Use an exhaust plenum with hose attachment cylinder on the side and the fan mount on the top.
The air intake / filter-medium-holder could consist of a cube shape. You'll have 5 sides for filter-medium and the bottom side for the fan. Drawback is that you will be needing something to hold the sheets in place, because your fan will only start to hold them in place when all 5 are in place. This shape would eliminate the need for an intake plenum.
I'll start with a test rig, which will later be converted to a portable solder fume filter on Li-ion.
If you're interested in experimenting with different kinds of fans and their static pressures and you don't have any pressure measuring equipment, may I suggest a good length of transparent aquarium bubbler tube. Fix the end of it in a vertically oriented U-shape. Put some water in that U-shape. Liquid levels in the legs of the U are equal, unless you apply slight pressure or vacuum to the other end of that tube. Set a ruler next to it, so you can put a number on the fan's performance. You can print your plenums with test ports where you can attach this pressure test tube, or just drill a hole in an existing plenum. Don't forget to plug the holes when not measuring.
Back in the early days of home PC water cooling a company sold an acrylic air void for the radiator (car heater core) that actually made a big improvement in cooling because we didn’t have fans designed to deal with the airflow restrictions of a radiator. I think this is a really good idea and would love to see a single or even dual 12cm fan housing, as there are many 12cm fans available that handle static pressure much better without making a ton of noise
Unfortunately, there's a reason that any air purifier (that has any non-negligible effect on the amount of particulates in the air) is large and (at least slightly) noisy. Unless you live in a sealed bunker with precisely zero drafts, I strongly suggest you run some numbers on the air flow rate that you'll need in order to compete against the rate of introduction of new particles from the outside (not to mention the generation of new particles inside), as well as the pressure drop across the filter *at that flow rate*. Also, given the high pressure drop typical of decent filters, I believe it's fairly important to use a fan specifically designed to provide a high static pressure, or else you'll end up on a really bad place on a normal fan's flow rate/pressure drop curve (which, specifically, would leave you with a very low actual flow rate for a given amount of noise/power). Basically, unless toilet paper is somehow a magical filter that is orders of magnitude better than other specifically engineered filters that have come before, this absolutely doesn't pass the sniff test -- please beware of tempting people with health problems away from the actual air purifiers they need to save a few $$$ to end up with something that absolutely doesn't help with their allergies or asthma. I saw this happening first hand during the Sydney Bushfires with similar homebrew "air purifiers"; very sad to see not-so-well off people wasting their money on actual junk.
This is just an experimental passive filter. It's designed for small rooms like bedrooms and is extra quiet for 24/7 operation. Although the airflow is low, it is continuous, and the filter can be changed as often as desired.
@TheHue's SciTech
I was thinking the very same thing!
Consider these other thought:
- in the time you reach a a decent air quality (if even possible) you have breath a lot of unwanted particles already (as it happen anyway in the rest of the life)
- these devices cannot compete with particles that are on a surface that can be thrown in the air simply by walking inside the room...
The filter eventually will clog up but this not mean anything about the quality of the remaining air inside the room...
Anyway interesting and clever 3d printing as always! You are great Clive!!! Keep it up!
Absolutely good points. Maybe to add to this: a small distance between intake and outtake might create a lot of direct recirculation - maybe distance or building it into an object might alleviate that. Paper towels might clog quickly, reducing the air flow. The latter might be partially remedied by a larger filter surface and multiple phases (like a coarse filter on top).
I would be hesitant to trust a DIY system until its been tested though.
It's more a dust collector than an air purifier.
@@BigClive please find a way to measure the air flow. Unless we know that, probably the only way to properly asses if it's doing anything at all is to use a turbidity sensor. Noticing dirt buildup on the filter tells us absolutely nothing about if the air in the room is significantly improved.
It's also possible to make cylinder with mesh on the side and closed top, then roll toilet paper on the side, this will make much bigger surface for a filter
I was thinking about doing a air filter for my bedroom using a cross flow fan but your idea plus bigclive's sound good too and I have the parts to make it
Hi Clive,
Very smart idea IMHO
I think it makes sense to have a cavity as you designed. I think the cavity will negate or absorb any turbulence at the surface of the spinning fan .
