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Digital ISE combination sensor for ammonium and nitrate

WTW sensors - digital ISE combination sensor (ammonium/nitrate)

Ion selective measurement of ammonium and nitrate free of reagents with automatic compensation of potassium/chloride with the VARiON® Plus 700 IQ

  • Ammonium and nitrate measurement directly in the process
  • Simultaneous compensation of potassium, chloride
  • No sampling, reagent-free
  • Calibration free, long-term stability

These especially stable electrodes ensure long operation times and a simple cleaning method. To measure, simply install the respective electrode into the IQ Sensor Net, everything else will take place automatically. In the measured value display, the values that have already been compensated, are displayed, you can select potassium or chloride output. These values also stand for the signal output per 0/4-20 mA output or digital output (Profibus, Modbus RTU, Ethernet/IP, Modbus TCP) is directly available.

New: Measurement of media with high ammonium load

When thickening or dehydrating wastewater treatment sludge, the so-called centrate water is generated. This water has an especially high amonium content. The centrate water is not drained but rerouted into the wastewater circuit of the system or directly broken down into elementary nitrogen (deammonification). In both cases, the determination of the NH4 freight is very important for an optimal process run. High NH4 concentrations of up to 2000 mg/l can now be determined directly in the medium by means of the Varion®Plus 700 IQ, in centrate water as well as in process waters!


Model Description Order no.
Please order the sensor cable SACIQ separately
VARiON®Plus 700 IQ Digital sensor for the ion selective measurement of ammonium and nitrate, without electrodes 107040
VARiON®Plus A comp SET NH4 VARiON®Plus 700 IQ, reference electrode VARiON® Ref, ammonium measuring electrode VARiON®Plus NH4 and compensation electrode VARiON®Plus K (potassium) 107060
VARiON®Plus N comp SET NO3 VARiON®Plus 700 IQ, VARiON® Ref, VARiON®Plus NO3 and VARiON®Plus Cl (chloride) 107062
VARiON®Plus AN/A comp SET NH4 & NO3 VARiON®Plus 700 IQ, VARiON®Ref, VARiON®Plus NH4 and VARiON®Plus NO3, VARiON®Plus K (potassium) 107066
VARiON®Plus AN/N comp SET NH4 & NO3 VARiON®Plus 700 IQ, VARiON®Ref, VARiON®Plus NH4 and VARiON®Plus NO3, VARiON®PlusCl (chloride) 107068

Technical Data

Ammonium measurement
Integratable measuring chains Reference
Measuring electrode
VARiON®Plus Ref
Measuring ranges / resolution NH4-N
1 ... 2.000 mg/l / 1 mg/l; 0.1 ... 100 mg/l / 0.1 mg/l
1 ... 2,580 mg/l / 1 mg/l; 0.1 ... 129.0 mg/l / 0.1 mg/l
Compensation ranges K+ 1 ...1.000 mg/l / 1 mg/l
Nitrate measurement
Integratable measuring chains Reference
Measuring electrode
VARiON®Plus Ref
VARiON®Plus Cl
Measuring ranges / resolution NO3-N
1 … 1.000 mg/l / 1 mg/l; 0.1 ... 100 mg/l / 0.1 mg/l
5 … 4.500 mg/l / 1 mg/l; 0.5 ... 450.0 mg/l / 0.1 mg/l
Compensation ranges CI- 1 ...1.000 mg/l / 1 mg/l
Temperature measurements and compensation integrated NTC

0 °C … +40 °C
±0.5 K
0.1 K, t95 < 20 s


Model Description Order no.
VARiON® Ref Reference electrode 107042
VARiON®Plus NH4 Ammonium electrode 107044
VARiON®Plus NO3 Nitrate electrode 107045
VARiON®Plus K Potassium electrode 107046
VARiON®Plus Cl Chloride electrode 107047
VARiON®/ES-1 Combination standard 1 (low concentration), 1000 ml 107050
VARiON®/ES-2 Combination standard 2 (high concentration), 1000 ml 107052
VARiON® 700 IQ-SK protective basket for ISE electrodes 107056
VARiON®/Epack Spare parts set: 1 special socket wrench, 1 blind plug, 3 replacement gaskets for electrodes and 1 storage container for the moist storage of the electrodes 107057
DIQ/CHV Dual IQ/Cleaning Head Valve for system 282/284 472007
MIQ/CHV PLUS Module IQ/Cleaning Head for system 2020 480018
Cleaning Air Box - 115 VAC Air pressure compressor, 115 VAC 480017
Cleaning Air Box - 230 VAC Air pressure compressor, 230 VAC 480019
CH Cleaning head 900107


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