Hach Ultra POLYMETRON 9125, Руководство оператора

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Transmitter 9125 – Conductivity / resistivity measurement
Page 4
Introduction
The 9125 transmitter is a user-friendly instrument
(installation, programming), equipped with a
microprocessor it can be configured to correspond to
any application in the following sectors :
x
drinking water,
x
waste water,
x
process (chemistry, paper mills, sugar mills...),
x
measurement in pure/ultrapure water (energy
power plants, semiconductor industry, chemistry).
The 9125 transmitter should be connected to a probe
via a cable.
Conductivity measurement
The electric conductivity measures the transport of
electric charges in any field. In metal conductors, the
current flows by transport of electrons, whereas in
solutions, it flows by transport of ions such as Na+ and
Cl- which ensure the transport of charges. The higher
the transport of charges is, the greater is the
conductance of the solution.
Conductivity is the capacity a solution has to
conduct current.
In solution, conductivity is much more complicated
than in conductors because several species ensure
the transport of charges. For instance, in drinking
water the conductive species registered are sodium,
calcium, magnesium, ferrous cations, ferrites,
phosphates and nitrate ions. For slightly concentrated
solutions, the concentration of H
+
protons and hydroxyl
OH
-
ions (stemming from the weak dissociation of the
water [H
+
] = [OH
-
] = 10
-7
mol/l to 25°C) can no
longer be neglected in the presence of the product,
this therefore leads to a non-linear variation
Conductivity/Concentration.
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