Hi Steve Foss.
Regarding your statement: (9th paragraph down)
"Sodium Chloride or table salt has twice the conductivity of Silver.
Or Silver has 1/2 the conductivity of table Salt. So any measurement
of Colloidal Silver will be half of that for dissolved solids."
Are you saying that salt is more conductive than silver? I don't
understand. Please elaborate.
Thanks,
Andy
In a message dated 8/16/2008 9:14:38 A.M. Pacific Daylight Time,
[email protected] writes:
Hi Silver List,
"What multiplier do you use and how accurate do
you think your measurements are???"
I use 4 as the multiplier with TDS meters. Why?
To date no major reputable commerical manufacturer produces
a meter to specifically test for PPM levels for Colloidal Silver
Suppensions. When I asked (Hannah), "Not enough sales to justify
manufacture, to small a market."
A TDS meter is designed to measure Total Dissolved Solids in
soltion for applications such as hydroponic gardening, testing tap
water and Reverse Osmosis water, industrial uses for contaminants.
The typical TDS meter measures from 0 ppm to 999 PPM and was not
designed to measure small measurements with an accuracy of less
than 50% under 100 of PPM
TDS meters measure transconductance (opposite of resistance) in
micro Siemens and then use circuitry to convert this measurement
into a PPM number (called a Conversion Factor).
The Conversion Factor circuitry "translates" roughly 1 micro
Siemen into 1ppm at Part Per Million readings of 100 PPM or higher
at 90% accuracy. At PPM levels lower than 100 PPM the Conversion
Factor translates 1 micro Siemen as 0.5 PPM, 50% of what is measured.
TDS meters were designed to measure dissolved solids conductivity
and are calibrated with Sodium Chloride (the "yellow" solution
sold with these meters) as a rough "Guesstimate." Salt is used as
an average approximation of the conductivity of the compounds and
elements (and polutants) found in water. (Potassium Chloride is
the world standard for calibration, but then TDS meters do not
require scientific accuracy.)
Soldium Chloride or table salt has twice the conductivity
of Silver. Or Silver has 1/2 the conductivity of table Salt. So
any measurement of Colloidal Silver will be half of that for
dissolved solids.
TDS meters round off their measurements downwards after
conversion. 0 to 0.9 PPM will read as 000 PPM. Likewise, 1 to
1.9 PPM reads as 1 PPM, etc.
Let's use some numbers. Let's say I have finished a batch of CS
and send half of it to a lab that runs an Atomic Aborption
Spectragraphy. The batch was made with Lab & Tech distilled water
(0 PPM). The test measurement is 10 ppm
I reach for my trusty TDS meter. The meter measures 90 % of the
transconductace (calibrated to Sodium Chloride which has twice
transconductance of CS) so 4.5 only is measured and the
conversion factor has a 50% error (under 100ppm readings) so 2.25,
rounded down becomes 2 PPM.
I have a batch of 30 PPM CS. 15 X 90%= 13.5 microS measured
multiplied by 50% Conversion=6.75 rounded down to 6 ppm
If I have a reading of 3 PPM X 4= 12 PPM (3 times 2 (for
Conversion Factor) times 2 (Salt factor) equals 12 PPM)
This doesn't account for Commerical Distilled water which measures
from 0 to 2 ppm (0 to 4 ppm if taking into account the Conversion
Factor from circuitry). The DW will measure as 0 ppm at levels as
high as 1.9 ppm (actual).
That is why I use the number 4 as a multiplier when using a TDS
meter to measure CS batches.
How accurate do I think these measures are with TDS meters?
Not very accurate, but better than nothing, or shelling out $400
USD everytime I make CS to get an accurate reading.
Regards,
Steve Foss
If you are using Sodium Chloride or Sodium bicarbonate as an
electrolyte this muddies the water (and the measurement) further.
>Question for the group: What multiplier do you use and how
accurate do
you think your measurements are???
Just make sure the TDS meter probe is not contaminated when measuring,
make sure there are no bubbles on the probe tips and do not try to
measure moving water (keep TDS meter still in water).
- Steve
<
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>..
Hi Steve. How does one use a TDS meter? Thanks. Faith G.
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