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pHotoFlex
pH
Adjusting
Asymmetry
AutoRange
AutoRead
Calibration
Electrode zero point
Electromotive force of
an electrode
Junction
Measured parameter
Measured value
Measuring system
Molality
MultiCal
ba75975e05
10/2017
Glossary
To manipulate a measuring system so that the relevant value (e. g. the
displayed value) differs as little as possible from the correct value or a
value that is regarded as correct, or that the difference remains within
the tolerance.
Designation for the offset potential of a pH electrode. It is the measur-
able potential of a symmetrical electrode, the membrane of which is
immersed in a solution with the pH of the nominal electrode zero point
(WTW electrodes: pH = 7).
Name of the automatic selection of the measuring range.
WTW name for a function to check the stability of the measured value.
Comparing the value from a measuring system (e. g. the displayed val-
ue) to the correct value or a value that is regarded as correct. Often,
this expression is also used when the measuring system is adjusted at
the same time (see adjusting).
The zero point of a pH electrode is the pH value at which the electro-
motive force of the pH electrode at a specified temperature is zero.
Normally, this is at 25 °C.
The electromotive force U of the electrode is the measurable electro-
motive force of an electrode in a solution. It equals the sum of all the
galvanic voltages of the electrode. Its dependency on the pH results in
the electrode function which is characterized by the parameters, slope
and zero point.
The junction is a porous body in the housing wall of reference elec-
trodes or electrolyte bridges. It forms the electrical contact between
two solutions and makes electrolyte exchange more difficult. The ex-
pression, junction, is also used for ground or junction-less transitions.
The measured parameter is the physical dimension determined by
measuring, e. g. pH, conductivity or DO concentration.
The measured value is the special value of a measured parameter to
be determined. It is given as a combination of the numerical value and
unit (e. g. 3 m; 0.5 s; 5.2 A; 373.15 K).
The measuring system comprises all the devices used for measuring,
e. g. meter and sensor. In addition, there is the cable and possibly an
amplifier, terminal strip and armature.
Molality is the quantity (in Mol) of a dissolved substance in 1000 g sol-
vent.
®
WTW name stating that a meter provides several pH calibration pro-
cedures.
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