(Coronavirus) On UV Sanitization

[linux-works]

same idea holds; make rectangle wood frames, make a grid of crossing nylon lines and since they are thin, their effect of blocking is minimal. not sure if you want 100.00000% or if 99% if good enough; I plan to use a grid of nylon 'string', or at least try it. seems like its a cheap way to get this kind of shelf done, with mostly air being there and just tiny thin nylon lines for support. not for super heavy things, though.

(think: tennis racket and you'd be close)

 

[deonb]

same idea holds; make rectangle wood frames, make a grid of crossing nylon lines and since they are thin, their effect of blocking is minimal. not sure if you want 100.00000% or if 99% if good enough; I plan to use a grid of nylon 'string', or at least try it. seems like its a cheap way to get this kind of shelf done, with mostly air being there and just tiny thin nylon lines for support. not for super heavy things, though.

(think: tennis racket and you'd be close)

Difficulty: Super heavy things

Well, 25 lbs capacity is probably fine. I'm now looking at Quartz Rods, so just put in a bunch of side-by-side rods:
Fused Quartz Rods – Quartz Tube, Quartz Tubing, Quartz Tubes

Maybe 5mm thick per rod, and have one every inch.

Now how to prove UV transparency on those... order some and experiment I guess.

 

[linux-works]

you can build a meter. I'm putting together a design for one; not that there's all that much in the design.

then just compare the meter with air vs the meter with quartz.

the uva sensors on amazon are wide enough bw to 'see' uvc just fine. attenuated, but who cares. its a relative measurement you are doing.

arduino, sensor, display: $20 or less

 

[linux-works]

Difficulty: Super heavy things

I still like the rotating motor platform idea. the item on there (or items) will get hit by all angles. then you do flip the items again for the bottom side, but at least it rotates and gets coverage.

I'm also going to be allowing for a hanging slow rotation motor and a hook or alligator clip. that's where light things could be suspended and rotated and have almost no 'achilles' spots.

a regular old cookie sheet cooling rack thing is strong wire and has enough room between squares so it won't block that much light.

with ozone inside, I don't know if the light has to hit 100% of all surfaces.

 

[joetomasone]

How do you calculate mJ/cm2 from mW/cm2? Just multiply by number of seconds?

Yes. 1 joule = 1 watt per second.

 

[joetomasone]

Difficulty: Super heavy things

Well, 25 lbs capacity is probably fine. I'm now looking at Quartz Rods, so just put in a bunch of side-by-side rods:
Fused Quartz Rods – Quartz Tube, Quartz Tubing, Quartz Tubes

Maybe 5mm thick per rod, and have one every inch.

Now how to prove UV transparency on those... order some and experiment I guess.

Fishing line would eventually be deteriorated by the UVC - in theory. It will tend to degrade plastics over time.

I like this quartz rod idea. I may order some and retrofit Little Box as a test.

 

[deonb]

you can build a meter. I'm putting together a design for one; not that there's all that much in the design. then just compare the meter with air vs the meter with quartz.

the uva sensors on amazon are wide enough bw to 'see' uvc just fine. attenuated, but who cares. its a relative measurement you are doing.

arduino, sensor, display: $20 or less

I have a Lutron 254nm meter (https://inspectusa.com/uvc-254nm-ultra-violet-light-meter-uvc-254sd-data-logging-p-1592.html). It works well. Once I have a permanent room set up, I'll flood it with a bunch of Arduino-based sensors, but for now I can use the Lutron for experiments.

Fishing line would eventually be deteriorated by the UVC - in theory. It will tend to degrade plastics over time.

I like this quartz rod idea. I may order some and retrofit Little Box as a test.

I've ordered a few 5mm's and 10'mm. Should be here in a week to 10 days. I will stack them up as tight as I can and measure UV transmission through them using the Lutron, and will post the results back here.

 

[linux-works]

I'm assuming the whole inside will need to be checked and replaced, over time. and so, its all disposable. even the wiring is probably going to have plastic crack and the insulation get to be unsafe.

so I'm assuming it will need maint. over time due to the ozone and strong uvc. I mean, we're intentionally blasting high power in there, of course even uva/b rated outdoor plastic is going to get degraded by this intensity.

