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Xylem handylab pH LF 12 User Manual

Page 75

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handylab pH/LF 12

Lists

75

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11/2009

Measuring system

The measuring system comprises all the devices used for measuring,
e. g. measuring instrument and probe. 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

®

Name stating that a measuring instrument provides several calibration
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).

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.

Salinity

The absolute salinity S

A

of seawater corresponds to the relationship

of the mass of dissolved salts to the mass of the solution (in g/Kg). In
practice, this dimension cannot be measured directly. Therefore, the
practical salinity is used for oceanographic monitoring. It is deter-
mined by measuring the electrical conductivity.

Salt content

General designation for the quantity of salt dissolved in water.

Slope

The slope of a linear calibration function.

Standard solution

The standard solution is a solution where the measured value is
known by definition. It is used to calibrate a measuring system.

Temperature

coefficient

Value of the slope of a linear temperature function.