July 03, 2020, 06:47:08 AM
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Topic: Disinfecting masks in commercial environment  (Read 551 times)

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Offline pcm81

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Disinfecting masks in commercial environment
« on: April 06, 2020, 02:25:13 PM »
We now need to wear n95 masks at work. Management is trying to come up with a way to disinfect them. My initial thought was sodium percarbonate in water as oxygen source with masks hanging above the water all enclosed in a chamber to keep oxygen concentration in air high.

Would this be a good way to approach the problem? If so, what sodium percarbonate concentration should we target as a function of the volume of the chamber to yield oxygen concentration in the air high enough to disinfect?

1oz of sodium percarbonate yields about 1% h2o2 concentration in water, but I am having trouble extrapolating it to O2 concentration in air above the water pot.

Thanks ahead

Offline pcm81

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Re: Disinfecting masks in commercial environment
« Reply #1 on: April 06, 2020, 02:29:35 PM »
UV light is another method we're looking into. In this thread I am trying to gather information on oxygen via sodium percarbonate path to see if it is at all viable.

Offline wildfyr

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Re: Disinfecting masks in commercial environment
« Reply #2 on: April 06, 2020, 04:52:06 PM »
You need to aerosolize the aqueous solution.

Offline pcm81

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Re: Disinfecting masks in commercial environment
« Reply #3 on: April 06, 2020, 06:56:29 PM »
You need to aerosolize the aqueous solution.

Thanks. I guess I can do that with mist genergenerator and then dry the masks.

Offline Enthalpy

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Re: Disinfecting masks in commercial environment
« Reply #4 on: April 07, 2020, 05:21:53 AM »
I don't grasp the bizarre process of percarbonate in water but masks outside the water. My spontaneous thoughts (but I'm very bad on biology) would be:
  • Sterilize in an authentic autoclave. Maybe a cooking autoclave, with water - but only if no exiting vapour carries viruses.
  • Wash in a washing machine, with washing powder, preferably hot if the masks survive that.
  • Immerse the masks in the percarbonated water.

Percarbonate in water releases hydrogen peroxide. This isn't still oxygen in water: the peroxide must decompose first, and this reaction is hard to predict. So, no way to predict an oxygen concentration above the solution, but the probable outcome is: normal air. And I'm not sure at all that O2 destroys viruses. Peroxide is much more active.

If you achieved oxygen around the masks, for which an oxygen bottle is much simpler and predictable, it would be a BIG explosion risk, possibly with detonation. Organic fabrics burn well, in an enclosure: boom.

Offline AWK

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Re: Disinfecting masks in commercial environment
« Reply #5 on: April 07, 2020, 05:30:28 AM »
Ozone?
AWK

Offline wildfyr

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Re: Disinfecting masks in commercial environment
« Reply #6 on: April 07, 2020, 08:20:13 AM »
Ozone will damage the polymers in the masks.

You want aqueous peroxide in contact with the virus particles. Period. That's the goal. I like an aerosol for its gentleness and quick drying, but good old dunking should do it too.

I will point out though, that I bet you have no ability to tell if it works, or whether you've lowered the efficacy of the masks.

Offline Enthalpy

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Re: Disinfecting masks in commercial environment
« Reply #7 on: April 14, 2020, 05:25:04 PM »
[...] I bet you have no ability to tell if it works, or whether you've lowered the efficacy of the masks.

That's one advantage of the washing machine with washing powder. Their effects on clothes are well known. If the masks are designed for 90°C washing, a decent washing powder is supposed to destroy viruses. With other processes, one taps in the dark.

Offline pcm81

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Re: Disinfecting masks in commercial environment
« Reply #8 on: April 19, 2020, 08:26:49 PM »
Thanks all for the discussion and recommendations.
My manager took the easy way out and said that "everyone should maintain and clean their own mask"... I guess i should've expected something similar from a $70 billion dollar company... They didn't make all those billions by spending moneys.

Offline Enthalpy

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Re: Disinfecting masks in commercial environment
« Reply #9 on: April 23, 2020, 04:33:27 AM »
It's also a matter of liability, not only costs.

Offline Enthalpy

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Re: Disinfecting masks in commercial environment
« Reply #10 on: April 29, 2020, 07:13:47 AM »
After experiments, +70°C fails to destroy safely all Sars-Cov2, but +90°C over 90mn is being tested
https://www.n-tv.de/panorama/Empfohlene-Maskenaufbereitung-unwirksam-article21746637.html (in German)
Nothing difficult, BUT the masks must withstand this temperature. Cloth from used bed sheet for instance. Knots rather than rubber bands.

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