Air purifier?

[chuanz]

Ok, while riding my bike just now breathing in today's relatively cleaner air, I realized there's a flaw in my calculations.

H10 85% is based on MPPS of 0.3um particles, which are included in PM2.5, but slightly less than a magnitude smaller. For larger particle size, up to 2.5um, the filtration efficiency is higher.

What this means is the calculation above is worst case scenario. Which means u'd get "Good" air in lesser than 30 mins with H10.

 

[WussRedXLi]

HDB room size say, 4m x 4m x 3m (?) = 48m3.
At max setting for A28E, you are looking at 3.5 air change per hour. Based on the table above, air is practically "Good" after 30 mins, and there is probably no practical diff after 1 hr.

Excellent info. Yrs it is around there.

Samsung AX40...max speed. V small PC room of 4.x times 3mx metres. Got wardrobe and cabinets taking up more volume.

PM2.5 monitor shows good air after 5 to 10 mins nia. Together with aircon to mix the air up.

 

[WussRedXLi]

With yesterday's haze...i made another interesting observation.

Room is cleaned by air purifier. Verified clean with pm2.5 monitor.
Moved air purifier out. Closed door and windows. Windspeed 9kph on wunderground.com and yeah got wind in living room. My windows actually got rubber gasket...but i did move in and out of the room a few times.

3hrs later, measure room with pm2.5 monitor. Air quality just a bit better than living room nia.

Conclusion : closing windows/doors/switching on AC does not help much with regards to pm2m5. It may help with the smell though.

 

[WussRedXLi]

H10 85% is based on MPPS of 0.3um particles, which are included in PM2.5, but slightly less than a magnitude smaller. For larger particle size, up to 2.5um, the filtration efficiency is higher.

What this means is the calculation above is worst case scenario. Which means u'd get "Good" air in lesser than 30 mins with H10.

Haze particles are usually 1 microns and below. They go down to approx 0.02 to 0.05 microns. Indon haze 90% is below 2.5 microns.

I'll try to dig out the particle size distribution later, but thats based on China haze.

 

[stam]

is the "Plasmacluster" really useful?

 

[tmkedmw]

...
Conclusion : closing windows/doors/switching on AC does not help much with regards to pm2m5. It may help with the smell though.

Good that u validated. Aircon have filter but they are ineffective against pm2.5.

 

[WussRedXLi]

All regions pm2.5 concentration slowly inching up. See Chuanz's graph on neocities.

 

[jimboyboy]

Conclusion : closing windows/doors/switching on AC does not help much with regards to pm2m5. It may help with the smell though.

So does it mean that an air purifier can still work inside a room without air-con?

What about those who don't have any air-con in their apartment? Is it ok for them to leave a tiny gap at the window while they on the air purifier? Or better for them not to get air purifier but use masks instead?

 

[tanahgu]

hi

is the a28 useful if i do not have air con and like to keep 1/4 window for hdb bedroom (otherwise too warm)?

or do i need a more powerful purifier?

thanks

added: me asked similar question as jimboyboy

 

[WussRedXLi]

Good that u validated. Aircon have filter but they are ineffective against pm2.5.

Yep.... Just realised that i am able to have 9.5 air changes per hour with the Samsung AX40 in my room.

SGH burns unit standard is 20 ACH.

 

[matrix05]

Good that u validated. Aircon have filter but they are ineffective against pm2.5.

The a/c indoor unit is like a horizontal tower fans. It does not introduce exterior air from outside but cool & circulate air that is already in the room. If you put a pcs of hepa filter behind the a/c's filter, it will act like a air purifier.
Any taobao hepa filter expert here can recommend a filter?

 

[chuanz]

The a/c indoor unit is like a horizontal tower fans. It does not introduce exterior air from outside but cool & circulate air that is already in the room. If you put a pcs of hepa filter behind the a/c's filter, it will act like a air purifier.
Any taobao hepa filter expert here can recommend a filter?

