LaMotte CON 6 PLUS, Руководство пользователя

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particularly where high purity water is involved. The unit most
often used to describe resistivity is megohm-cm, which are simply
the reciprocal of conductivity ( μ S/cm). The chart below shows the
relationship between these units.
Conductivity
( μ S/cm)
Resistivity
(megohm-cm)
0.056 18
0.1 10
1.0 1.0
2.5 0.4
10.0 0.1
Conductivity and Temperature
Conductivity in aqueous solutions re fl ects the concentration, mobility,
and charge of the ions in solution. The conductivity of a solution will
increase with increasing temperature, as many phenomena in fl uencing
conductivity such as solution viscosity are a ff ected by temperature.
The relationship between conductivity and temperature is predictable
and usually expressed as relative % change per degree centigrade.
This temperature coe ffi cient (% change per degree) depends on the
composition of the solution being measured. However, for most medium
range salt concentrations in water, 2% per degree works well. Extremely
pure water exhibits a temperature coe ffi cient of 5.2%, and concentrated
salt solutions about 1.5%.
Since temperature a
ff ects the conductivity measurement so profoundly,
the usual practice is to reference the conductivity to a standard
temperature—typically 25 °C. Select 20 °C or 25 °C as the normalization
temperature in advanced setup.
Enter the temperature coe
ffi cient which best suits the sample and use an
ATC probe to automatically temperature compensate back to the chosen
reference temperature.