wtw Multi 9420 - Page 127

Multi 9420 Glossary
ba75964e04 04/2015 127
Dissolved oxygen
General information
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 prac-
tice, this dimension cannot be measured directly. Therefore, the practi-
cal salinity according to IOT is used for oceanographic monitoring. It is
determined by measuring the electrical conductivity.
Salt content General designation for the quantity of salt dissolved in water.
Temperature
coefficient
Value of the slope of a linear temperature function.
Temperature
compensation
Name of a function that considers the temperature influence on the
measurement and converts it accordingly. Depending on the measured
parameter to be determined, the temperature compensation functions
in different ways. For conductimetric measurements, the measured
value is converted to a defined reference temperature. For potentiomet-
ric measurements, the slope value is adjusted to the temperature of the
test sample but the measured value is not converted.
α
T
Ref
=
Meas
*
1
1+
a
(T - )
*
T
Ref
D.O. partial pressure Pressure caused by the oxygen in a gas mixture or liquid.
D.O. % saturation Short name for the relative D.O. saturation.
OxiCal
®
WTW name for a procedure to calibrate D.O. measuring systems in
water vapor saturated air.
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 according to IOT is used for oceanographic monitor-
ing. It is determined by measuring the electrical conductivity.
Salt content General designation for the quantity of salt dissolved in water.
Slope (relative) Designation used by WTW in the D.O. measuring technique. It
expresses the relation of the slope value to the value of a theoretical
reference sensor of the same construction type.
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.
AutoRange Name of the automatic selection of the measuring range.