Thermo Electron 3-Star Conductivity, Руководство пользователя

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Thermo Electron Corporation VII-2 Orion Star Series Meter
Conductivity
Conductivity Linear Temperature Compensation Coefficient:
This menu
will only appear when Linear temperature compensation has been selected.
The conductivity of a solution with a specific electrolyte concentration changes
with temperature. The relationship of the change in conductivity as a function of
temperature is described by a solution’s temperature coefficient. Temperature
coefficients vary with each solution. Some examples are shown in Table 1. This
Meter uses 2.1%/˚C as the default linear temperature coefficient, which is
representative of many aqueous samples, to compensate for temperature changes.
The meter has an adjustable temperature coefficient of 0.0 to 10.0%/˚C
Table 1
Typical Temperature Coefficients Between 25 and 50 ûC (Percent change of
Conductivity per ûC)
Solution %/˚C
Ultrapure Water 4.55
Salt (NaCl) Solutions 2.12
5% NaOH 1.72
Dilute Ammonia 1.88
10% HCl 1.32
5% Sulfuric Acid 0.96
98% Sulfuric Acid 2.84
Sugar Syrup 5.64
Conductivity TDS Factor:
Total Dissolved Solids (TDS) refers to the dissolved
inorganics in a solution. These dissolved inorganics will carry a current and will be
reflected as a conductivity reading. Since a relationship can be shown between
conductivity and TDS, a conductivity reading can be used as an estimation of the
presence of inorganics.
The standard method of determining TDS (Total Dissolved Solids) is by evaporating
the sample to dryness at 180 ˚C and weighing the residue. After evaporating the
sample, one would have to calculate a specific “factor” for the solution by taking
the TDS value obtained in weighing and dividing it by the conductivity of the sample.
This factor would then be multiplied by the subsequent conductivity readings to
obtain the TDS value of the sample as referenced in Standard Methods for Water
and Wastewater.