wtw Multi 350i, Operating Manual

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Multi 350i Lists
99
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).
Measured variable The measured parameter is the physical dimension determined by
measuring, e. g. pH, conductivity or DO concentration.
Measuring system The measuring system comprises all the devices used for measuring,
e. g. measuring instrument and sensor. 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 sol-
vent.
MultiCal
®
WTW name stating that a measuring instrument provides several cal-
ibration procedures.
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.
ORP voltage 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).
OxiCal
®
WTW name for a procedure to calibrate DO measuring systems in wa-
ter vapor saturated air.
pH value The pH is a measure of the acidic or basic effect of an aqueous solu-
tion. It corresponds to the negative decadic logarithm of the molal hy-
drogen 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 elec-
trical current remains constant.
Reference
temperature
Fixed temperature value to compare temperature-dependent mea-
sured values. For conductivity measurements, the measured value is
converted to a conductivity value at a reference temperature of 20 °C
or 25 °C.
Reset Restoring the original condition of all settings of a measuring system.
Resistance Short name for the specific electrolytic resistance. It corresponds to
the reciprocal value of the electrical conductivity.
Resolution Smallest difference between two measured values that can be dis-
played by a measuring instrument.