 

[deonb]

Are these statements on Far-UV accurate, and if so why aren't all subways, airplanes and airports drenched in them?

Effective UV Disinfection Lights: 4 Benefits of Far UV-C

 

[joetomasone]

Are these statements on Far-UV accurate, and if so why aren't all subways, airplanes and airports drenched in them?

Effective UV Disinfection Lights: 4 Benefits of Far UV-C

I've seen the "safer for humans" data posted enough to believe it, but that's the first time I've seen it posited that it's that much more efficient. It's just now really emerging as a disinfectant, and my understanding is that it's still very expensive. Assuming all the claims bear out, I'd expect to see widespread adoption sooner rather than later.

In doing some quick reading, it does indeed seem to be about 10x more efficient than 254nm UVC.

On price: "According to Brenner, 222-nanometer lamps sell for $500 to $800. Their production is being stepped up as we speak as local authorities and companies are driving exponential growth in demand."

 

[eevee-fan]

Are these statements on Far-UV accurate, and if so why aren't all subways, airplanes and airports drenched in them?

Effective UV Disinfection Lights: 4 Benefits of Far UV-C

Because it is very new... previously, it was all about UV-C in air handlers and mobile UV-C robots to do a final clean of Operating Rooms... I can see we switch to Far UV-C next to existing lighting and it just being on to kill viruses and bacteria continuously. Of course, whether it is harmless to humans, has to proven from long term use. On the Corona thread, one of the docs was laughing at the idea saying something like "beyond UV-C would be soft x-ray". But, as with all radiation, it comes down to strength and distance to determine whether something is safe or not.

 

[linux-works]

those boxes arrived (I linked to them on amazon). they are a decent price, you get two, and they are pretty large! bottom is reasonably flat, too (minor sculpting to add strength).

I was hesitant to cut holes in my other good boxes but these are cheap enough that I can finally get to work

they just barely fit in the m3 trunk, btw. I may bring a finished box into work, some day (...) and I need to know it can fit in my car. these fit, but just just barely (height wise)

 

[linux-works]

here's something I've been thinking about; wondering if anyone sees value in this part of the design.

idea is to have a small fan (pc 'case fan' style) that is controllable via the outside (I'm planning on a console that sits outside the box and controls/times various things inside) - and also have a way to keep it covered so that the ozone smell stays inside the box.

thinking about doing the uv light zap with the cover on, bringing the box out to a garage or balcony, then venting it outdoors. a fan would perhaps be nice, but even just opening the box while its not indoors will do the trick.

ideally, I don't want to be around while it purges the o3 from the box, so the fan would be a simple 12v fan and there would be a small li-po battery inside that will run the fan for a few minutes. it will be on the same remote control system (wifi web browser based, likely) so I can put the box outside, close the house door, trigger the box to start the fan and just let it run for a while to purge the ozone.

its a luxury feature, to be sure (grin) but curious if anyone sees value in this. I'm trying to create a system and pcb that will be full of options (hw and sw 'jumpers') so that builders can pick the things they want to include in their box build.

 

[joetomasone]

ideally, I don't want to be around while it purges the o3 from the box, so the fan would be a simple 12v fan and there would be a small li-po battery inside that will run the fan for a few minutes. it will be on the same remote control system (wifi web browser based, likely) so I can put the box outside, close the house door, trigger the box to start the fan and just let it run for a while to purge the ozone.

Unless you are sensitive to the ozone, simply opening it outside isn't going to do anything to you. You could even open the lid and come back in 10 minutes to remove the disinfected contents if needed. The ozone will also be disinfecting things, so it's a good thing to keep trapped in there during the process, especially if you are disinfecting anything with layers (like masks) as it will permeate where the UV light won't penetrate.

 

[eevee-fan]

New York transit agency launches UV light pilot program in effort to kill Covid-19 - CNN

 

[linux-works]

get ready for a lot of 'burnt hair smell' all over the place, though.

ventillation is not always a first priority, for many buildings; and for subways, I'm not sure they see much fresh air at all.

 

[eevee-fan]

get ready for a lot of 'burnt hair smell' all over the place, though.

ventillation is not always a first priority, for many buildings; and for subways, I'm not sure they see much fresh air at all.

Subway tunnels actually have active fans moving air out (and outside air comes in from the streets). Depending on the specific light, it may or may not generate ozone. I don't think ozone would be popular as it is a pollutant (smog).

 

[eevee-fan]

Hm... this looks dangerous if occupied.

 

[Big Earl]

get ready for a lot of 'burnt hair smell' all over the place, though.

ventillation is not always a first priority, for many buildings; and for subways, I'm not sure they see much fresh air at all.

New commercial buildings are required to have sufficient fresh air ventilation to control CO2. I operate several medium sized performance venues across two college campuses and all of the air handlers are capable of supplying up to 100% outside air (and exhausting 100% of the return air).

Unfortunately, there are plenty of non-compliant buildings out there. I know of one particular call center that has ~100 people working in a cube farm in a renovated warehouse. From what I can tell, none of their four air handlers has an outside air supply, so their workers are working in stale, recirculated air. This is a good example of a super-spreader environment.

I would like to see CDC or ASHRAE recommend increased fresh air ventilation in this post-pandemic world. I think that, in addition to generous UVC, could be very helpful in limiting the spread of the virus, particularly in high density venues like classrooms, offices, restaurants, theaters and concert halls. The trade-off is a significant increase in energy consumption on hot, cold and/or humid days, since you’re essentially climate controlling the outside. Cost and ignorance are the primary reasons why many building operators run the minimum amount of outside air required, and all-too-often, not even that.

 

[deonb]

Ok! After a month and some very intensive testing, I'm ready to report back on the results of using Quartz rods for shelves.

PLEASE don't take these values as-is and bet your life on them. Use them to decide what to order, and then do your own tests on your own equipment.

My test method. I've 3D printed a bracket to hold both the test instrument and then a rod right next to it. So you place the little jig on top of the sensor, and then slide a rod through the top. The rod will effectively lie on top of the sensor, and the jig blocks any additional light.

I've put the light direct on top of it and did tests, as well as removed the light by 18" and then test.

Here are the results. I've tested with both a 10mm quartz rod and a 6.35mm glass rod. It is obvious that the glass rod in the same test jig blocks close to all UVC light, which should validate that the test jig is valid, and doesn't let in additional UVC lights through another path.

At the same time the quartz rod goes from either blocking very little UV light than allowing MORE light through than a direct beam (probably performing some focus due to the curveture).

Based on this, I'd say this would make for a good base. The rods are pretty fragile, but I think they'd hold up with about 1.5" spacing between them. You'd have to place items carefully and not just drop it on there.

OpenSCAD source code for 3D printed test jig. You can just paste this into OpenSCAD, got to Design/Render, and then export as an STL.

difference()
{
cube([50, 50, 30], center = true);

translate([0,0,-5.2])
rotate([90, 0, 0])
cylinder(h = 52, r1 = 5.2, r2 = 5.2, center = true);

translate([-18,0,-8])
rotate([90, 0, 0])
cylinder(h = 52, r1 = 3, r2 = 3, center = true);

translate([18,0,-8])
rotate([90, 0, 0])
cylinder(h = 52, r1 = 3, r2 = 3, center = true);


translate([0,0,15])
rotate([90, 0, 0])
cylinder(h = 52, r1 = 5, r2 = 5, center = true);


translate([0,0,10])
rotate([0, 0, 0])
cylinder(h = 20, r1 = 20, r2 = 20, center = true);

translate([0,0,-2.2])
rotate([0, 0, 90])
cube([52, 11, 5], center = true);

translate([0,0,0])
rotate([0, 0, 0])
cylinder(h = 35, r1 = 3.3, r2 = 3.3, center = true);
}