Re: [at-l] UV TECHNOLOGY FOR WATER SUPPLY TREATMENT(http://www.trojanuv.com/papers/waters

["David F. Addleton" <dfa@wimlaw.com>]

I had to double check this one, because I thought it would be cubed, too.
But the uv technological literature uses the units I described below when
talking about the uv light involved. When you think about it, using the
time variable lets you get away, to some small extent, with the square
instead of the cube; and, we measure intensity of light in a plane, eg.,
the old light meters I used when measuring light for a particular exposure
on a roll of film. The cube deals with moving that light intensity
measuring plane backwards and forwards in relation to the light source.

But, and here I still have your problem regarding the square vs the cube:
there's got to be some variable in addition to time to define the volume of
water purified by a given unit of uv milliwatt seconds per centimeter
squared. I haven't yet found that, but I think you're right in your post to
Jim that moving the water near the uv source has something to do with
process. Also, we never drank from the Indus river, though if flowed for
many miles in sunlight -- it wasn't shallow enough of fast moving enough.
I'm still looking in to this issue, since you've questioned a very
long-held, allegedly scientifically based, belief, so I'll need some pretty
solid experimental observations and numbers to change it and to attribute
our anecdotal success with solar disinfetion to sheer luck and odds. 

> Are you sure? Shouldn't CC's (cubic centimeters) be the issue, not simply

> the surface area of the water?
> 
> At 04:47 PM 7/27/1999 -0400, David  F. Addleton wrote:
> >The unit of "power" for uv purification is defined in terms of milliwatt
> >seconds per centimeter squared
* From the Appalachian Trail Mailing List |  http://www.backcountry.net  *

==============================================================================