-----Original Message-----

I don't know what an average lifespan might be; I would think it depends
upon the wattage of the tube it is filtering.  My understanding as to why
the filters expire is that they become saturated, i.e., the filters absorb
the UV rays and they can only hold so much.

____________

Actually when this happens you can take the sleeves down and rinse them out
over a pail and re-use them. It cleans all the old UV rays out of them and
makes them good as new. There's even a drop-off bin at one of the medical
clinics in town where they recycle the old UV rays and use them to treat
Seasonally Affective Disorder during the winter so the whole thing is
completely environmentally friendly.

Jeff "Friday comes early at the Archives" O'Brien


____________________________________

J. Jeffrey O'Brien
City of Saskatoon Archivist
Tel:  306-975-7811
Fax: 306-975-2612

2002 Calendars on sale now!  For ordering information and to see a preview,
visit us at:

http://www.city.saskatoon.sk.ca/org/clerks_office/archives/ar-gall.asp#2002c
alendars

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