Pls don't put a HEPA on your FCU... u're gonna kill it due to the pressure required to draw air across HEPA... those 3M electrostatic filter designed to put on FCU also got ppl advise against it liao.

 

[chuanz]

Should I include the 3-hr PSI? (since I see WussRedXLi always mention together with concentration reading )
or making the chart too crowded/hard to read?

[img scrapped]
(due to Google Charts restriction, multi-line legend can only go on top for dual-axes charts)

 

[WussRedXLi]

Should I include the 3-hr PSI? (since I see WussRedXLi always mention together with concentration reading )
or making the chart too crowded/hard to read?

I think better not. Coz PSI is an index, AQI is also an index. And they are much higher than than concentration ug/m3 units. Will just confuse the general folks if we put it into the graph.

 

[WussRedXLi]

So does it mean that an air purifier can still work inside a room without air-con?

What about those who don't have any air-con in their apartment? Is it ok for them to leave a tiny gap at the window while they on the air purifier? Or better for them not to get air purifier but use masks instead?

hi

is the a28 useful if i do not have air con and like to keep 1/4 window for hdb bedroom (otherwise too warm)?

or do i need a more powerful purifier?

thanks

added: me asked similar question as jimboyboy

My experience is that if you can only leave either the window(s) or door open. ie windows opened/door closed OR windows closed/door open.

That'd would work alright with concentrations ug/m3 below 200 ug/m3 AND ACH (Air Change per Hour) of air purifier is above 5.

I have done that > 15 days/nites for Aug 31 - Oct 6.

 

[WussRedXLi]

Ie. You cannot leave an open gap for the windows or door. In fact if its windy, you would need to plug up the door gap below.

It wont be hot if the air purifier output is blowing at you when you are at the PC. Sleeping is another story though.

 

[bullfrog]

Yeah. If you allow outside air in, then it would defeat the purpose of cleaning the air inside . Just close all doors and windows like how you would if you had an aircon and let the purifier clean the air in your room.

 

[tmkedmw]

My experience is that if you can only leave either the window(s) or door open. ie windows opened/door closed OR windows closed/door open.

That'd would work alright with concentrations ug/m3 below 200 ug/m3 AND ACH (Air Change per Hour) of air purifier is above 5.

I have done that > 15 days/nites for Aug 31 - Oct 6.

Yes. U put your particle counter to good use, ie validate the cleanliness of air with various permutations.

This shows that for those without air-con, buy a oversize air purifier relative to the room size, so that u achieve a high ACH, ideally greater than ACH of 6. (ACH of 6 is 6 air changes per hour, ie the air purifier takes in the dirty air, cleans it, and then output "cleaned air". It cleans the whole volume of air in your room 6 times in 1 hour).

It can also be for those who are budget conscious and do not want to on your aircon for extended periods of time.

Your mileage may vary especially if u have strong winds blowing thru' your windows that bring in dirty air rapidly.

 

[tmkedmw]

Should I include the 3-hr PSI? (since I see WussRedXLi always mention together with concentration reading )
or making the chart too crowded/hard to read?

*mock up only*

(due to Google Charts restriction, multi-line legend can only go on top for dual-axes charts)

Don't use another Y axis for the 3hr PSI.
Use instead the horizontal limit lines for v. unhealthy, unhealthy, unhealthy for sensitive, etc .... as your y-axis markers for the 3hr PSI.

0 - 50 Good
51 - 100 Moderate
101 - 200 Unhealthy
201 - 300 Very unhealthy
Above 300 Hazardous

So, if u have a PSI reading of say 75, plot it midway betn the moderate and unhealthy limit lines.
In that way, u need not have another Y axis.

Just an idea, don't know how feasible to do that in google charts though.

This composite chart will actually show how much the 3hr PSI lags behind the 1hr pm2.5 readings wrt different health band limits, and thus show how inadequate the 3hr PSI numbers are for people to react to haze conditions.

 

[chuanz]

scrapped that idea... too complex and will confuse the nuts out of ppl.. coz then you'd have a PSI chart that doesn't read as PSI... lol