Hardness as CaCO3


  • Power plants
  • Cooling water
  • Water steam cycle
  • Boiler feedwater
  • Reversed osmosis
  • Ion exchangers
  • Ultrapure water
  • Drinking water


Colorimetric analyzer for the determination of water hardness.


The photometric determination is based on the reaction of calcium ions with an o-cresolphthalein complexone solution, which yields a violet colored complex. The intensity of the color is proportional to the calcium concentration in the sample. The absorbance of the complex is measured at 572 nm.


(Ø 26 mm)
500 ppb
(Ø 16 mm)
1000 ppb
Wavelength 572 nm
Number of reagents 2
Min. analysis time 6 minutes

Technical Specifications

Model 3S-CL
Sampling Mode Batch, with freely settable frequency.
Sample Pressure: Atmospheric
Temperature: 5 ‐ 45°C (41 ‐ 113°F)
Flow Rate: 80 to 500 mL/min
Connection: 6 mm (¼-in.)
Drain Pressure-free drain
Connection: 12 mm (½-in.)
Input Streams 2
Material Epoxy-coated stainless steel AISI 304
Dimensions (H x W x D) 604 x 380 x 210 mm (23.6 x 14.8 x 8.2 in)
Weight 20 kg (44 lbs)
Power Supply Input Voltage: 115 VAC,230 VAC,24 VDC
Power consumption: max. 80 W
Output signals 2 x 4-20 mA analog outputs
Modbus via RS485,Ethernet
Alarms 2 SPDT programmable voltage-free relays
Digital Input None, Online, Start Extra, Skip Idle, Emergency Stop
Ambient Temperature 5 - 45 °C (41 - 113 °F)
Ambient Humidity 10 - 90 % RH (non-condensing)
Protection Grade IP54 (indoor only, outdoor use possible with external cabinet, not included)