Katarina,
Looking at the graphs of concentration, electrode spacing, and pulsed
DC test results posts you will see an attempt at relating electrode spacing
to conductivity(CS resistance). What I am trying to do is simply say that
if
Ivan's setup(electrodes spaced 1 3/4 inches apart) measures
20Kohms(20,000ohms for 12 - 15ppm) across the electrodes then in my
setup(electrodes 3/4 inch apart) should measure around 15Kohms(15,000) for
12 - 15 ppm.
How to measure CS resistance:
1. Get a volt-ohm-meter(radio shack) that reads in the
milli-ohms range.
2. Measure input voltage at Electrodes. It is easier if
you have a regulated or known voltage source. In other
words if you know your voltage across the electrodes is
12VDC and it doesn't change then no need to measure it.
3. Wipe electrodes
Change you electrode spacing to 1 3/4 inches.
Put electrodes in CS solution.
4. Measure your current(you will need to read you VOM
manual) Ex. The meter displays .6 on the ma(milli-
amp) scale. This is equal to .0006amps.
5. Calculate the CS resistance.
Voltage = CS resistance X Current
12VDC = CS resistance X .0006amps
12/.0006 = CS resistance
20,000 = CS resistance
6. From Ivans graph 20,000 is around 13ppm.
Note: It is easier to move the electrodes and measure,
than not moving the electrodes and guessing.
Since Ivans measurements are at 1 3/4 inches and his
graphs are affected by the spacing it is best to get
as close to his set up as possible when
measurements are taken. Since his graph relates ppm
with CS resistance it is easier to read the graph.
If your CS resistance isn't exactly 20,000ohms look
at my post, graphs of concentrations(resp). The post
shows you how to ball park your ppm if your
resistance is above or below 20,000.
Electrode size and wetted length will affect your
current readings but, for ball parking your ppm the
above method should work fine.
I hope this helps.
BillH
-----Original Message-----
From: Katarina Wittich [mailto:[email protected]]
Sent: Tuesday, November 02, 1999 2:08 PM
To: [email protected]
Subject: CS>Re: Ivan/conductivity meter
Hi Ivan,
I am a silvertail who is definitely interested in the usefulness of a cheap
conductivity meter to measure concentration information on the cs that I am
making ---- but I need some help of a truly non-technical explanation of
what kind of meter to use and how to do so. I get the subject matter of
these interesting and possibly useful posts -- but they are way above my
non-techie head.
Basically, I seem to have found which water and what length of time works
with my generator to make a clear solution with a failry strong tyndall, no
sludge, and a metalic taste. I am assuming I have pretty small particles
since the solution is clear -- so now I would just like to have an idea of
what ppm I've got so I can figure out how much to take. I'll send some in to
Fred to test -- but I'd like to be able to check it out on the occasional
batch at home - so it would be great to learn how to do so.
Thanks so much,
Katarina
> I should think that quite a few silvertails will be interested in the
> outcome of these discussions, if only in that the conclusion may be
> that a cheap conductivity meter can provide reliable concentration
> information for silver colloids or sols fitting certain parameters.
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