Dear Mike,

Thanks for the information.

Do you know where I can get any information correlating conductance and PPM 
in order to use a TDS meter to determine concentration?  What is the 
approximate % error using the method?

James Osbourne, Holmes

[email protected]

-----Original Message-----
From:   M. G. Devour [SMTP:[email protected]]
Sent:   Monday, December 14, 1998 4:43 PM
To:     [email protected]
Subject:        RE: CS>More newbie questions!

James wrote:

> According to folks who have tried, a TDS meter---in reality a very
> low range meg-ohmmeter calibrated to read in micro-Siemens or TDS-is
> not usable to determine conc. of Ag sol.

The TDS meters from Hannah are indeed *conductance* meters. They
*are* usable to achieve consistancy from batch to batch, and as an
indirect measure of (approximate) concentration.

You simply have to ask: Is conductivity related to concentration of
CS particles in any reproduceable way? The answer is yes. It is
likely a very *complicated* relationship, however, so you cannot just
read the meter directly. But, you can probably create a calibration
curve that would work for a limited set of process conditions.

The real value is that, once calibrated to a salt or calcium
chloride standard, then any two of us can set up the same production
environment, process to a certain conductance reading, and be able
to expect we're in the same ballpark of useful ppm. (PROBABLY!)

If *I've* properly analysed my product, you can now have reason to
hope that *your* product is approximately the same.

Again, it isn't necessarily an *accurate* tool, but it's reasonably
precise and reproduceable, and therefore useful for certain things.

Be well,

Mike D.




[Mike Devour, Citizen, Patriot, Libertarian]
[[email protected]                       ]
[Speaking only for myself...              ]


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