Gaston, The TDS1 interprets the raw conductivity reading (uS), as that which would be obtained if the solution under test contained calcium carbonate (CaCO3), I am led to believe. It displays a modified output to reflect that fact, also converting the output to read CaCO3 as ppm. Other TDS meters use different standards.
The conversion factor to convert uS to ppm (as CaCO3) is 0.5 , ie. 2 uS per ppm, as you note. If you have not already purchased such a unit, can I suggest you buy a conductivity meter such as the PWT, which not only reads out in uS, but also has a greater sensitivity. The TDS1 has a sensitivity of +- 2ppm (4uS) vs +-0.2uS. I think that what I remember being posted. Obtain the calibrating solution from the meter supplier. Cheers Ivan ----- Original Message ----- From: "G. Boucher" <[email protected]> To: <[email protected]> Sent: Thursday, 13 April 2000 23:58 Subject: Re: CS>Hanna meter > Hi Ivan, Robert and other list members: > > FYI, I have also obtained a TDS-1 unit. > My unit, according to the supplier, has been > calibrated to read PPM. The unit has been > calibrated before being shipped to me with > a solution of 2 uS to read 1 PPM on the unit. > (This appears to match your comments Ivan) > > Naturally the unit reads in uS, but the readout > is in PPM. > > I have compared the reading with a conductivity > test (home made gadget) and the reading appears > to be very close. > > Therefore, it is most important before purchasing > one of these units to know: > > 1.- What the unit provides as a reading (i.e.: ppm or uS) > > 2.- What is the accuracy of the unit. > > 3.- Where to obtain the solution to calibrate the unit. > > This is my opinion on my unit. I cannot comments on > other units. > > Gaston -- 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]>
