UVC Tubes used in SteriPEN, Camelbak All Clear, etc.

[formatc]

I'm looking to build a low-power water purification device using UVC light. Some of the most common products currently available are the SteriPEN, Camelbak All Clear, and UV AquaStar. Although I was looking to accomplish this with LEDs, other forum posts here have indicated the diodes that produce the desired wavelength (around 265 nm) are not at all cost effective.

The other products use small fluorescent tubes which produce the correct wavelength as well as visible blue light. Are these small lamps available on the market (ebay or from suppliers)? My searches have only revealed larger lamps which are designed for air purification.

Thanks in advance!

 

[Optical Inferno]

Try Heraeus TUV 6WE. Don't know what it costs or too much about the company, but it may get you started.

 

[TEEJ]

Part of your issue will be enough energy to break bonds...not just the frequency. The light has to have the juice to penetrate through the water, and whatever turbulance is in it, etc. The larger the container/length through the water the light must penetrate, and the dirtier the water, the more power you need.

Otherwise, as the same frequencies are coming from the sun...all you'd need to do is hold a glass of water up to sunlight and it would be purified, etc....which doesn't work.

 

[mattheww50]

Part of your issue will be enough energy to break bonds...not just the frequency. The light has to have the juice to penetrate through the water, and whatever turbulance is in it, etc. The larger the container/length through the water the light must penetrate, and the dirtier the water, the more power you need.

Otherwise, as the same frequencies are coming from the sun...all you'd need to do is hold a glass of water up to sunlight and it would be purified, etc....which doesn't work.

Frequency (1/wavelength) is directly proportional to energy. There are actually two needs. One is that the photons produced from the source need to be sufficient energy to break chemical bonds,
and the seond issue is that you need a certain minimum energy per unit area to break the bonds in a reasonably short period of time. I suspect it is hard to produce a UV LED that produces enough UV energy in the right band to effectively sterlize in a short period of time. These devices tend to be very very low efficiency. By contrast you can get up to about 30% efficiency out of a mercury vapor UV source.

Sunlight can in fact disinfect, the problem is that due to atmospheric filtering very little UV of sufficient energy makes it to the gound, so disinfections takes many hours of direct sunlight exposure to delivery enough energy.

 

[AnAppleSnail]

Otherwise, as the same frequencies are coming from the sun...all you'd need to do is hold a glass of water up to sunlight and it would be purified, etc....which doesn't work.

Sure it does! However, note the varying attenuation of water of varying UV-A/B/C light, and issues with regrowth after being taken inside.

 

[DIWdiver]

If you are sterilizing water, it's probably for drinking, and won't have much turbidity. I wouldn't want to drink dirty water even if it was sterile!

Depending on the source, you might need a carbon filter to remove chemical polutants too.

 

[jspeybro]

cheapest sollution are low pressure germicidal tubes with old school ballasts.
there are ozon-generating and ozon-free tubes (not sure which one you need). Mind you that ozon is dangerous as it binds easier than oxygen to the read blood cells.

 

[cbsmith111]

I know this is old, but I've been wondering about it myself. The products like steripen aren't designed for "dirty" water. The concept isn't the same as some of the advanced filtration systems which will allow you to drink anything up to raw sewage. When you are backpacking in the wilderness there are usually sources of "clean" water that has already been filtered of sediment and dirt naturally but could still contain harmful organisms. I have no idea how they work but given the size and power level needed for the steripen (there's even a hand crank model" I had always assumed they used leds. They are also not incredibly expensive. I suspect there is a way to make something similar relatively cheap.

 

[LEDPunisher]

How about just straight generating ozone with an air ionizer and pumping it through the water with an air pump? Nothing like some good free radical action to wipe out organic matter!