Cell Type; Tds Factor; Salinity Type - Thermo Scientific Orion Versa Star Pro User Manual

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Appendix A Channel Specific Settings and Features
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144 Orion Versa Star Pro Meter User Manual

Cell Type

The Versa Star Pro meter with conductivity module accepts 2-cell and 4-cell conductivity probes
and allows the type of conductivity probe to be set as Standard (most conductivity probes) or
USP (for the ultra-pure water conductivity probe, Catalog Number 013016MD, when disabling
temperature compensation).

TDS Factor

The Versa Star Pro meter with conductivity module measures TDS as the total amount of
dissolved inorganic material in a solution. The dissolved inorganic material carries 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 inorganic material using
the TDS factor entered in the setup menu.
The standard method of determining TDS involves evaporating a sample to dryness at 180 °C
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.

Salinity Type

The Versa Star Pro meter with conductivity module offers two salinity types: practical salinity
and natural sea water. Practical salinity measurements are based on relating the sample
measurement to the reading of a standard potassium chloride (KCl) solution at 15 °C. The
Versa Star Pro meter with conductivity module will automatically temperature compensate and
report the expected practical salinity result as practical salinity units (psu) at 15 °C when using
a conductivity probe with built-in temperature sensor. Natural sea water measurements use a
historic convention known as UNESCO 1966 and the Versa Star Pro meter with conductivity
module will report the expected natural sea water result as parts per thousand (ppt) .
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