Do air purifiers that function like bongs exist?
October 20, 2008 8:15 PM   Subscribe

I prefer products that don't require replacement parts (e.g. gadgets with rechargeable batteries, bagless vacuum cleaners, etc.). I'm currently in the market for an air filter, but they all require replacement filters, and I can't find one that operates on the same principle as a bong. Do such magical appliances exist? Is there a good reason why they shouldn't?
posted by marclar to Home & Garden (9 answers total) 2 users marked this as a favorite
Bubbling air through water only works if the airflow is slow, so that the bubbles are small and have a relatively large surface area per unit volume.

Also, a bong doesn't really filter the air all that well. (If it did, no smoke would get through.)
posted by Class Goat at 8:22 PM on October 20, 2008

Best answer: I heard or read, somewhere, about an air purifier system that worked by increasing the humidity in the air until rain drops formed around the dust particles suspended in it, thus pulling them out of the air ... but it was in the context of large-building HVAC, nothing for home use.

I agree with Class Goat; I don't think that bubbling air through water filters it significantly, or at least not well enough to make it worthwhile as a filtration medium.

Depending on what you are trying to filter out (what particulate size), you may be able to use some type of filter with a cartridge that can be washed or vacuumed periodically. Typically these filters work better for large dust particles. E.g., shop filters for pulling sawdust and drywall dust out of the air are almost always washable or vacuumable, and some household furnace filters made to grab big chunks of dust and hair are, but most true HEPA filters aren't.

Some household air filters have elements that are washable and whose only disposable component is the odor-absorbing charcoal part. If you can live without the odor-absorbing ability, these can last quite a while. Generally they are not HEPA rated, though.

Then there are the "ionic breeze" type "filters" which have no consumable parts, but depending on who you ask they do either very little, nothing, or less than nothing (i.e. fill your house with ozone for no gain).

Personally I'd recommend the kind of air filter I use in my house ... which is partly disposable, but it's very cheap. Basically get a regular size box fan, and a 20" furnace filter of your choice. If you want basic shop dust removal, a fiberglass one is fine, or you can go up as far as the "True HEPA" ones. Bungee cord the filter to the back of the fan. Use duct tape around the edges to seal. Place fan in room, turn on fan. Replace when filter looks dirty. I do this, with 3M filters that are about $3/ea. Does wonders for my allergies and it's cheaper than anything else I've found or devised.
posted by Kadin2048 at 8:45 PM on October 20, 2008

Personally I would rather deal with filter replacement than bong water. Maybe that's just me. But if you want to play with using bubbles to filter your air, perhaps you could just buy a bunch of fishtank air pumps, an air stone for each one, and a bucket.

The right way to filter air without using any kind of replaceable filter element (even a liquid one) is with a cyclone. But they're noisy. More here.
posted by flabdablet at 8:47 PM on October 20, 2008

I'm not sure which kind of air filter you are looking for, but I'd be surprised if there wasn't a version of it that uses an electrostatic filter that can be washed out.
posted by ssg at 9:01 PM on October 20, 2008

Something to consider about using water as your filtration element - mold is a big problem with houses today. The reason is, we've sealed our houses against the elements (those of us not rehabbing a 90-year-old leaks-like-a-sieve house anyway) but our living there is like dumping five gallons of water on the floor every day (from breathing, sweating, cooking, bathing, etc.).

Bubbling dry air through water is going to add water. Then, when that air gets some place colder (like inside your walls) that water is going to condense. Pretty soon you're in mold hell.
posted by Kid Charlemagne at 11:40 PM on October 20, 2008

not sure what your purpose is (not stated!) ... but an oil bath air filter (as was supplied on old volkswagen beetle engines ... on top of the carburettor) merely needs to be regularly cleaned and re-oiled! no replacement parts ...

So, yes ...they do exist ... not sure if they exist for your required application though!
posted by jannw at 2:31 AM on October 21, 2008

Water is a less efficient medium to pull dust through than air, simply because water is a shitload heavier than air. Remember how hard you have to pull on a bong? I know, not very hard, but still, it's a heck of a lot harder than just breathing, right?

You can get air filters that can be cleaned out to a certain extent. For extremely fine particulate matter like dust or smoke, you'll probably wind up using a medium like activated charcoal--you can't clean that, by the way. I mean, technically you can, but you'll need a super fine-mesh screen to separate the bad dirt from the good dirt. Really, just save yourself a bunch of time and forget about the idea of a 100% reusable filter. The closer to 100% reusability you get the further you get from 100% non-sucky.

I've gone through dozens of air filters and tried, bought and returned every kind of air filter technology. Except for the last one I purchased about three years ago. That one's still working. It cost approximately $800, and can be used in a hospital or a clean room.

If you want an air filter that actually works, you need to resign yourself to replaceable filters. Not only that, but expensive ones. We used ours for a single room--but that was the "smoking" room and we have two cats as well. The filter I purchased has three primary stages. The first stage will catch all the large crap like hair or dirt--this stage can be easily cleaned. The second stage is activated charcoal, and the third stage is basically for odor and gasses. Neither of those stages are replaceable. Each replacement lasts about a quarter of the year, but I don't change mine as often as I should so it's more like half.
posted by Civil_Disobedient at 3:35 AM on October 21, 2008

Best answer: The Venta Airwasher sounds like what you're looking for. But you have to wash the tank. Pricewise, they're about the same as some of the high-end HEPA filters.
posted by fiercekitten at 9:27 AM on October 21, 2008

Response by poster: Wow -- great responses; thank you.

For the time being, I'm going to try the DIY box fan approach. Good recommendation, Kadin2048.

Once I have the funds, I'll get a Venta Airwasher. That sounds right on the money; thank you, fiercekitten.

(Although I kind of want to build a super-bong multi-chamber air filtration system for the hell of it. I like the idea of tubes and bubbles percolating around my house.)
posted by marclar at 4:25 PM on October 21, 2008

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