Thermo Scientific Orion Versa Star, Справочное руководство

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Thermo Scientific Orion VERSA STAR Conductivity/Temperature Module
Appendix Advanced Features
Conductivity Temperature Compensation and Reference Temperature
The Orion VERSA STAR Meter with Conductivity/Temperature Module Systems have the ability to use a temperature
compensation feature that calculates and displays the conductivity measurements at a reference temperature of 5 °C,
10 °C, 15 °C, 20 °C or 25 °C. The temperature compensation can be turned off or set to Linear, nLFn (non-linear natural
non-degassed water), nLFu (non-linear ultra pure degassed water) or EP (temperature compensation off and warning is
displayed if conductivity values are outside EP requirements for ultra pure water). The closer the sample temperature is
to the selected reference temperature, the more accurate the conductivity measurement will be, especially if the
temperature compensation coefficient is estimated or inaccurate. The conductivity of a solution with a specific electrolyte
concentration changes with temperature and this relationship is described by the temperature coefficient of the solution.
The meter has a default temperature coefficient of 2.1 percent change in conductivity per ºC, which is representative of
many aqueous samples.
Solution (25 °C to 50 °C) Temperature Coefficient (% / °C)
Ultra Pure Water 4.55
Salt (NaCl) 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 and Total Dissolved Solids (TDS)
The Orion VERSA STAR Meter with Conductivity/Temperature Module Systems measure TDS as the total amount of
dissolved inorganics in a solution. The dissolved inorganics carry a current that is measured by the conductivity probe.
Since there is a direct relationship between conductivity and TDS, conductivity readings are used to estimate the
presence of inorganics. The user must enter a TDS factor between 0.01 and 10 mg/L in the setup menu.
The standard method of determining TDS involves evaporating a sample to dryness at 180 ºC and weighing the residue.
The TDS factor is calculated by taking the residue weight and dividing it by the sample conductivity. Subsequent
conductivity readings are multiplied by the TDS factor to determine the TDS value of the sample.
Conductivity Automatic Calibration
The Orion VERSA STAR Meter with Conductivity/Temperature Module Systems are capable of automatically
recognizing Thermo Scientific Orion 100 μS/cm (Cat. No. 011008), 1413 μS/cm (Cat. No. 011007 and 01100710) and
12.9 mS/cm (Cat. No. 011006 and 01100610) conductivity standards when the nominal cell constant of the conductivity
cell is entered in the setup menu.