Hi Steve,
First off; I am NOT an expert. However I do have some experience.
That said.........
I suspect you have 19 PPM or thereabouts. Well, within 10-15% anyway. As
you know we sell the PWT and advertise it as being within 10% when reading
CS made with our generator. Since your results were from a constant
current source and the current delivered was about the same as our
generators produce, it seems to me the results should correlate. I'm not
sure about the starting voltage but current limiting is still the same as
what we do. We start out with about 38-40 volts but as I see it your
generator setup would just get up to speed much quicker. I assume the
voltage dropped very rapidly soon after you started the process and came
down to the 25-30 volt range quickly. And then slowly dropped to the end
point of 8 volts.
The one difference I do see is that we use 1/4" wide electrodes and you
used #12 wire. Not sure if that would make much difference, but it
could. We use wetted depth of about 4+ inches. Our voltage at the end of
what is read as a 20 PPM batch is about 7 volts across the electrodes so it
seems close enough to me to be comparable.
I'm sure there are some who will say I'm wrong but we had samples analyzed
using the atomic absorption method and the result was that our PWT readings
correlated to those test readings within about 10%. That's why I stand by
the PWT as being the best PPM indicator for the average person. It is very
affordable and repeatable. And after all we're only talking about a very
small quantity of silver in a liter of water.
For those who don't know, the definition of PPM is 1 milligram of silver in
1 liter of water. A small quantity indeed!
The weak Tyndall is exactly what we get using the current value you
use. We attribute it to low constant current and the stirring of the water
during production. Our units also stir at 30 RPM.
The only thing you didn't mention was the quantity of water used. Our
generator is calibrated for a pint but will also make a quart and end up
with about the same PPM and Tyndall. We sometimes make a half gallon at
time but it takes considerably longer to get up to speed with the voltage
we use. I suspect your higher voltage unit would get the process going much
quicker in a larger volume of water.
I would trust the PWT readings. However there is a caveat. The Hanna
information says take about 50% of the reading. They may be correct for
undigested silver but we had our AA tests run using digested and undigested
samples. Digested samples came out about the same as AA readings and
undigested samples came out reading about 55% of the AA tests when tested
with the PWT. So, Hanna and we are both right.
I think you have a very good end product as attested to by the very weak
Tyndall. For those who are new to the list, weak Tyndall is good because
it means there are many more individual silver particles in the water. And
the more particles there are, the better the chances of CS coming in
contact with bacteria and virus. After all it is a numbers game. And of
course particle size is important because smaller IS better in this case.
I'd keep on doing exactly what you're doing Steve.
Trem
www.silvergen.com
Constant Current Colloid Generators
At 10:22 PM 9/2/00 -0600, you wrote:
To the list CS experts:
I would like your opinion on the approximate PPM for the following CS:
Started with 1.1 uS distilled water as measured by Hanna PWT (model HI 98308)
Constant current of 1.0 Ma. DC throughout the entire run.
Starting voltage to the electrodes = 150 VDC
Ending voltage after 3 1/3 hours = 8 VDC. This would be a resistance of 8K.
Ending uS of 19.1 after sitting for a day so agglomeration effects would
settle down
Constant stirring at 30 RPM
Faint TE which can only be seen in a dark room, so I believe the particles
are quite small
Electrodes are both #12 silver wire spaced 1.75 inch and immersed 3.75 inches
So, ladies and gentlemen, about what strength CS have I made? What is the
basis for your estimate?
Thanks for your help,
--Steve Young
