Xylem Lab 850, up to serial number 09470314 - Manual (Page 53)

Lab 850 Lists
53 ba75553e03 01/2006
Glossary
Asymmetry see zero point
Resolution Smallest difference between two measured values that can be
displayed by a meter.
AutoRange Name of the automatic selection of the measuring range.
Junction The junction is a porous body in the housing wall of reference
electrodes 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.
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).
Electromotive force of
an electrode
The electromotive force (voltage) 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.
Measured variable The measured parameter is the physical dimension determined by
measuring, e. g. pH, conductivity or DO concentration.
Test sample Designation of the test sample ready to be measured. Normally, a test
sample is made by processing the original sample. The test sample
and original sample are identical if the test sample was not processed.
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.
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.
pH value The pH 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.