Danno said:
<nod>, I suspect that it would take quite a few LED modules to do the job,
maybe covering the entire inside of a tank's cap. My personal interest is of
a much smaller capacity, something along the lines of a litre or 1/2 litre
at a time, when I am hiking for instance. I would prefer to use LEDs because
they seem, in my experience, more robust.
As in "less subject to damage from physical shock/vibration, yes."
I am speculating that they would be
more energy efficient than tubes as well, but that it pure conjecture on my
part.
Perhaps...
Trouble is, UV LEDs are notoriously short-lived compared to their
visible and infrared outputting cousins. Typical advice I keep hearing
anytime I go looking at UV LEDs for whatever reason is to expect them to
be functional for less than a tenth of the usual lifespan of a visible
or IR LED.
That's problem 1.
Problem 2:
UV, blue, and white LEDs are serius power-suckers as far as watts per
light-unit of output. To feed them, you need more power than IR or
visible LEDs - Dont expect your batteries to last long...
Problem 3:
The wavelength. I'm certain that it's *POSSIBLE* to get LEDs that put
out the right kind of UV, but I doubt that any "off the shelf" units can
be had for a decent price, or without being special-ordered.
Problem 4: (Which ties into problems 1 and 2)
When your batteries and/or UV LEDs go dead, how do you propose to find
this fact out? UV is, by definition, invisible, so flipping the switch
is going to be one of those "I wonder if it's working?" things unless
you've got some way to verify (perhaps a UV-sensitive camera you can
point at it?), which in turn makes your "sterilizer" pretty much
useless, at least in my eyes - "I can't be *CERTAIN* it's functioning as
intended, so there's no way to know whether what's coming out of the tap
is safe to drink"
I suspect you'd be *MUCH* better off sticking with a UV tube and a power
supply to feed it - At least then you can be sure that you've got the
right kind of UV happening, and you've got a visual indication (UV tubes
aren't anywhere near as monochromatic as LEDs are, so there's always at
least SOME visual indication that tey're operating)
Oh... Some advice: *DO NOT STARE INTO UV SOURCE WITH YOUR REMAINING
EYE!*
Better yet... There's this spiffy new concept called "Iodine tablets"
that is intended specifically for purifying "survival"/hiking/etc water
water... I Keep hearing rave reviews about them being quite useful, and
requiring zero power input (unless you count the power you use in
scooping the water out of whatever source you find it in...)
If you ABSOLUTLEY MUST go the UV route, I'd suggest one of those
coleman/etc. lights that has the small flourescent tube in it - Just
replace the normal tube with a "barber's lamp" (remember when barbers
had a little toaster-oven looking thing filled with a queasy bluish
light that they'd park combs and scissors in between customers? The
bulbs for those...) to get raw UV instead of white light.