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lemniscate

UV sanitizing lights

21 posts in this topic

Hello dcarch,
Thanks for sharing all the great info on the meal preps. I am duly impressed. I'm just starting fiddling with sous-vide and learning through egullet the tips and tricks of the practice. One thing you posted got me into a slight obsession. You stated you used a 55W UV light for sanitizing. I immediately did multiple google searches and came up with 55W bulbs, but could not find the fixtures for the bulbs. Can you tell me what you use? Was it a home-built or did you purchase a pre-made unit? It is now on my list for *need* instead of *want*. Any help/advice will be greatly appreciated.

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Hello dcarch,

Thanks for sharing all the great info on the meal preps. I am duly impressed. I'm just starting fiddling with sous-vide and learning through egullet the tips and tricks of the practice. One thing you posted got me into a slight obsession. You stated you used a 55W UV light for sanitizing. I immediately did multiple google searches and came up with 55W bulbs, but could not find the fixtures for the bulbs. Can you tell me what you use? Was it a home-built or did you purchase a pre-made unit? It is now on my list for *need* instead of *want*. Any help/advice will be greatly appreciated.

Very good question.

Germicidal UV light is very effective for sanitizing use in the medical industries. But you have to be careful in it's use.

1. Make sure there are no one in the room when it is on. I use an extension cord to plug in the light from another room sp that I don't have to be in the same room.

2. UV light can bleach color. If you have wood floor or wood cabinets, after a while you can bleach the wood color. Also, remove all artwork on the walls.

3. Have some ventilation because UV light can generate some ozone.

4. Read the label of UV bulbs for disposal because they may have mercury metal.

A 55 watt four pin UV light bulb will operate in a 55 watt four pin fluorescent fixture. Make sure the four pins are the same configuration. There are two kinds. Or you can get an adapter. Many fixtures have more than one tube in design. Just remove one and substitute with a UV bulb.

Light fixtures using High Output 55 watt bulbs for aquariums would be what you should be looking for.

dcarch

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I'm wondering about the efficacy of the UV to sanitize a room. My physics is distant, but I do recall that the energy of non-collimated light falls rapidly (I think logarithmically) as the source becomes more distant. How close does your light have to be to have any effect?

Edited to add-

The home marijuana growers have sorted this out. In this table the effect of distance on effectiveness is illustrated http://forum.grasscity.com/indoor-medical-marijuana-growing/209195-light-plant-distance-charts-how-far-should-light.html


Edited by gfweb (log)

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I'm wondering about the efficacy of the UV to sanitize a room. My physics is distant, but I do recall that the energy of non-collimated light falls rapidly (I think logarithmically) as the source becomes more distant. How close does your light have to be to have any effect?

Edited to add-

The home marijuana growers have sorted this out. In this table the effect of distance on effectiveness is illustrated http://forum.grasscity.com/indoor-medical-marijuana-growing/209195-light-plant-distance-charts-how-far-should-light.html

Your comment is correct for a point source in an open space.

In the case of this 55w bulb, it is a lineal source plus a focused reflector, the intensity of the light can reach quite a distance.

Even a point source if backed by a reflector can focus the light to reach long distance, such as a flashlight.

dcarch


Edited by dcarch (log)

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So how do you use it? I'm confused.

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So how do you use it? I'm confused.

Effectiveness of UV light is based on intensity and exposure time. The more intense and the longer you expose the area, the more germs killed.

I basically mount the light on a camera tripod and move it around the kitchen to avoid shadow areas and to improve intensity. I expose each area for about 10 minutes.

Besides germs, UV light can also kill micro insects such as dust mites.

dcarch

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interesting. this is True Madness in the Kitchen.

as interesting as this is, I doubt this adds to a 'healthy kitchen' in a medical sense in average urban settings.

ie LD50 for serious illness. I can see it might make a big difference in less hygienic settings.

Im not in anyway trying to put you off this True Madness.

Gloves / Bleach / Elbow grease

but I like the non-parallel thinking.

most hospital bacteriology labs have a zillion UV fluorescent lamps turned on at night when no one is

(supposed) to be there. they turn off when any of the entry doors open, automatically.

just saying.

however, id never eat anything that had been in those spaces for more than a nanosecond.


Edited by rotuts (log)
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Without knowing the irradiance of the bulb I can't figure out the appropriate distance for sterilization, but it probably has to be pretty close...inches, I'd bet, to work in any practical time period.

It sounds like a lot of effort!

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I don't see the UV effect the same as the lumens effect which is determined by your retina.



it might not take a lot of UV energy to kill various pathogens 'floating around'



if you ran a kitchen for the truly immunocompromised, I can see this as something to look into.



from the Madness thread.

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rotuts, hospital labs are staffed around the clock, at least they were when I worked in one.

I don't recall this method of sterilization being used in the lab, but that could just be because I didn't work in a reference lab.

"Don't eat in the lab" are words to live by.

