HARD-406 Water Hardness Sensor

The Apure HARD-406 all-in-one on-line total hardness sensor uses a PVC membrane based calcium and magnesium ion selective electrode to test the total hardness of water (in terms of CaCO3), with temperature compensation to ensure that the test is fast, simple, accurate and economical.

  • Stable performance
  • Quick installation
  • Long life

With Apure’s calcium and magnesium ion selective electrodes, the internal reference solution exudes extremely slowly from the microporous salt bridge at a pressure of at least 100 KPa (1 Bar). Such a reference system is very stable and the electrode life is longer than that of ordinary industrial electrodes. 3/4 NPT pipe thread for easy countersunk installation or mounting in pipes and tanks.


  • Industrial Wastewater
  • Drinking water
  • Surface water
  • Boiler feedwater
  • Condensate and cooling water
  • Process water
Measuring range0-1000.0mg/L
Resolution0.1mgL, 0.1℃
Accuracy±10% FS, ±0.3℃
Current outputRS-485 (ModbusRTU), 4-20 mA (optional)
Temperature0~40℃, ≤0.2MPa, pH:4~10