How effective is an organic vapor cartridge, as in masks for paint
On 2020-04-11 11:37, Davej wrote:
On Friday, April 10, 2020 at 2:38:34 PM UTC-5, Phil Hobbs wrote:
On 2020-04-10 09:55, Davej wrote:
On Thursday, April 9, 2020 at 11:10:23 AM UTC-5, Phil Hobbs wrote:
On 2020-04-09 11:56, Davej wrote:
Only good for 95% of particles larger than 0.3 uM. How about a
mask where you breathe through a chamber containing a sterilizing
UV lamp or percolating through some sort of fluid? How do the
military surplus NBC filters compare to the N/P95/99/100?
This article that James posted in the other thread is illuminating
on the properties of N95/N99 masks. For instance, I wouldn't have
guessed that alcohol will depolarize the electret filter layer.
Ooh, how about a powered electrostatic filter?
Electrostatic precipitators are used quite extensively. At one time you
could put them on your hot air furnace. Unfortunately they tend to
generate a fair bit of ozone, which is not a good thing to be breathing
and is also hard on the stuff in your house. In an industrial setting
(e.g. as part of a stack scrubber) it doesn't matter much because the
ozone is highly diluted and dissociates pretty fast (a few weeks). In a
recirculating system the concentration is higher and it's what you're
breathing all the time.
I am curious how the N95 uses a critical electrostatic charge in that
nasty fuzzy material while the round pink P100 filters look like a
totally different design.
From a classical physics POV, one would expect electrets not to work.
An object with a frozen-in charge imbalance or dielectric polarization
should attract surface charge until the field outside it is neutralized.
This is true in the far field. Closer to the surface, though, say
within 100 um, you still see the field. This turns out to be because in
a solid-state physics POV, there aren't enough available surface states
to balance out the frozen-in field. So if you configure them correctly,
e.g. in spun fibre form, you can make the equivalent of an electrostatic
precipitator.
Cheers
Phil Hobbs
Is this internal charge scheme then also the mechanism for HEPA
vacuum bags? There has been controversy regarding their use for
mask filters.
https://www.youtube.com/watch?v=vmYt_wtaLCk
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7108646/
Dunno. The effect has been used for air filtering since the '70s that I
know about.
Dr. David Price, an ICU pulmanologist of Weill Cornell Medical Center in
NYC, has a very encouraging video about precautions. It's a recorded
Zoom conference from a couple of weeks ago, so it's a bit rambling, but
we all have lots of time on our hands at the moment.
https://www.youtube.com/watch?v=7Wr9Z_enNQ4
The tl;dr is that the vast bulk of cases are transmitted by sustained
close contact with somebody showing symptoms (or who will show them
within a couple of days), followed by touching your face. He says we
all have to become "hand nazis".
.