Thermo orion 135A, Инструкция по эксплуатации

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Calibration
solutions
Clean
sensors
Cell constant
4-electrode
sensors
2-electrode
sensors
Models 135A and 136S Portable Conductivity Meters
Operation 11
Calibration
With calibration the Models 135A and 136S are adjusted to
the cell constants of the sensor.
General information on calibration
Solutions for calibration of conductivity meters are un-
buffered systems. Care should be taken to use fresh
conductivity standards and to avoid contamination of the
conductivity standard by water droplets adhering to the
conductivity sensor.
Before calibration, make sure that the conductivity sensor
is clean. Residues should be rinsed off with distilled water.
Afterwards, the sensor should be wiped dry and rinsed with
the calibration solution to be used.
The cell constant is determined by the size and geometric
arrangement of the measuring electrodes. It is the charac-
teristic parameter of conductivity sensors. The cell cons-
tant changes very little over time.
With 4-electrode sensors the principle of separate current/
voltage electrodes results in virtually no measuring errors
even in the case of partial soiling of the measuring elec-
trodes. However, electrodes completely soiled with insulat-
ing coatings cause the measurement to fail.
With 2-electrode sensors for the measurement of low con-
ductivities, e.g. ultrapure water, calibration should be car-
ried out using Thermo Orion 100
m
S Conductivity Standard
(Cat. no. 011008).