There is supposed to be an indicator strip on the side of the cartridge which changes color when the cartridge should be replaced. At least thats the way mine are.
Bob Schramm
Check out my web page at:
http://www.SchrammStudio.com
also look at:
http://www.wlsc.wvnet.edu/www/pubrel/photo.html
>From: shannon stoney
>Reply-To: alt-photo-process-l@sask.usask.ca
>To: alt-photo-process-l@sask.usask.ca
>Subject: respirator cartridges
>Date: Fri, 29 Mar 2002 21:00:46 -0600
>
>Does anybody know how to test respirator cartridges to see if
>they're
>still good or not? The company I bought mine from couldn't give me
>any information on this matter. I think I read somewhere that you
>can check by seeing if you can smell some strong odor with it on,
>such as an essential oil or something. If you can't, does that mean
>it's still filtering, say, acid gases?
>
>--shannon
>--