Cylindrical air filter (for dust) to attach to fan?
August 4, 2022 2:39 PM   Subscribe

I want to use a small circular fan to filter dust, where can I search for a cylindrical filter suitable for the fan's dimensions? (details below)

I have a dust allergy, and despite regular cleaning (vacuuming, dusting, etc.) and covering my mattress and pillows with dust covers, my room seems noticeably dusty and I wake up in this room with lots of congestion. I noticed the difference when I slept somewhere else with central air recently and for only those few days had none of my normal symptoms - which immediately returned when I slept back at home again.

Anyway, I want an air purifier but don't have more than 100€ to spend on this project right now. I already have a 50W, 26cm diameter circular fan which I use in the room on warm days. There are many recommendations online for attaching filters in various configurations to square box fans, but less about circular fans. My first thought was to just buy a square filter that is 30x30 cm or so and attach it at intake end sealing it with tape as best I can. For possibly better performance, some people recommend creating a larger buffer intake area, which I could potentially do using cardboard to form some sort of extended cylindrical section to which I would then attach the filter at the end. It then occurred to me.. I can just buy a cylindrical air filter and directly attach this at the intake end, and place some cardboard over the other end. It seems many purifier models actually use cylindrical air filters. My main problem is that as I search for these filters, they rarely provide dimensions - they assume you're just going to throw it in whichever machine they're associated with.

So - can anyone help me find a cylindrical air filter with a diameter around 26cm? Or even point me to the sites which will provide filters with detailed dimensions? The inner diameter must be 26cm or less, and outer diameter should be greater than 26cm. I'm located in Germany, which possibly makes things more difficult.
posted by unid41 to Home & Garden (6 answers total)
For a hundred Euros I think you should just buy an air filter! It will work better and be less hassle. I have a great Levoit one that was only about $110 Canadian which is well under $100 Euros.
posted by nouvelle-personne at 2:54 PM on August 4 [2 favorites]

Definitely look into getting a real air filter. Your fan’s motor wasn’t build to deal with the additional resistance of a filter, and will very likely burn out prematurely because of it.
posted by a box and a stick and a string and a bear at 3:48 PM on August 4 [1 favorite]

I think if your fan was wider it might make sense to use it with an air filter, as the current dimensions don't strike me as a useful tool to filter out the room (not knowing the size of course).

However, if you still want to go ahead, the form factor is still an issue here because the sealing part won't be resolved adequately to be of use to you.

My suggestion to you if you still think budget-wise an air purifier is still out of the question, is to make a square housing for your fan + filter combo, per the instructions you've found. This one you can work backwards to establish the dimensions with the filters you can buy.

But if you can, there are decent ones under €100 which is basically the same DIY square fans setup but with a plastic housing, like this (Amazon DE link) and its coverage is about 50m² space.
posted by cendawanita at 1:43 AM on August 5

If it helps your thinking, a local mall used an earlier design that was more prevalent here in all their lifts (they bolted it up on the ceiling) and i use one for my room.
posted by cendawanita at 1:46 AM on August 5

A shopvac filter might work for your situation. You'll probably have to build some sort of cardboard plenum/duct/adapter. You'll need to make sure that it's easier for your fan to pull through the filter, rather than around the outside of where the filter is attached to the fan. Use smoke (cigarette, incense, whatever) to track where the air is being pulled in.
posted by donpardo at 9:41 AM on August 5

I agree that you would probably be better off buying a well regarded air purifier with a high CADR (clean air delivery rate). The Levoit Core 300 is good for a 20 square meter room for allergies (5 air changes per hour).

If you really want to DIY there's an example here of a circular fan used with a bucket. The bucket and lid basically provide the structure.
posted by oneirodynia at 12:15 AM on August 7 [1 favorite]

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