UV-C Light, does it affect/damage LED CoB chips with repeated exposure?

Ford

Sr Product Manager, Chauvet Professional
Joined
Oct 19, 2007
Location
South FL
There are definitely UV resistant plastics. We use them in some of our fixture lenses, and housings (specifically, units with IP6x ratings). The IP rating has nothing to do with UV resistance, but (to us, anyway) is an indicator of likely outdoor usage.

The need for quartz is to prevent UVC from generating Ozone. That is why UVC lamps from Osram and Philips have quartz envelopes.

In reference to other items inherent resistance to UV... my short answer is, if you wouldn't put it outside without expecting it to fade, It probably should't be exposed to daily, large doses of UV from any source.

In other words, don't use UVC to disinfect all of your stolen artwork. The old masters did not use UV resistant paint.

In our Video Panels, we have found that we need to use UV resistant LEDs to prevent damage from sunlight. If regular LEDs are used, you'll see color drift, intensity loss, and LED failure after regular (as in time period, not application) outdoor usage.
With fixtures which use lenses, the primary reason not to point them at the sun is not to protect them from UV energy, but to protect them from being burned like ants under Dave's kids magnifying glass.
 

Dionysus

Well-Known Member
Joined
Feb 9, 2009
Location
London, Ontario, Canada
Yes there are "UV resistant plastics" but I am very curious as how they behave with UV-C as only UV-A and UV-B get past the atmosphere from the sun and thus may not be a part of the testing protocol for plastics being tested to be used outdoors.

I think this is an important question requiring some research. Because I certainly don't know, does anyone else? Remember that the wavelengths of UV-C are not commonly present in nature (on the surface of earth) and that is exactly why they work so well for sanitizing. UV-A and UV-B also do kill things, but nowhere near to the same ability to do so.

I am trying to remember when installing UV in water treatment what the protocols were, we mainly used PVC conduit in such facilities due to chemical reasons and in some areas used explosion proof fittings and conduit.
 

TimMc

Well-Known Member
Premium Member
Joined
Feb 15, 2017
Yes there are "UV resistant plastics" but I am very curious as how they behave with UV-C as only UV-A and UV-B get past the atmosphere from the sun and thus may not be a part of the testing protocol for plastics being tested to be used outdoors.

I think this is an important question requiring some research. Because I certainly don't know, does anyone else? Remember that the wavelengths of UV-C are not commonly present in nature (on the surface of earth) and that is exactly why they work so well for sanitizing. UV-A and UV-B also do kill things, but nowhere near to the same ability to do so.

I am trying to remember when installing UV in water treatment what the protocols were, we mainly used PVC conduit in such facilities due to chemical reasons and in some areas used explosion proof fittings and conduit.
This is why I put the onus on the *manufacturer of the item to be cleaned/sanitized* to inform users of what materials, chemicals (and concentrations thereof), and methods can be used on their products without damaging the product. These are uncharted waters particularly in regard to UV-C, as most manufacturers never anticipated its use on their goods.

And again I will point out that something can be gross looking and unclean and still be "sanitized". That something does not look "clean" will cause most persons to think the object has not been sanitized. I will further point out that "sanitiziation" may not be practical for a number of objects, spaces, and places. Not trying to put the skids under any of the theatrical lighting folks who also make UV-C equipment, but while the efficacy of UV-C is known in certain types of spaces, there is very little known about using it to sanitize large public spaces that have lots of "shadow" areas (like auditoriums, stages and sets/scenery). I will further go out on a limb and say that for the most part, surfaces are not significant contamination vectors (that I've found so far, anyway) and cleaning/sanitizing high touch surfaces (hand rails, elevator buttons, counter tops) *while in use* is the most effective way to provide *genuine* cleaning. It does no good to zap a venue with UV-C after the public leaves and then surfaces are touched by 3000 ppl the next day before zapping occurs again. Only the first few persons benefit from the UV-C sanitation and the public will increasingly contaminate the surfaces for the duration of attendance.

I continue to advocate for *personal hygiene* and use of PPE as being more effective for workers. Doing a dog & pony show for the public is an entirely different matter. Worry about what's in the air from the people around you, not what is on a seat back (unless you have a habit of licking theater furnishings).
 

macsound

Well-Known Member
Joined
Jun 15, 2018
Location
San Francisco, CA
Still off topic here, talking about air conditioning, but I found this article about an early outbreak in China, exacerbated by the flow of air from the air conditioning passing from the infected person, spreading to people directly downwind.
I'm assuming this is a window unit, but could also just be a small restaurant with minimal supply vents.
"We conclude that in this outbreak, droplet transmission was prompted by air-conditioned ventilation. The key factor for infection was the direction of the airflow."
 

