I meant to add that neither meter will measure true colloids, as they are both not dissolved and do not carry a charge, other than that of the ions that are adsorbed to the colloid surface. Conductivity meters measure ions only.
Ivan. > -----Original Message----- > From: Ivan Anderson [mailto:i...@win.co.nz] > Sent: Saturday, 26 October 2002 3:05 p.m. > To: silver-list@eskimo.com > Subject: RE: CS>TDS/PWT meters > > > Paul has led you astray a bit in his answer :-) > > Both the TDS (total dissolved solids) meter and the PWT (pure water > tester) are conductivity meters. The difference is in the scale and > calibration. A TDS meter is calibrated to convert the conductivity > reading (micro-Siemens uS) to reflect the amount of > dissolved calcium > carbonate (in most cases) that would give rise to the conductivity > measured. This calibration is about 1ppm TDS to 2uS for CaCO3. That > would be fine if one could just multiply the ppm TDS x 2 to get the > equivalent conductivity reading in uS, however, most TDS > meters have a > scale 000 - 999 ppm TDS, and generally have a error of 2% > of the full > scale reading. The error is therefore +/- 20ppm TDS or a range of > 80uS, obviously too high if one is measuring a 10ppm CS > solution which > will have a conductivity reading of about 8uS. > > The PWT scale is much more suitable, being 00.0 - 99.0 and > the readout > is in uS. The error is +/- 2uS or a range of 4uS. > > Regards > Ivan. > > -----Original Message----- > From: kaselo...@aol.com [mailto:kaselo...@aol.com] > Sent: Saturday, 26 October 2002 1:52 p.m. > To: silver-list@eskimo.com > Subject: CS>TDS/PWT meters > > > please explain to me as simply as posible the difference between the > tds meter and the pwt meter when testing CS... we have two > tds meters, > and they both give totally different readings... if i understand > correctly, i need to invest in a pwt meter but i'm not totally > understanding why it is better... thanks! -- The silver-list is a moderated forum for discussion of colloidal silver. Instructions for unsubscribing may be found at: http://silverlist.org To post, address your message to: silver-list@eskimo.com Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <mdev...@eskimo.com>
