141–150 of 178 posts
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You may wish to use a cheap thin washable pre-filter either way. It will catch a lot of the hair before it hits the fine filtration, which you can then just wash off the pre-filter, making it easier and cheaper to maintain.
Do you have a link to one of the cheap thin washable pre-filters that I can look at as a reference for what to buy?
You could probably buy a box fan and tape a HEPA filter in front.
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> Lungs of a person act as a perfect purifier. Is that good? I mean, of course it's good that PM doesn't just pass straight into our bloodstream, but isn't our lungs doing the purifying exactly the thing that people try to avoid with mechanical air purifiers?
The whole point of filtering air for PMs is to avoid having them in your lungs so I'm pretty sure that's not "good".
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Being able to detect particulates in the air isn't what's important. You need to know if it's actually improving the air quality.
If you're referring to "air quality" in the form of particulates… it does turn off after a while. 15-30 minutes after cooking, one or two after sweeping, etc. Presumably it's triggered by no longer detecting particulates in the air, one would have to be fairly conspiracy-minded to suggest that it's working on some kind of timer (and can tell the difference between dust-timeouts and gas range waste timeouts)… I figure…
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> it provides a static pressure of 7.63 mmH2O If anyone else is wondering, that's about 0.8 mbar (roughly 8 ten-thousands of an atmosphere), or 80 Pa of over-pressure. To put this into perspective, my local atmospheric pressure varied about 2000 Pa in the last 48h due to weather changes.
Lemme go send my air intake through a time machine and as long as the weather keeps changing we can use that to drive air through a filter!
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> Because they are designed to be quiet and still provide good flow of air they produce almost no pressure differential to speak of and the flow can be halved by a wire mesh that is a bit too dense There are high static pressure fans which address this problem, specifically designed to work with pressure differential, usually used to blow air through radiators for water cooling. The fan linked in the github page (Noc…
> it provides a static pressure of 7.63 mmH2O If anyone else is wondering, that's about 0.8 mbar (roughly 8 ten-thousands of an atmosphere), or 80 Pa of over-pressure. To put this into perspective, my local atmospheric pressure varied about 2000 Pa in the last 48h due to weather changes.
Car tire pressure is about 1.8-2.5 Bar.
Your 2000 Pa atmospheric pressure change is about 20 mBar.
Pressure in an inflated balloon is about 2 mBar (0.002 Bar).
Noctua's static pressure is 0.8 mBar. Let's call it 0.5 mBar dynamic working pressure.
Not as low as I expected. Not sure if it will have a semi-reasonable speed, but that will definitely push some air.
Another comparison, 0.5 mBar is 50 Pa = 50 N/m². That gives about 50 * 0.3 * 0.3 / 10 ~ 0.5 kg force on a 30x30 cm² surface.
Finally, as the article video and data shows, it does actually work.
[1] http://scipp.ucsc.edu/outreach/balloon/labs/InflationExp.htm
I don't know how effective they are compared to these devices, but I much prefer to keep plants with air purifying qualities. NASA did a study on a variety of air purifying plants in 1989: https://ntrs.nasa.gov/search.jsp?R=19930073077
Last time I checked, most of those aren't safe for house pets either :/
i don't think they make much difference for air quality, but i bought some "air purifying" plants and cross-checked them against the aspca list for safety:
https://www.aspca.org/pet-care/animal-poison-control
(my cat likes to munch on my spider plants, even with cat grass available)
https://www.eventbrite.com.au/e/making-your-home-smoke-proof...
Materials for DIY Air Purifiers are:
- Floor Fan of any variety (BYO or we will be providing options for large and small fans)
- PM2.5-suitable Air filter (we will be bulk ordering the best type of Ryco MicroShield Cabin Filters for this purpose)
- Carboard & tape (we will provide these materials)
Efficiency of the US-based version seems to be quite good:
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If you want this to actually work, you take a box fan, and 2 filters. You make a triangle and then some cardboard on the top and bottom to fill the gap. This increases surface area and reduces the stress on the fan due to pressure drop. Slapping a filter directly on to the box fan is going to kill the fan very quickly. https://i.imgur.com/SX1RloH.jpg
Or ditch the cardboard, and use 5 square HVAC filters to make a true "box fan".
Cardboard is the vastly more cost-effective option. And taping a HEPA filter directly to the back of the fan effective and proven.
Do air purifiers really work? I always have impression they're just sham, or at least placebo.
Yes they do. But you need a sufficiently powerful one to be able to circulate the air in the room enough times per hour, more that the circulation that occurs through the doors, windows and even walls. Eco-rated houses have a circulation of about 2-3 times per hour. Older houses that are well insulated are about 5-6 times per hour. The purifier needs to be powerfull enough to spin the entire air volume couple of time…
You're not talking about HVAC, are you?
Nevertheless, I do know people living in leaky homes/building, and they do get >1 exchange/hour.