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Should our desert communities make water from air? The Consumer You: Marketplace

Started 6/30/21 by Showtalk; 11334 views.

Msg 98 of 106 to Showtalkshowtalk

In reply toRe: msg 97

From: $1,661.87 in cats (ROCKETMAN_S)

8/13/21

Showtalk said:
I don’t think masks actually stop the virus, I think they remind people to distance. People in masks who are face to face are not distancing.

There's definitely a behavioral reinforcement mechanism going on by wearing masks. I notice that wearing a mask keeps all sorts of people and their cooties away from me.

While they don't truly stop naked viruses, the particles in which they ride are going to be wet, and they are much larger than the viruses, larger than the fiber spacing on a good non-woven mask or a microfiber cloth insert.

The droplets are grabbed by capillary action when they touch a properly designed mask, which also catches the viruses within.

Evidently a dry virus begins to deteriorate surprisingly fast even though it may remain suspended for hours due to Brownian molecular motion, since at such a tiny scale these forces are much more prominent than the effects of gravity.

But the real effect of masks is they stop outgoing particles quite nicely. Not all of them. It is like radio signal strength or audio levels - you measure the attenuation in decibels, which is a logarithmic scale.

So 3 decibels are a 50% reduction, and 6 decibels are a 75% reduction, and 10 decibels are a 90% reduction.

So if there's a 10 dB particle attenuation with the mask, that has gotten rid of 90% of the particles.

20 dB is 99% reduction. 30 dB is only 1 in 1,000. 40 dB lets through 1 in 10,000.

generally, somewhere between 30 and 40 dB is close to the practical limit of any affordable filtering / mask technique until you get to some truly exotic systems that really have finer sieve channels than the virus particles, which involves the kind of manufacturing techniques you see in the semiconductor industry.

Speaking of sieves, I got to see a molecular sieve at an industrial show a few years back that is used to separate oxygen and nitrogen from the air. It also isn't 100% effective, but you get something like 98% nitrogen and argon instead of 78% with 21% oxygen from unprocessed air

For most industrial processes, 98% nitrogen and less than 2% oxygen is sufficient to prevent unwanted oxidation in the process, although not as inert of an atmosphere as, say, a pure helium purged environment. So you can handle a lot of things that would otherwise have serious corrosion problems.