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In my home I have a decently sized '1/2' greenhouse like structure attached to an area in the livingroom/dinningroom/familyroom area. its one large room after i took out a wall.

it was there when I bought the house in the low '80's I was thrilled. Id move in my soon to be large collection of herbs for the winter there and have fresh herbs all winter ( New England Winter )

never got it going well : bugs esp those white flies

but having experience in Bacti : I though UV fluorescents at night !

we then, there was the Cat or Two, the Dog or Two ...

I can tell you the bugs dont like rosemary. thats it.

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I'm still stuck on the dosing of UVC. I have a hard time finding actual protocols for surface sterilizing...there are plenty for decontaminating the air or water flowing past a UVC bulb.

If a UVA tanning booth is analogous (and it may not be for a number of reasons...different wavelength, different activity etc), the distance needed for effect is inches.

http://americanairandwater.com/port/mobile.htm is a portable thing marketed for room sterilizing. They give no times or room sizes or data for efficacy, but I note that the thing has a 24 hour timer on it.

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in many cases the labs were partitioned at least in the previous century.

the area that made all the media, w the auto claves etc had the lamps on at night.

about 1/2 of the staffing area where techs worked was closed off and had the lamps on at night.

the area staffed 24/7 was a bit smaller and had no lamps. but you had access to all areas for odd items and the lamps went out when you opened the doors and came back on when you closed them.

these areas 'ooozed' culture media it was in the air !

I could tell you about a few OR's in an Eastern City in 'Mecca' very very close to, if not in Boston MA

that had these lamps on during hip replacement surgery but as far as I can recall, no cooking was done.

I called it General Hospital. :biggrin:


Edited by rotuts (log)

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There are spray sanitizers which claim to be 99 % kill effectiveness on contact .

That may be true. However, the atomization only covers may be 50% of the area.

UV light covers 100% of the area, except in shadowed areas. UV light is totally non-toxic.

I use UV light mostly when I prepare food for guests who I don't know how healthy they are, and I use UV light sometimes when I dry-age beef or when I have to store food for a long time.

I got the idea of using UV light when I was visiting friends who work in the Rockefeller University research labs, where there are many germ free facilities. 55 watts is a lot of UV light.

dcarch


Edited by dcarch (log)

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interesting continues

my local market has dry aged beef. they have a large glass enclosed area where you can see the Beef

rot age. they must have some sort of glass that does not transmit UVC ( or UVX ) because they are on during the day.

unfortunately the beef is 'choice' quite expensive, and way not worth it. the Swells that are clueless dont seem to mind.

full prime is another mater.

I can tell you from personal experience: it might not matter at all w decent routine hygiene

immunocompromised is a different game.

those OR's w the lights? no different infection rate ( vary different issues here ) but if you are a Full Swell at the Mecca,

what's to do ?

they say this and its fairly true: Science Advances as Old Scientists 'Pass On'


Edited by rotuts (log)
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"------those OR's w the lights? no different infection rate ---"

Those labs in the Rockefeller U are research labs where extremely expensive experiments are conducted with extremely expensive germ-free animals.

dcarch

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good point

'germ free' is the key

after a certain point, its been shown that the OR infection rate in 'normal people'

( those that have been closer than a mile to a McDonalds in the last year )

:huh::blink::biggrin:

comes from internal bacteriology.

brush your teeth lately?

:blink:

humans as above are essentially cesspools compared to germ free.

those who work w germ-free I personally respect immensely

BTW under other medical circumstances:

hand washing, and a clean one use 'gown' ( not those grubby white coats )

changes the infection rate dramatically not only in the ER but the ICU

don't eat anything there either !

well maybe a Bon-Bon

Sooooo

back to the Pot on the Stove :

having ( chicken, beef etc etc etc ) ??

wash your hands. use a 'one way towel' esp w chicken


Edited by rotuts (log)
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Dental work always stirs up bacteria. Strep viridians and the like. One of my friends (a microbiologist) had a hip replaced a few years ago and she always has to take a course of antibiotics before having any dental work done.

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Dental work always stirs up bacteria. Strep viridians and the like. One of my friends (a microbiologist) had a hip replaced a few years ago and she always has to take a course of antibiotics before having any dental work done.

Its been well shown that no joint infections are prevented by using antibiotics like that. One of those things that makes sense but isn't true when it is investigated. The reason is that brushing teeth (and probably chewing as well) gives little pulses of bugs in the blood too.

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the issues above are related to laminar blood flow. If your New HIp has been around a while, and well healed, its very likely that dental work will not cause it harm

however, respect the medical situation you live in. that's what you have

Antibiotics are required pre dental work for congenital heart disease and certain 'murmurs' in the vascular system that suggest

'non laminar flow' why? that type of flow might damage the lining of the blood vessels so that a bit of that Toothy Brushing

might then end up

there and grow. because the natural lining was compromised.

Ive also known various Infectious Disease Folks smart folks for sure that would love for you not to ever brush your teeth !

maybe swish and swallow ?

football is pretty bad right now.

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Yeah , me too.

But when its studied its hard to show any benefit. In the end you have to trust the data if there's enough of it.

To bring this back on topic will be tough.

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