TimMc

Well-Known Member
Premium Member
Joined
Feb 15, 2017
Still off topic here, talking about air conditioning, but I found this article about an early outbreak in China, exacerbated by the flow of air from the air conditioning passing from the infected person, spreading to people directly downwind.
I'm assuming this is a window unit, but could also just be a small restaurant with minimal supply vents.
"We conclude that in this outbreak, droplet transmission was prompted by air-conditioned ventilation. The key factor for infection was the direction of the airflow."
Not a window unit, but the air return was in the dining area above a table (where a couple guests were infected). The air exit was a few feet above the return, IIRC.
 

jtweigandt

Well-Known Member
Joined
Aug 2, 2013
Location
Moline Il
jtweigandt, would you please share what UVC troffers you are using? Thank you.
They were sold to me by a company called Medical Illumination. Long time quality company in the human and veterinary medical exam/surgery light field.
I gab with them when I see them at a convention.. one of the guys at least had a Theater lighting background.. go figure..
http://www.medillum.com/products/uv24/ The unit itself is called Vidashield. no specific Covid trials, but some really impressive work on antibacterial effectiveness in hospital settings.
Anyway this is not a fly by night back of the truck operation... The unit itself has a tube style UV source, in a highly reflective chamber to maximize. Supposed to turn over a 10x10 room 4x an hour.
 
Last edited:

mbrown3039

Well-Known Member
Joined
Mar 20, 2018
Location
vegas, baby..!
I heard from another manufacturer today - and have heard from others since the original post - and the official answer seems to be.............."it depends."

Basically, there is no question that UV-C light will have a degrading effect on all plastics/acrylics. However, how damaging it is will depend on:

1. The specific formulation of the plastic in question;
2. The wavelength of the UV-C light;
3. The intensity of the UV-C light;
4. The proximity of the light source; and
5. The duration of the exposure.

Short of testing the exact fixture you're using with the exact UV-C light source you're using (or planning to), there is no way of definitively knowing the impact. m
 

mbrown3039

Well-Known Member
Joined
Mar 20, 2018
Location
vegas, baby..!
Why are we sanitizing things that by and large go mostly untouched?
@sk8rsdad is mistaken (about this subject, not TSA) - the original post has to do with the use of large-scale UV-C "bombers" (carts or stands) that you use by placing on stage, turning on a timer and walking away - which, if effective and without major side effects - would be a super convenient, low-labor way of disinfecting a large area easily. However, the question was posed (I summarize) "with all that UV-C, what happens to the plastics?"

So, it's not about disinfecitng a fixture that only gets touched 2-3 times a year, but what are the incidental effects of large-scale UV-C irradiation.
 

sk8rsdad

Well-Known Member
Premium Member
Fight Leukemia
Joined
Aug 15, 2008
Location
Ottawa
@mbrown3039 where did I say anything about disinfecting fixtures? I responded to the question about why there's this desire to sanitize surfaces that don't need or benefit from being sanitized.
 

TimMc

Well-Known Member
Premium Member
Joined
Feb 15, 2017
@sk8rsdad is mistaken (about this subject, not TSA) - the original post has to do with the use of large-scale UV-C "bombers" (carts or stands) that you use by placing on stage, turning on a timer and walking away - which, if effective and without major side effects - would be a super convenient, low-labor way of disinfecting a large area easily. However, the question was posed (I summarize) "with all that UV-C, what happens to the plastics?"

So, it's not about disinfecitng a fixture that only gets touched 2-3 times a year, but what are the incidental effects of large-scale UV-C irradiation.
Yeah, I know about the gear and the reason... I'm saying there is almost zero benefit and the costs associated with UVC disinfection of the stage, curtains, set, and lights/sound/video is unlikely to prevent infections of talent, crew, venue staff or public.. The money spent on either equipment or service company is most for "feel good" when the focus should be on proven infection vectors: air, breathing, proximity to same. To benefit performers, crew, orchestra, etc it means masks, gloves, and cleaning common (shared) high touch items where the users are incapable or unwilling to wash their hands or use a sanitizer after handling the items. It helps if the cast and musicians don't lick the furnishings or each other (previous comment in another thread about dipping the talent in whiskey).

I've spent the last 5 months working on coronavirus health and safety in theater, concerts, and sporting events. In musical theatre the biggest challenge is infection status of personnel and talent, proximity of performers to each other and crew (especially wardrobe/hair/makeup), sharing of confined spaces like dressing rooms, office spaces and while waiting in wings for entrances. None of this has anything to do with fomite (surface-based) transmission and resulting infection because.... wait for it.... with good hand hygiene, there is very little chance of transferring enough active virus to a mucous membrane.

"We" (a societal "we") have made surface cleaning/sanitation a far bigger deal that it needs to be if we're really wanting to minimize the risks to ourselves, the talent, crew, and venue staff. EVERY aspect of putting on a show, every department, each part of venue operations... will need do do their own evaluation as to where they get the greatest safety return for their efforts. Each will, as @sk8rsdad points out (and I've mentioned before) require some 'sanitation theater', but I submit that irradiating stages and bulk gear is all sanitation theater. For venues, UVC in the air handling system is good; trying to irradiate the auditorium and actually disable the SARS-CoV-2 virus? Eh, dosimeter cards are about $4 each and you'd need dozens EACH TIME, to show that seats, arm rests, hand rails, and the stage etc received sufficient radiation, mostly to make people feel good. I'd rather see a building services person with disinfectant and microfiber cloth wiping down handrails, door knobs/handles, and other things the public touches.
 
Last edited: