MODEL 54e pH/ORP

SECTION 4.0

 

CALIBRATION

SECTION 4.0

CALIBRATION

The following procedures are described in this section:

Temperature Calibration (Section 4.1)

Auto Buffer (Two-Point) Calibration (Section 4.2)

Manual Two-Point Calibration (Section 4.3)

Single-Point pH Calibration (Section 4.4)

Temperature Compensation Options (Section 4.5)

pH Slope Adjustment (Section 4.6)

Hold Mode (Section 4.7)

INTRODUCTION

Calibration is the process of adjusting or standardizing the controller to a lab test (such as free acid titration) or a calibrated laboratory instrument, or standardizing to some known reference (such as a commercial pH buffer). Calibration ensures that the controller shows an accurate, and therefore, repeatable reading of pH or temperature.

Since pH measurements are affected by temperature, the Model 54e pH/ORP reads the temperature at the sensor and compensates for the changing temperature by referencing all pH measurements to 25°C (77 °F).

This compensates for temperature-related changes in the response of the glass pH electrode which would affect the pH measurement. The pH temperature com- pensation does not account for changes in chemical activity which affect the actual pH value of the solution being measured. See Section 7.0 for information on solution temperature compensation.

To ensure the controller's accuracy, it is important to perform all the calibration procedures provided in this section if you are:

installing this unit for the first time

changing or replacing electrodes or sensor ele- ments

troubleshooting

IMPORTANT

Before attempting to calibrate, inspect the pH sensor assembly. It must be clean, undamaged and free from cracks or other signs of leakage or wear.

WARNINGS

Before performing any of these procedures, be sure to disable or disconnect the chemical feed pumps or other external devices (see placing controller in hold, Section 4.7)

Perform the calibration procedures in this section only in the order they are given.

Do not attempt to calibrate the controller if the fault LED is lit or the display is showing fault messages.

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Emerson 54e pH/ORP instruction manual Section Calibration, Introduction