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6. Analog input – conductivity and TDS measurement
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Dr. A. Kuntze
I
Gutes Wasser mit System
Robert-Bosch-Str. 7a
40668 Meerbusch
+49 (0) 2150-7066-0 / Fax -60
www.kuntze.com
TDS unit
The TDS value is the untiy of soluted organic and anorganic compunds in a solvent. Common unit for
TDS is ppt (parts per thousand), ppm (parts per million) and ppb (parts per billion).
The unit depends on the measuring range
Measuring range
µg/l = ppb
mg/l = ppm
g/l = ppt
0-2.000 µS/cm
0-1000
0-1.000
0-20.00 µS/cm
0-10.00
0-200.0 µS/cm
0-100.0
0-2.000 mS/cm
0-1000
0-1.000
0-20.00 mS/cm
0-10.00
0-200.0 mS/cm
0-100.0
TDS factor
If you choose TDS the complete conductivity will be converted in TDS by an adjustable factor. The
TDS determination via conductivity mainly informs about the salinity of the solution because only
solved salts contribute to the conductivity. This is an approximation which you can adjust to the real
conditions by changing the factor. A factor of 0.5 is recommended for a pure sodium chloride solution.