http://www.bghydro.com/mmbgh/Others/How%20do%20I%20calibrate%20my%20TDS%20meter.pdf
shows that the Hanna TDS meter is calibrated 2:1 between uS and TDS.
This is my understanding of the physics and why you have to double the
reading for ppm of ionic silver solution:.
1. TDS meters are set for sodium chloride. Sodium has an atomic weight
of 23 and chlorine has an atomic weight of 35.5. They both contribute
to the conductivity. Now ionic silver is Ag2O with an ion weight of 215
and 16. The silver thus has a mobility that is 23/215 or about 1/10 of
that of sodium, and the oxygen has a mobility that is about 2.2 times
that of the Chlorine. If you compute the total mobilities of the two
you would get 1/23 + 1/35.5 = 0.07 and 1/215 + 1/16 = 0.067. So at
first look it would appear that the calibrations are almost identical,
but you will note that the Silver ion carries a charge of 2, but the
Sodium only a charge of one. Thus the silver will have a mobility of
the electrons of twice that of the ions, and thus must be multiplied by
2 which give .134. When that is ratioed with the mobility of sodium
chloride you get a ratio of 1.91. If you add 5% colloidal component you
get 2.01 to one, which is very close to the 2:1 ratio given. If my
analysis is correct, then EIS with a colloidal component more than 5%
will actually be slightly higher ppm than using a TDS meter and multiply
by two or using the result of the conductivity meter. This is easily
seen by the drop off of the conductivity as the solution ages and some
of the ionic converts to colloid.
Marshall
j petras wrote:
Trem:
So you're differentiating the microsiemen meter (1:1) from the TDS
meter, which you say should be converted at half the value...do I
understand that correctly? They are functionally different?
The distinction in meters, if I am correct, is that the microsiemen
meter reads solution conductivity; and the tds reads just that -
dissolved solids.
Can you (or someone else) please send a link for reference, because in
my cursory research thus far, I have heard different things - thanks.
John
--- On *Wed, 9/8/10, Trem /<t...@silvergen.com>/* wrote:
From: Trem <t...@silvergen.com>
Subject: Re: CS>U/S to Silver Strength Reading
To: silver-list@eskimo.com
Date: Wednesday, September 8, 2010, 12:56 PM
It's 1 to 1 TDS readings are 1/2 the PPM
Trem
----- Original Message -----
From: "nessie" <nes...@shaw.ca </mc/compose?to=nes...@shaw.ca>>
To: <silver-list@eskimo.com </mc/compose?to=silver-l...@eskimo.com>>
Sent: Wednesday, September 08, 2010 9:33 AM
Subject: CS>U/S to Silver Strength Reading
> Hi Group:
> I think this has been discussed before. But I forget the
> outcome.
> Basically, what is the mathematical adjustment when
going
> from U/S (Microsemens) measurement
> to PPM for measuring silver strength/concentration .
Seems
> to me the silver strength/concentration in PPm was half of the
> microsemens reading?
> Is that correct or was it 2/3 the microsemen reading?
>
thanks...nessie
>
>
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