Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Smart Air

smartairfilters.com

Post reply on HN
Print view View original

61–70 of 95 posts

Re: Smart Air

#61

Post by Goopplesoft »

eru wrote: post #58
dmix wrote: post #40

Earlier quoted context omitted.

Negative ionic air purifiers may help with SAD (seasonal depression) [1] similar to daylight bulbs. Research is somewhat inconclusive. It also supposedly makes air have equivalent ionic levels to "country or mountain air". Apparently in the city/offices the ion levels in the air are quite lower than in rural areas which is harmful. This of course is the sales pitch from the companies selling them. But at the same tim…

Why is killing bacteria always good?

Ah the perils of text language. You're not sure if he's referring to both bacteria and pet dander or just pet dander.

Re: Smart Air

#62

Post by icelancer »

jmpe wrote: post #11

I've used HEPA filters when I built an IV glove box a couple of years back. Don't recall the numbers, but I needed a fair bit of pressure from the air pump to get a decent flow rate. Somehow I don't think a fan will do it.

Did you even read the data that shows otherwise?

Re: Smart Air

#63

Post by seanmcdirmid »

malandrew wrote: post #47
DanBC wrote: post #43

Earlier quoted context omitted.

What about it depresses you? The fact that people need air filters? Or something about the way these people are doing it? I really like their website. They're open and honest about not being experts, and about how they do things, and how they want corrections and additional information. They sell you a kit if you want it , but they make no secret about it being really easy to do by yourself.

It's a classic case of negative externalities caused by stupid human decisions and a complete disregard for the commons. People have been shitting in the commons so long in Beijing that the particulates in the air are crazy high. Everyone feels like this have to have a car instead of pushing hard for effective public transportation. Since everyone has to have a car, it hurts everyone on buses because the traffic is s…

Beijing is the victim of geography where pollution is often trapped in an inversion; a problem like Salt Lake City in the states. Beijing has much fewer cars per person than say Seattle, and the problems arise from too many people more than too many cars, coupled with shitty cheap oil refined poorly leads to a huge problem in aggregate. On the other hand, the subway system has been built up nicely, and is expanding very quickly, though it is always wicked full and not very comfortable by western standards. Beijing's traffic problems simply boil down to too many people and cars and not enough road with nowhere really to build more.

Old coal boilers are another problem, and a lot of pollution blows in from the Hebei country side and gets stuck in Beijing without an outlet. All buildings in Beijing are heated by the city, so it's not even the building owner's option to be more efficient. Beijing is slowly switching over to natural gas for heating but the transition will take a couple years to finish.

The AQI right now is down to 50 where it was 340 only a few hours ago. I can only imagine we got some wind to blow out the bad air all of a sudden.

Re: Smart Air

#64

Post by seanmcdirmid »

lignuist wrote: post #29
X4 wrote: post #14

I think that people in Beijing and other Asian or American countries should stand up more often and force their governments to install filters on each fabric's smoke pipe and charge those who don't comply with a big fine. You can then open a petition that votes for using the money generated from that fine to for deploying fuel-less car alternatives… Come on, tell me you're helpless and dependent on your government an…

While I agree in general, one of the biggest sources (if not the biggest) of dust in Beijing's air is the desert Gobi. It will be pretty hard to build an appropriate filter. ;) In my experience Beijing's air is really "special". Hot, humid, dusty. Not my favorite environment.

The dust is not as bad these days as 10 years ago; the tree planting in Inner Mongolia and hebei has worked surprisingly well. These days, pollution from artificial sources is a much bigger problem and we've mostly forgotten about dust, but sand storms still occur occasionally.

Re: Smart Air

#66

Post by lostlogin »

jmpe wrote: post #12
ksec wrote: post #9

I am actually looking for a solution where the filtering is done through water rather then a HEPA filter, which needs replacing quite a lot in a environment as bad as Bejing.

Use aquarium air stones. The smaller the bubbles and higher the column of water the better.

Wonder if a fully functioning fish take would be even better - if you get plenty of plants growing, they will feed off the water/each other in my experience. The rate of air injection would likely have to be higher than that of a normal fish tank though? I used to run a fish tank with CO2 injection to get the plants growing well. The best, cheap way of doing this was to put CO2 into the filter intake, that way big bubbles which escapes the diffuser were blended up by the impeller of the filtration.

Re: Smart Air

#67

Post by krunk4ever »

Pretty cool idea, but given that the target audience are people living in China, why is the site in English instead of Chinese? Is the target Americans or other English speaking people living in China?

Re: Smart Air

#68

Post by chopin »

Axial fans, especially those for household purposes do not offer the required pressure drop of approx. 300 Pa (https://en.wikipedia.org/wiki/HEPA#Specifications). Axial fans have typically a high throughput but low max pressure difference (see eg. http://www.adrianagarcia.me/wp-content/themes/twentyeleven/a...). HEPA filters require radial (or centrifugal) fans for acceptable throughput.

As well, a HEPA filter becomes clogged very rapidly without appropriate prefilter. This means that the pressure drop required increases considerably definitely beyond reach of any household fan.

Re: Smart Air

#69

Post by chopin »

icelancer wrote: post #62
jmpe wrote: post #11

I've used HEPA filters when I built an IV glove box a couple of years back. Don't recall the numbers, but I needed a fair bit of pressure from the air pump to get a decent flow rate. Somehow I don't think a fan will do it.

Did you even read the data that shows otherwise?

Did you even bother to look up basics of HEPA filters? They require an initial pressure drop of 300 Pa (https://en.wikipedia.org/wiki/HEPA#Specifications), which is beyond reach of any household fan. When the filter bcomes clogged, the pressure drop will increase even higher.

Updated: Grammar

Re: Smart Air

#70

Post by luke_s »

This is good, but why is it in English, not Chinese? If you want to reach people wouldn't the best way be to post on the various forums netizens like to hang out in?
Post reply on HN