[at-l] Re: By the numbers

["W F Thorneloe, MD" <thornel@ibm.net>]

Actually, it doesn't. The way UV light works is to have deep penetration 
into the water shortly before entering potable water supply. Commercial UV 
does this by passing water through a bank of UV sources, allowing a slow 
flow and turbulence to assure that essentially all water touches the light 
source (as well as suspended nasties). Solar UV is not that efficient, at 
least in dark and wooded country like the Smokies. This might work above 
tree line in Rockies or Himalayas, where tickle out flow is spread across 
rock and exposed to direct sunlight for an extended time.

The portable UV will be a pump (slow) and light combination, with a 
prefilter. To do the job that will kill Giardia cysts, I suspect that 
weight benefit will belong to the current pump systems for a long time. For 
those who require viral free water, purifying systems (pump, filter, and 
iodine) will be required, but this is usually limited to third world 
travelers. For those most interested in weight savings, Iodine will remain 
the standard.

Got to go and get ready for my Rotary club, as we prepare to fend for our 
lives!

;-)

OrangeBug
Atlanta, GA

At 07:45 PM 7/29/1999 -0400, David  F. Addleton wrote:
>This may go a long way in clarifying the comparison between sunlight and
>the steripen.

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