ENDRESS+HAUSER  CPS16D-7AT2C

• Long-term monitoring or limit control in processes with stable process conditions
  • Chemical processes
  • Pulp and paper industry
  • Power stations (e.g. flue gas cleaning)
  • Incinerator plants
  • Mining
  • Wastewater
• Water treatment
  • Drinking water
  • Cooling water
  • Well water

With ATEX, IEC, FM and CSA approval for use in hazardous areas.

• Simultaneous measurement of pH, ORP and rH value (in rH mode)
• Additional electrode made of platinum, for measuring reference impedance
• Low-maintenance and robust thanks to large PTFE ring junction
• Can be used at pressures up to 17 bar (246 psi), absolute
• Process glass also for very alkaline applications
• Integrated temperature sensor for effective temperature compensation
• Long service life thanks to poison-resistant reference with ion trap
• Glass breakage and blockage detection by measuring:
  • Resistance of glass membrane
  • Reference impedance

• Maximum process safety owing to non-contact, inductive signal transmission
• Data security thanks to digital data transmission
• Very easy to use as sensor data saved in the sensor
• Predictive maintenance possible as sensor load data logged in the sensor

The pH value is used as a unit of measurement for the acidity or alkalinity of a liquid medium. The membrane glass of the electrode supplies an electrochemical potential which is dependent upon the pH value of the medium. This potential is generated by the selective penetration of H + ions through the outer layer of the membrane. An electrochemical boundary layer with an electric potential forms at this point. An integrated Ag/AgCl reference system serves as the required reference electrode. The transmitter converts the measured voltage into the corresponding pH value using the Nernst equation.

The ORP potential is a unit of measurement for the state of equilibria between oxidizing and reducing components of a medium. The ORP is measured using a platinum or gold electrode instead of the pH-sensitive glass membrane. Analog to the pH measurement, an integrated Ag/AgCl reference system is used as a reference electrode.

The rH value is defined as the negative logarithm of partial pressure of hydrogen in a solution. The pH value and ORP value of a solution must be measured simultaneously to calculate the rH value. The value is calculated using the following equation:

rH = 2 . (mV/S) + 2 pH
pH = measured pH value
mV = measured ORP value in mV + 207 mV (Ag/AgCl system)
S = slope of pH electrode

The rH value is an indicator of the oxidation or reducing ability of a process solution. The measuring range is from 0 to 42. A process medium with rH values between 0 and 9 has a high reducing ability; a low reducing ability with rH 9-17; an indeterminate ability with rH 17-25; a low oxidation ability with rH 25-34, and a high oxidation ability with rH 34-42.