Ok Clive, you finally tickled my synapses to the point I just had to jump up and respond. In a past life I was a flowbench pilot, and have had my digits in many a port and orifii (word?) trying to get the best out of whatever was thrown at me. Just remember....you asked ;)
I would use the bigger fan, but only after chasing around the edges of the fan blades with a sharp x-acto blade to trim off any and all molding flash and imperfections. Radius any blunt or sharp edges. Even do the same to the inside of the housing, anywhere air will travel past a corner or edge. Also your idea for a plenum (air void, in Clivanese) is a good one, as the blades would create pulses passing so close to the twalet paper, resulting in possible additional noise (turbulence). Less turbulence = less noise. A plenum is basically a reservoir, of air in this case, and air does 'stretch', so any pulses or noise may be lessened being further away from the aforementioned square of butt tape above it. Also, a round housing to match the diameter of the fan blades would help with aerodynamics, as the air wouldn't have anything to 'crash' into...yep, turbulence and noise again. Also would possibly increase the flow volume slightly, not having to fight with the air that just crashed into the square corners on a round inlet. Having a tapered, or funnel-shape, to the round plenum would smooth things out even more, with the entrance being larger than the bottom. Possibly with a round fan grate found on many computer cases. Round wire will flow a bit more smoothly than a squared-off grid as you have currently. Also it would allow a larger piece of bunghole buffer to be set on top, increasing the swept area of the filter, while also being less restrictive...and allowing even more air in. I could keep going, but I've already started to put myself to sleep. Best of luck on this development project, and remember to keep your thumb away from the filter...nobody likes a hole in their TP. Salutations from the southeastern Michigan swamplands.
Perfect coincidence. My budgies peaked their heads into our AC vents and chewed/destroyed the internal PP filter mesh. I was going to buy a new filter but now I'm thinking of sticking some layers of paper towels. Thank you.
For high air throughput it would be better with the large area concertina filter.
“You can always get it from your local supermarket”
March 2020 - “We’ll see about that”
I've seen carpentry workshops that use kitchen rolls for filters on the giant sawdust extractor vacuums. Far cheaper and just as effective.
Cheap and reasonably effective, but objectively not AS effective.
@@TonyRule For sawdust probably just as effective, only less effective on finer particles.
Found myself a new project 🤷 Having outdoor/indoor pets means dirt and dust on everything, and this seems like a good idea to me 👌
Like many people and yourself have figured out, an air void is a good thing. It is actually called an air plenum chamber. It equalises pressure, reduce sharp corners for the air stream and reduces noise. Bigger is better generally. As someone else has already stated he uses the disposable masks for the filter element. It is made with Polypropylene PP spunbound and melt-blown nonwoven fabric. You can also buy activated charcoal inserts for some types of masks. If you choose to use the disposable masks filter media, try to 3D print a mound on the intake side. This will spread out the folded pleats in the mask. More area equals less pressure drop and higher efficiency rate.
Excellent!
I had a vague idea like this some time ago, but it didn't get any further than salvaging some old computer fans. Now I'll have to actually build something! Paper tissues as filters are brilliant, that's a part I wasn't sure how to solve.
"They're always going to be available from your local supermarket..."
-Famous Last Words. ;-)
Awesome idea Clive. I know its off topic and all, but can you please do more of your old Trash Cooking? Me and the wife both love those videos!
Same
I was startled that there were week old comments on a 13 minute old video, but then I remembered Patreon existed
Ok good for you
@@Tejvir7 Congratulations! Your attempt at condescension has failed miserably!
i was also very confused thanks lol
If Patreon was on more platforms I’d use it but yeah I can’t afford Premium, direct channel support and Patreon
The Patrons already have the MK2 video with 3D files. Coming soon.
I've done this in bulk with your dollar store 20" box fan and standard furnace filters. Many choices of media. High throughput. Have to watch motor temps with the most restrictive. Still much cheaper than proprietary HEPA filters and scales to any area.
FEMA and other folks worked out the best improvised HEPA-grade air filter was pushing rolls of toilet paper through a solid baffle with holes cut into it. This was for fallout shelter purposes, so filtration of very fine particles was a criteria. You make many holes in a big baffle and put many rolls through the holes (they should fit tightly) in order to bring down the (parallel) resistance to flow. Still and all, a positive displacement pump or something with a lot of vacuum is required.
You can buy sheets of carbon or hepa filters cheaply for eBay and cut to size. That's what I use for my soldering fume extractor
I'd like to know if it does anything. The idea is great, but I'm not sure that small of an area will ever filter the air in a room... Will watch for updates!
It will do something for sure. If the air circulates in your room then eventually all of the air will pass through the filter. But will it effectively capture the dust from the air from the entire room? Not likely because some or perhaps most of the dust floating in the air will settle on some surface before it has a chance to go through the filter.
How much it will capture depends on the shape, size and air flow pattern of the room, the location and air flow of the filter and so on.
I have a ceiling fan in my living room so if I were to build something like this I would place it beneath the fan. Or maybe even hang it below it.
I would like to see the change in current draw with the different materials
On a slightly related note, you could change the paper when the power consumption reaches a set level.👍🏻
Hi, Clive.. I have recently built a wood lathe with the same style of air filtering for the motor and the electronics cooling. (PC fan + furnice filter fabric) The only difference in my version is, that i have made a much bigger "Filterbox"....to give me more filtersurface. The void in front of the fanblades helps to straighten the airflow. (...kind of flow straightener..) I like the toilet paper approach. Its so simple and ingenious...
