Example ccalculation for EC = 1.0 mS/cm:
| Unit | Value |
|---|---|
| S/cm | 0.001 |
| mS/cm | 1.00 |
| µS/cm | 1000 |
| CF | 10 |
| mho/cm | 0.001 |
| mho/m | 0.01 |
| ppm (640-Faktor) | 640 |
Overview: Gängige TDS-Konversionsfaktoren
| Factor | PPM = EC × Factor | Typical use | Comment |
|---|---|---|---|
| 500 | NaCl-Faktor | USA (Hanna), old | Typisch für Trinkwasseranalytik |
| 640 | 442-Faktor | Europa, Kanada, Industrie | Gemisch aus 40% Na₂SO₄, 40% NaHCO₃, 20% NaCl |
| 700 | KCl-Faktor | Australien, Bluelab, USA (z. T.) | Typisch für Düngemittellösungen |
Why these differences?
EC measures conductivity – it is universal (in mS/cm).
TDS is an approximate value in mg/L (ppm), based on a chemical assumption.
Device manufacturers define the factor differently, depending on the salt mixture used for calibration.
EC measures conductivity – it is universal (in mS/cm).
TDS is an approximate value in mg/L (ppm), based on a chemical assumption.
Device manufacturers define the factor differently, depending on the salt mixture used for calibration.