On Sat, 07 Jun 2003 10:58:34 +0200, Tony Moody <[email protected]> wrote:
>I guess that the 10ppm accuracy means the worst case expected at full scale >(2000ppm), after it leaves the factory. That works out to 0.5% accuracy at >fullscale, which is quite good for a cheap instrument. (imo Up to 2% >accuracy would be quite acceptable in the measured range. ) Assuming say 1% >accuracy and that the CS that you are trying to measure is about 10ppm, then >the reading could be out by about 0.1ppm. It would be good to have a look at >a calibration curve for the TDS-1 meter Umm, let's say the full scale reading is 1000 (for ease of accuracy calculations -- and I've heard some TDS meters have that range). If the meter has a .5% accuracy *of full scale,* then ANY reading on the meter is accurate to within +5 ppm and - 5 ppm of the reading. That is, if the ppm of the solution being measured is 20 ppm (ascertained with a lab-grade instrument), then the .5% accurate TDS will have a reading anywhere between 15 and 25. But I've heard the accuracy of the TDS is really 1% or 2% (I had one, but gave it away once I got the PWT). That means a reading of 20 would mean the solution is somewhere between 10 and 30 if it's 1% -- and between 0 and 40 if accuracy is 2%. -- Dean -- from (almost) Des Moines -- KB0ZDF -- 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: [email protected] Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <[email protected]>
