Xylem ProLab 3000 LABORATORY pH METER - Manual (Page 178)

Lists ProLab 3000
178 ba75645e02 01/2010
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.
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. Of-
ten, this expression is also used when the measuring system is ad-
justed at the same time (see adjusting).
Channel A channel is an indication on the display that corresponds to a phys-
ical connection at the meter.
The connections for similar sensor types are numbered on the meter
(pH/U/ISE Probe 1, pH/U/ISE Probe 2). To secure the assignment of
connection and channel on the display, the channel is numbered on
the display(e.g. pH1 and U2).
Electrode zero point 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.
Electromotive force of an
electrode
The electromotive force (voltage) U of the electrode is the measur-
able 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 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 transi-
tions.
Measured parameter The measured parameter is the physical dimension determined by
measuring, e. g. pH.
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).
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 elec-
trode zero point. The zero point is part of the offset potential.