Delta OHM HD 8706-R1, Инструкция по эксплуатации

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ENGLISH
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6.2 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 it is shown the conductivity trend of a number of electrolytes
as a function of concentration. If the curve that gives the conductivity as a
function of concentration shows a maximum value, the concentration can-
not be determined for certain because for a given conductivity value there
are two concentration values. In this case the solution must be dissolved
so as to obtain a certain value.
If the solutions contains more than one type of electrolyte, the concentra-
tion of the individual components cannot be determined unless particular
conditions are present.
For example, an acid or a strong base contribute much more than a salt to
the increase in conductivity. Typical examples: regulation of detergent in
industrial washing, regulation of degreasing baths, regulation of galvanic
baths, checking milk, checking fertilizer in irrigation systems, etc.
6.3 CHECKING CONDUCTIVITY IN MULTI-ELECTROLYTE
SOLUTIONS
A conductimetry control often allows the chemical-physical variation of a
solution to be detected. In oceanography the total saline content may be
determined by means of conductivity measurements. In lake or river water
a variation in conductivity is often the sign of pollution due to industrial
waste water.
The hardness of the feeding water for boilers, cooling towers, steam gen-
erators, etc. may be determined approximately by means of conductivity
measurements (in Italy it is sufficient to multiply the conductivity at 20°C by
0.7 to obtain the quantity of equivalent salinity expressed in ppm of
CaCO
3
).
In the food industry the concentration of various saline solutions for pre-
serving food stuffs may be determined by measuring conductivity.
6.4 CONDUCTIVITY OF THE SOIL
It is a known fact that for different types of plants, flowers and cereals there
are optimum soil salinity values. Conductivity measuring allows indirect
determination of the salinity of the soil.
The method adopted by the Italian Society of Science of the Soil is the fol-
lowing:
Take a sample of soil, dry it in the air and ridles it at 2 mm. Dissolve it in
5 times its volume of demineralized water. Stir for about 30 minutes.
Let the liquid rest for few minutes and take the measurement with an