wtw pH/Oxi 340i Operating Manual page 74

Lists
Adjusting
Amperometry
Asymmetry
AutoRange
AutoRead
Calibration
D. O. partial pressure
D. O. saturation
Diaphragm
Electrode zero point
Electromotive force of
an electrode
Measured parameter
74
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 with-
in the tolerance.
Name of a measuring technique. The signal (depending on the mea-
sured parameter) of the probe is the electric current. The electrical
voltage remains constant.
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
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 adjust-
ed at the same time (see adjusting).
Pressure caused by the oxygen in a gas mixture or liquid.
Short name for the relative D. O. saturation.
Note: The D. O. saturation value of air-saturated water and the D. O.
saturation value of oxygen-saturated water are different.
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 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 measured parameter is the physical dimension determined by
measuring, e. g. pH, conductivity or D. O. concentration.
pH/Oxi 340i