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Experiments on a $50 DIY air purifier that takes 30s to assemble

dyno-might.github.io

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Re: Experiments on a $50 DIY air purifier that takes 30s to assemble

#21

Post by ahaucnx »

We have open source, open hardware build instructions for a very reliable Air quality sensor that can be used to measure PM2.5 and also CO2.

https://www.airgradient.com/diy/

We have tested it extensively and it is very accurate for the fraction of the costs of commercial sensors. You can build it for less than USD 20 and send the data to our cloud server or any other backend.

We also measure CO2 because if you have purifiers running you often do not have enough fresh air ventilation and your CO2 often gets very high (often >1500ppm) causing headaches and reduce cognitive performance.

We measured this in classrooms some time ago and the results were not very good.

Details. https://www.airgradient.com/blog/2020/02/07/we-measured-the-...

Re: Experiments on a $50 DIY air purifier that takes 30s to assemble

#23

Post by azmodeus »

ahaucnx wrote: post #21

We have open source, open hardware build instructions for a very reliable Air quality sensor that can be used to measure PM2.5 and also CO2. https://www.airgradient.com/diy/ We have tested it extensively and it is very accurate for the fraction of the costs of commercial sensors. You can build it for less than USD 20 and send the data to our cloud server or any other backend. We also measure CO2 because if you have p…

It would be nice if preassembled kits could be purchased from you. I would be happy to pay USD 40 for a good preassembled kit.

Re: Experiments on a $50 DIY air purifier that takes 30s to assemble

#24

Post by ddeck »

xiphias2 wrote: post #18
cyounkins wrote: post #6

Earlier quoted context omitted.

Most things that smell are very very small particles not captured by even HEPA filters and require a different kind of filtration. Most commonly activated carbon is used, either as granule or deposited on fibers.

I don't know any way to filter NO2 effectively from air, and I have tried practically all commercial air filters with the largest carbon filters on the market. The worst parts of air pollution cannot be filtered out without industrial devices (that are part of the air filteration system) as far as I know.

NO2 and other acidic gases are typically filtered using activated alumina balls impregnated with an oxidizing agent such as potassium permanganate or sodium permanganate.

There are residential air purifiers available that use this in combination with activated carbon for their gas stage.

Re: Experiments on a $50 DIY air purifier that takes 30s to assemble

#26

Post by headmelted »

azmodeus wrote: post #23
ahaucnx wrote: post #21

We have open source, open hardware build instructions for a very reliable Air quality sensor that can be used to measure PM2.5 and also CO2. https://www.airgradient.com/diy/ We have tested it extensively and it is very accurate for the fraction of the costs of commercial sensors. You can build it for less than USD 20 and send the data to our cloud server or any other backend. We also measure CO2 because if you have p…

It would be nice if preassembled kits could be purchased from you. I would be happy to pay USD 40 for a good preassembled kit.

This. I no longer have access to a soldering iron and want a bunch of these, not enough that it's worth the cost of buying equipment and the time spent making them.

Help us give you money! :-)

Re: Experiments on a $50 DIY air purifier that takes 30s to assemble

#27

Post by cinntaile »

azmodeus wrote: post #23
ahaucnx wrote: post #21

We have open source, open hardware build instructions for a very reliable Air quality sensor that can be used to measure PM2.5 and also CO2. https://www.airgradient.com/diy/ We have tested it extensively and it is very accurate for the fraction of the costs of commercial sensors. You can build it for less than USD 20 and send the data to our cloud server or any other backend. We also measure CO2 because if you have p…

It would be nice if preassembled kits could be purchased from you. I would be happy to pay USD 40 for a good preassembled kit.

The BOM already costs more than USD 40 so USD 80 is probably a more realistic number for a preassembled kit.

Re: Experiments on a $50 DIY air purifier that takes 30s to assemble

#28

Post by ddeck »

jansan wrote: post #22

This is certainly done with COVID-19 in mind. Is there any source that shows how effective HEPA filters are for filtering SARS-CoV-2, given that its average size is just 130nm, which is twenty times smaller than PM2.5.

HEPA is a bit of a loose term. It generally means 99.97% efficiency for 0.3 micron sized particles at some particular airflow.

0.3 micron was chosen because as noted by another commenter below, high efficiency filters typically filter better at smaller sizes than this.

A more stringent certification is EN1822, which first tests which particle size penetrates the filter the most, and then rates the efficiency based on that particle size.

With respect to viruses, a minimum of EN1822 H14 is required for use in European biological safety cabinets. An H14 filter is 99.995% efficient as it's most penetrating particle size (MPPS).

That said, it's important to realize the difference between using a filter to pass air into/out of a clean environment (e.g positive/negative pressure clean room) versus just using an air purifier in a room. In the latter case, the machine is only going to filter the air going through it, and will take a significant amount of time to turn over the air in the room, during which time it's just blowing things around.

Re: Experiments on a $50 DIY air purifier that takes 30s to assemble

#30

Post by dmitriid »

azmodeus wrote: post #23
ahaucnx wrote: post #21

We have open source, open hardware build instructions for a very reliable Air quality sensor that can be used to measure PM2.5 and also CO2. https://www.airgradient.com/diy/ We have tested it extensively and it is very accurate for the fraction of the costs of commercial sensors. You can build it for less than USD 20 and send the data to our cloud server or any other backend. We also measure CO2 because if you have p…

It would be nice if preassembled kits could be purchased from you. I would be happy to pay USD 40 for a good preassembled kit.

Once you start assembling and selling these, you'll quickly realise why many things are priced the way they are.

Especially low-volume tings like "pre-assembled DIY kits"

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