Calibration and adjustment CM42-MAA101EBE00
10 Endress+Hauser
2.5 Types of calibration
2.5.1 pH measurement
The following types of calibration are possible:
• Two-point calibration
– With calibration buffers
– Entry of data for the slope, zero point and temperature
• Single-point calibration
– Entry of a reference value
– Sample calibration with laboratory comparative value
• Temperature adjustment by entering a reference value
If using a combined sensor (CPS16D/CPS76D/CPS96D) you must calibrate both the pH
electrode and the ORP electrode to get reliable rH values, for example.
2.5.2 Measuring the ORP
The following types of calibration are possible:
• Two-point calibration with medium samples (only ORP %)
• Single-point calibration with calibration buffer (only ORP mV)
• Data entry of an offset (only ORP mV)
• Temperature adjustment via reference value
2.6 Two-point calibration
2.6.1 General information
Two-point calibration is the preferred method for pH sensors, particularly in the following
applications:
• Municipal and industrial wastewater
• Natural waters and drinking water
• Boiler feedwater and condensates
• Beverages
Calibrating with buffers with pH 7.0 and 4.0 is recommended for most applications.
Alkaline buffer solutions have the disadvantage that carbon dioxide from the air can alter the
pH value of the buffer on the long term. If calibrating with alkaline buffers it is best to do so in
closed systems, such as flow assemblies or retractable assemblies with a rinse chamber, to
minimize the effect of air.
2.6.2 With calibration buffers
pH measurement
You use calibration buffers to perform two-point calibration. The quality buffers supplied
by Endress+Hauser are certified and measured in an accredited laboratory. The
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