On Tue, 28 May 2002 13:48:51 -0700, "James Allison" <[email protected]> wrote:
>I'm just curious as to what you base your opinion about the meters on? >From >what I understand, they both read conductivity, and both do the same job, >except that the PWT reads in µS/cm instead of PPMs like the TDS1 does, which >actually makes the PWT harder to use, because you need to divide the number >from the PWT in half, in order to get an accurate reading. At least that's >what all the techs over at Hanna have told me time and time again. If you >have info that differs, please let me know. Yes, both meters test conductivity. It's the range and error limits of the meters that make the PWT useful and the TDS not useful. Both meters are accurate to (as I recall, don't feel like looking it up right now) 2% of full scale reading. The difference is that the full scale for the TDS is something like 500 uS, while full scale for the PWT is 100 uS. So, the TDS is accurate to within +- 10 uS (a 20 uS range) while the PWT is accurate to within +- 2 uS (a 4 uS range). IOW, a meter reading of 10 on the TDS could mean anything from 0 to 20 uS, while a meter reading of 10 on the PWT could mean anything from 8 to 12 uS. When used for making CS, trying to measure distilled water (which should read below 2 uS) and the CS you make (which should read around 10), the TDS error rate swamps the readings -- you can't rely on the readings to be anything meaningful. Physicists (and radio people) will say that the signal buried by the noise. -- Dean -- from (almost) Des Moines -- KB0ZDF -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: [email protected] -or- [email protected] with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: [email protected] Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <[email protected]>
