Delta OHM HD 9213-R1, Инструкция по эксплуатации

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APPLICATIONS OF CONDUCTIVITY MEASUREMENTS
It must always be remembered that the conductivity of a liquid is proportio-
nal to the total amount of dissolved substances and not to one specific
substance. Despite this there are many applications of conductivity, espe-
cially for quality controls.
CHECKING IMPURITIES IN WATER
The most frequent applications are in the demineralization of water, by
distillation, ionic exchange or inverse osmosis. Of course it is not possible
to measure impurities that do not contribute to conductivity, such as sand,
oil, micro-organisms, etc. Good distilled water should have a conductivity
of less than a few µS.
An interesting application is the determination of impurities in sugar. Sugar
is not an electrolyte and does not contribute to a variation of conductivity if
it is dissolved in demineralized water, but impurities do.
DETERMINING THE CONCENTRATION OF A SOLUTION
If there is only one electrolyte in a solution, its concentration may be deter-
mined by measuring the conductivity. For example, the graphs above show
the conductivity trend of a number of electrolytes as a function of concen-
tration. If the curve that gives the conductivity as a function of concentra-
tion shows a maximum value, the concentration cannot be determined for
certain because for a given conductivity value there are two concentration
values. In this case the solution must be dissolved so at so obtain a certain
value. If the solution contains more than one type of electrolyte, the con-
centration of the individual components cannot be determined unless parti-
cular conditions are present. For example, an acid or a strong base contri-
bute much more than a salt to the increase in conductivity. Typical exam-
ples: regulation of detergent in industrial washing, regulation of degreasing
baths, regulation of galvanic baths, checking milk, checking fertilizer in irri-
gation systems, etc.
ENGLISH
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