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Q: What is conductivity used to measure?
A: Conductivity
is used to measure the amount of dissolved solids in a solution
or the concentration of acid or base.
Q: How does conductivity work?
A: This can be a
somewhat complex answer. A conductivity sensor has
a known AC voltage passed from a "sending" side, through
the solution being measured, and out to the "receiving"
side. The current in the circuit is measured. Using
Ohm's Law, V = IR, R, the "Resistance" across the water
is calculated. Conductivity is = 1/R. For more details please go
to Conductivity
Technical Education
Q: What are the units of conductivity?
A: Depending on
the range, conductivity is expressed in µS (microSiemens)
or mS (milliSiemens). When very low conductivity is measured,
(if <0.1µS) it is often expressed as resistivity (Megaohms)
rather than conductivity. In the past, conductivity was expressed
as in micromhos or millimhos. The mhos units are now expressed
in Siemens or fractions of Siemens.
Q: Does temperature affect conductivity?
A: Conductivity
is greatly affected by temperature. An error of 2 - 5% per
degree Centigrade is common and depends on the range of conductivity
being measured. Generally, 2% error is most common for above
500uS. Lower conductivity especially values expressed as resistivity
(ultra-pure water = 18.2 Megaohms = 0.055 uS) have up to 5% error.
Your conductivity instrument will make these corrections automatically
if a temperature sensor is used.
Q: How do I choose the proper sensor for my
application?
A: This can be a
daunting question, but can be simplified greatly to make choosing
easier.
Please visit our
conductivity electrode product selection guide.
Q: How do I clean my conductivity electrode?
A: Use mild cleaning
agents such as detergents or 5% HCl (removes scaling deposits). Always soak electrodes in chemicals
and do not use toothbrush or wire brushes
to clean since these will effect electrode performance. |
