Xylem VARIO WATERPROOF PH METER - Manual (Page 51)

VARIO pH Lists
51 ba75373e04 07/2006
Glossary
Adjusting 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.
Asymmetry Designation for the offset potential of a pH electrode. The measurable
potential of a symmetrical electrode, the membrane of which is immersed in
a solution with the pH of the nominal electrode zero point. For WTW
electrodes, the pH of the nominal electrode zero point is pH 7.
AutoRead WTW name for a function to check the stability of the measured value.
Calibration Comparing the value from a measuring system (e. g. the displayed value)
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).
Electrode zero
point
The zero point of a pH electrode is the pH value at which the electromotive
force of the pH electrode at a specified temperature is zero. Normally, this
is at 25 °C.
Electromotive
force of an
electrode
The electromotive force U of the electrode is the measurable electromotive
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.
Junction The junction is a porous body in the housing wall of reference electrodes or
electrolyte bridges. It forms the electrical contact between two solutions and
makes electrolyte exchange more difficult. The expression, junction, is also
used for ground or junction-less transitions.
Measured
parameter
The measured parameter is the physical dimension determined by
measuring, e. g. pH, conductivity or D. O. concentration.
Measured value 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).
Measuring system The measuring system comprises all the devices used for measuring, e. g.
meter and probe. In addition, there is the cable and possibly an amplifier,
terminal strip and armature.
Molality Molality is the quantity (in Mol) of a dissolved substance in 1000 g solvent.
Offset potential The measurable potential of a symmetrical electrode, the membrane of
which is immersed in a solution with the pH of the nominal electrode zero
point. The asymmetry is part of the offset potential.