I've been experimenting with this sort of thing a bit.
my main goal was to reduce dust, so after a few tests with different fabrics I bought a very fine steel mesh, which obviously won't filter any microscopic particles, but it also doesn't impede the airflow too much and it actually caught a considderable amount of dust each day.
one thing I noticed is that when the airflow is restricted too much the fans(mine anyway) tend to suck in air in the center of the exhaust side. This led me to the conclusion that it might hurt performance to have a void between the fan and filter, but I am still not unsure of what's the best way.
Final note, if you want to buy fans for this application, I would opt for "static pressure optimized" fans.
The void between the fan and filter will even out the lower pressure below filter over the whole surface. Also having the fan blades too close to the paper will cause cavitation, which will reduce fan efficiency, and create noise.
I think that your circular holes look great and I understand you've done them for aesthetic reasons although I do wonder about the total surface area being reduced?
Yes, the cross-sectional area of the fibrous filtration membrane, sorry, square of bog roll, is decreased by this. And, the only time you see the holes is when there's no filter. I see little point to form over function.
@@TonyRule Obviously, we need hexagons...
What if you made the top "void box" thing a cylinder that's taller with holes on the side so you can wrap some toilet paper around the outside increasing surface area and thusly airflow
Indeed, triple the height of the buffer, make the same barrier pattern in it and the filter area will be 5 times bigger. So you only have to renew the toilet paper once a week 😂
And as a bonus, you could design it so that it looked like a glowing roll of loo paper sitting in the corner of your room
That's starting to sound like the Blueair Blue air purifiers, which use cylindrical filters but with the fan on top. They claim the design makes placement consideration less of an issue as it's pulling in air from 360 degrees around the unit
@@AaronSmart.online sounds a bit more useful with permanent use. Exhausting up into the room makes the 'short circuit' recirculation less likely, especially if you have a bit of an exhaust duct too.
Fantastic idea! Really good for the home mycologist too, as running something like this in a room wood decrease the risk of contamination by mold spores, and also filter any oyster/lions main/etc spores which aren't to good to breath in too! fab idea! Thanks! 😃😃
Chamber between fan and filter: good idea. You are correct about it regulating the geometry of the air flow and using more of the paper. This in turn reduces the air resistance and increases the flow rate. It might be interesting to experiment with baffles to straighten out the air flow and reduce vorticity in the chamber, and possibly even ducting to direct the air out the sides after the fan.
I think the idea isn't so much that red light helps you sleep as blue light keeps you awake. That's why the night mode on your phone/monitor cuts it out.
red light is generally used when you need to preserve night vision, like while stargazing. Why night mode in star chart software is red only, and you can get red flashlights (or just put a red filter over a regular flashlight). It allows you to see what you're doing, but when you shut it off, your eyes don't have to re-adapt to the dark again.
Night mode on your phone/monitor is marketing wank.
Put an ionizer in it to attract patricles.
You need to add a built-in toilet paper feed so you can just pull a new square and tear off the old one.
no! a geared motor and a receiver spindle! reel to reel automatic changing!
Last year I made my own face masks. I tried various designs and they all worked to a greater or lesser extent. However, where possible I incorporated a HEPA filter as a 3rd inner layer and found that replaceable vacuum cleaner bags were a good source. In particular the Henry NVM-1CH Hepa-Flo were relatively cheap, square and big (other makes are available). I could cut 4 or 5 filters out of one bag. They have advantages over tissue in that they are made for the job and they are washable. The obvious downside is that cost a lot more than loo roll. They are considerably thicker than paper tissue, but we have had no difficulty breathing through them, so your fan should still work.
bonus thought: when you are talking about the pattern of holes at 10:00 - you can model a solid block and give it infill, walls, but no top or bottom layers in the slicer. this leaves the infill pattern exposed on the top and bottom. it can look amazing and would allow air to pass depending on the infill pattern used.
I'm surprised something like this has never took off as a home dust reducer. I can imagine your surfaces would stay cleaner
"Always be available from your local supermarket" in reference to toilet paper - has 2020 not taught us anything! :p
Haha, yeah, like... for some people, what a question mark is (?) and how to use one! 😉
It would look nicer with a grill over the paper.
The buffer/plenum is important. The longer the better, 1/2 to 2 times the cross section. The filter area needs to be increased 50 fold.
And still I think the system capacity is going to be disappointing. But, it's the fun of the build. Thank you for sharing what you do.
The plenum is a must do for optimum efficiency. As a rule of thumb, it should be 3 times the diameter of the fan away. I worked in industrial maintenance for many years and dealt with many contractors who installed air systems. Most all used that simple rule. It also applies downstream, before the duct takes a turn or size change.