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UV lamp for sterilizers

A

artis sideley

Jan 1, 1970
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I intend to acquire an UV sterilizer for my aquarium water, I've found out that the market currently offers 2
technologies: UV Led and mercury vapor discharge. Mercury vapor is well known, but does the UV emitter LEds fit the job
and how long it could last ?
 
S

Steve

Jan 1, 1970
0
255 nm UV leds
http://www.s-et.com
http://shop.spectrecology.com/category.sc?categoryId=10&gclid=CL7m69K6wJUCFQopIgod3hBqRg
http://www.roithner-laser.com/LED_UV_SEOUL.htm
http://www.socled.com/en/product/prd/DeepUVLED.asp

The 255 nm version costs $300. Perhaps the 254 nm line from mercury
is used since that happens to be the wavelength where such a laimp has
a strong emission. Maybe other UV wavelengths would also work for
sterilization but those wavelengths haven't been used because a light
source with strong intensity at other wavelengths is not readily
available. Lifetime of the 255 nm UV led is only a few hundred hours
and their intensity degrades with time.

UV leds near 400 nm are available for a few dollars.
 
D

Don Klipstein

Jan 1, 1970
0
artis said:
I have no other reference than the website of the company:
https://sklep.aquael.pl/webapp/wcs/...storeId=10001&catalogId=10001&productId=17015

Which contains no technical refs about the UV diode.

I guess I must directly ask them.

Yes, do that. I was surprised that UVC LEDs existed. Had no idea, but
Steve's links actually prove their existence. If the sterilization device
emits close to 253.7, the choice is up to you, whether to choose mercury
or LEDs. I guess I'd prefer the device with the longer lifetime.
[snip]

I would go with mercury vapor. UVC and UVB LEDs put out a few
milliwatts or less and cost big bucks.

The most germicidal wavelengths are UVC, but a little longer than the
mercury line - maybe around 265-270 nm or so. 253.7 nm is close enough.
The most effective LEDs would be of longer UVC wavelengths. Keep in mind
that longer UVC wavelengths are easier for UVC LEDs to produce than
shorter UVC wavelengths.
But whatever UV LED is best will not be as good as mercury vapor, unless
it will be irradiating a very small area from a unit having a requirement
of small size.

- Don Klipstein ([email protected])
 
D

Don Klipstein

Jan 1, 1970
0
Don Klipstein wrote:
[snip]
I would go with mercury vapor. UVC and UVB LEDs put out a few
milliwatts or less and cost big bucks.

If anyone finds any ref on approximately how many mW the LEDs shoot out
@253.7nm, one can make a meaningful comparison. My PHILIPS catalog lists the TUV
6W germicidal as shooting out 85mW of energy @253.7nm.

The TUV 6W is a glow discharge tube however, and it's not as powerful as tubular
germicidals. The same catalog lists the 15W germicidal having an output of 3.5W
@253.7, and the 30W germicidal 9W @253.7nm.

The SYLVANIA catalog lists an output of 1.4W @253.7nm for the 8W germicidal.

It doesn't list a 4W germicidal, which I expect to be closer to what might
likely be used inside a compact aquarium water sterilizer, but assuming a
roughly linear drop on energy output as a function of Wattage, the output of a
4W germicidal should be close to roughly half that of the 8W, i.e., 0.7 - 0.8W
@253.7nm.

If one knew the exact output of those LEDs @253.7, one could make a balanced
choice, based on Don's idea. However one would also need to know how many the
device uses. Note that if ONE costs $300, a purifier with an array of 20 to
increase output, would cost some mucho bucks and would thus seem prohibitive.

On the other hand, if the device uses just one LED, then clearly the choice
would have to be mercury.
The most germicidal wavelengths are UVC, but a little longer than the
mercury line - maybe around 265-270 nm or so. 253.7 nm is close enough.
The most effective LEDs would be of longer UVC wavelengths. Keep in mind
that longer UVC wavelengths are easier for UVC LEDs to produce than
shorter UVC wavelengths.
But whatever UV LED is best will not be as good as mercury vapor, unless
it will be irradiating a very small area from a unit having a requirement
of small size.

half a milliwatt of 254 nm for $300:

http://leddev.wordpress.com/2007/11/29/
finally-germicidal-uv-leds-for-the-rest-of-us/

1.5 mW at 280 nm:

http://compoundsemiconductor.net/cws/article/news/26133

255 nm LEDs have pricing ranging from about $10.50 each for a million to
about $30 apiece for 50K pieces to about $270 each for 1-10 pieces.
280 nm ones range from about $7 each for a million to about $170 each
for 1-10 pieces.

The datasheet mentions a 280 nm one producing half a milliwatt.

http://www.s-et.com/?gclid=CKGo7vrShJYCFQQrFQodk21bEg

- Don Klipstein ([email protected])
 
J

Jeff Jonas

Jan 1, 1970
0
I intend to acquire an UV sterilizer for my aquarium water, I've found out
Are you sure these are UV LEDs?
Water sterilization as far as I know (Sylvania engineering catalog),
depends on the 253.7nm UVC mercury line to be effective,
because this line's emissions are
very close to the optimal bacteriocidal wavelength for moulds,
bacteria and many gram-positive micro-organisms, such as staph.
Are there LEDs that emit so low, in the vicinity of 253.7nm?

Google finds some:

http://ledmuseum.home.att.net/leduv.htm
ULTRAVIOLET 250-395nm Gallium Nitride

255 nm here:
http://www.roithner-laser.com/LED_diverse.htm
http://www.roithner-laser.com/LED_UV_SEOUL.htm

and:
http://www.photonsystems.com/sub/products/leds.php
Deep ultraviolet from an LED
230nm to 280nm
Photon Systems in developing a new family of deep UV
semiconductor light emitting devices.
LED devices between 250nm and 280nm are available now
and LEDs and lasers emitting between 230nm and 280nm are still in development.
Specifications
Model UV LED-280
CW output power: >0.5 mW
Center wavelength 280 ± 10 nm
Spectral linewidth <20nm FWHM
CW Drive current, forward: <25 mA, max.
Reverse current <100uA max.
Operating voltage, reverse: 6 VDC
Forward voltage 7.5V max.
Max.pulsed drive current: 200 mA at 1% duty cycle
Package TO-39 hermetic package with UV window
8.3mm dia by 4.5mm high

Model UV LED-255
CW output power: >0.1 mW
Center wavelength 255 ± 10 nm
Spectral linewidth <20nm FWHM
CW Drive current, forward: <25 mA, max.
Reverse current <100uA max.
Operating voltage, reverse: 6 VDC
Forward voltage 7.5V max.
Max.pulsed drive current: 200 mA at 1% duty cycle
Package TO-39 hermetic package with UV window
8.3mm dia by 4.5mm high
 
D

Don Klipstein

Jan 1, 1970
0
Google finds some:

<Examples, in short>

Notice the output powers - milliwatt and fractional milliwatt range.
Low pressure mercury germicidal lamps mostly produce watts of 253.7 nm UV.

- Don Klipstein ([email protected])
 
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