Xylem HandyLab 600 - Manual (Page 66)

Glossary HandyLab 600
66 ba77064e01 03/2014
14 Glossary
pH/ORP
General information
Asymmetry see zero point
Junction The junction is a porous body in the housing wall of reference elec-
trodes or electrolyte bridges. It arranges the electrical contact between
two solutions and makes the electrolyte exchange more difficult. The
expression, junction, is also used for ground or junction-less transitions.
Electromotive force of
an electrode
The electromotive force U of the electrode is the measurable electromo-
tive force of an electrode in a solution. It equals the sum of all the gal-
vanic voltages of the electrode. Its dependency on the pH results in the
electrode function, which is characterized by the parameters, slope and
zero point.
Zero point The zero point of a pH electrode is the pH value at which the electromo-
tive force of the pH electrode at a specified temperature is zero. Nor-
mally, this is at 25 °C.
pH value The pH value is a measure of the acidic or basic effect of an aqueous
solution. It corresponds to the negative decadic logarithm of the molal
hydrogen ions activity divided by the unit of the molality. The practical
pH value is the value of a pH measurement.
Potentiometry Name of a measuring technique. The signal (depending on the mea-
sured parameter) of the electrode is the electrical potential. The electri-
cal current remains constant.
ORP
(U)
The ORP is caused by oxidizing or reducing substances dissolved in
water if these substances become effective on an electrode surface
(e.g. a gold or platinum surface).
Slope The slope of a linear calibration function.
Resolution Smallest difference between two measured values that can be dis-
played by a meter.
AutoRange Name of the automatic selection of the measuring range.
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.
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).
Measured parameter The measured parameter is the physical dimension determined by
measuring, e.g. pH, conductivity or D.O. concentration.