Electronics > Projects, Designs, and Technical Stuff

COVID-19 Emergency - Using UV Lamps to sanitize Face Masks overnight

<< < (20/27) > >>

profdc9:
If there are any references for UV mercury germicidal lamp efficiency, please send them may way.  The study I was referring to is

Hao & Han, Qiuyi & Zhang, Shanduan. (2013). “254 nm Radiant Efficiency of High Output Low Pressure Mercury Discharge Lamps with Neon-Argon Buffer Gas” Applied Mechanics and Materials. 325-326. 409-412. 10.4028/www.scientific.net/AMM.325-326.409.

That is where I obtained by 30% estimate from.




LaserSteve:
This is in my State, using H2O2 aka Peroxide.  They did the research four years ago. Their machine handles whole shipping containers of masks.

https://www.battelle.org/newsroom/news-details/battelle-cleared-to-sterilize-n95-masks-at-max-capacity-operate-in-other-states-to-fight-coronavirus-ppe-shortage.

Process is Vapor Phase Hydrogen Peroxide.

Steve

Caliaxy:

--- Quote from: Buriedcode on March 17, 2020, 09:51:36 pm ---I'm not sure I've seen it mentioned here, but 70% isopropyl alcohol (rubbing alcohol) is more effective at disinfection than 80%+.  Although I vaguely remember this being the case for bacteria, unsure about viruses.

--- End quote ---

A very plausible explanation I heard for that is that alcohol evaporates faster at higher concentrations. Even though 95% alcohol is more effective per se than 70% (in destroying bacteria and viruses), it stays on surfaces for a shorter time, thus its overall efficiency is reduced. 70% seems to be the sweet spot. Of course, this only applies to disinfecting surfaces, it doesn't applies to disinfecting objects immersed in alcohol.

pipe2null:
I have not been able to find COVID-19 specific engineering data, but some medical professionals have used data from SARS-CoV studies for sterilization guidelines.
https://www.eevblog.com/forum/projects/covid-19-related-engineering-data-ftlog-data-only-please!/msg2992562/#msg2992562

For SARS (similar to coronavirus):
Heating less than 75 degree C is NOT sufficient to kill all the viruses.
"...it was completely inactivated at 75 ◦C in 45 min (Fig. 2C). Surprisingly, at both 56 and 65 ◦C the virus was inactivated at early time points but at 60 min a small amount of virus was detected."

UVC (254nm) is effective at killing the virus much faster than heat, 6 - 15 min.
UVA (365nm) has no effect.
NOTE: If you are reading a study that has to do with UV, if they do not specify the wavelength used (nm), then you should greatly discount their UV related results...

As far as reusing masks go, profdc9 posted a collection of info:
https://www.eevblog.com/forum/projects/covid-19-related-engineering-data-ftlog-data-only-please!/msg2992912/#msg2992912


--- Quote from: Siwastaja on April 01, 2020, 12:53:52 pm ---...
I found quite different requirements for the energy of killing viruses on surfaces with UVC. One study suggested 9J/m^2 or 14 J/m^2 for killing 90%, or 98% of the viruses, respectively. The latter being 1.4 mJ/cm^2, those pesky 10-20mW UVC LEDs might be appropriate for disinfecting more than just toothbrushes. They are still quite expensive, though; one 10mW LED clearly isn't enough to disinfect large area of surfaces or large volumes of air. But I guess there is a lot of difference based on how much material there is for the light to penetrate; for masks, it's useless, as discussed, because the UVC light would need to penetrate many millimeters of the material. A lot of energy is needed for this, likely damaging the material. Heat works better.
...

--- End quote ---
If you found professional or academic studies on this, would you mind please posting them to the above-linked thread?

Siwastaja:

--- Quote from: pipe2null on April 01, 2020, 05:38:41 pm ---If you found professional or academic studies on this, would you mind please posting them to the above-linked thread?

--- End quote ---

I found a few by simple googling. Just made my own napkin memo & calculations, didn't save the references, sorry. You should be able to repeat the googling and find even more than I did, though.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod