Walchem WebMaster ONE Instruction Manual page 67

You then be prompted to "Please Rinse the Electrode". Do so, and then click "Continue".
You will now be prompted to type in the value of the buffer being used. Do so, and then click
"Continue".
You will now see the mV output from the electrode. When this value is stable, click "Continue".
The WebMasterONE will either pass or fail the calibration, and prompt you to return the electrode
to the process. Click "Continue" when you are ready for pH control to resume.
If the calibration fails for any reason, refer to Section 8 for troubleshooting help.
1 Point Process Calibration
The new window will display the current value of the pH, using the last calibration. Measure the
pH of a sample of the water using a handheld meter, and type the new pH value in the text box.
Click the "Continue" button.
The WebMasterONE will either pass or fail the calibration. Control of the pH will continue
throughout this process.
If the calibration fails for any reason, refer to Section 8 for troubleshooting help.
Status
Possible status messages are; Normal (everything is OK), Sensor Error (the signal is not valid),
High Alarm, Low Alarm, Circuit Board Failure (for Sensors 2, 3 or 4) or Calibration Time. See
section 8.1 for a complete description of error messages.
Date of Last Calibration
This section is for information only, and lets you know when the last calibration occurred.
Calibration Reminder
If you want to be reminded when the sensor needs calibration, for example every 30 days then type
the desired number of days between calibration in the text box. A value of zero means you will
never be reminded. The highest value allowed is 365 days.
Self Test
The Self Test is used to check the circuitry of the pH input. Click on the "Self Test" button, and
the controller will display either Pass or Fail, and also readings of a simulated pH and temperature.
If the controller passes self test, and you are having problems reading the correct pH or calibrating,
then the problem must be with the electrode, wiring or installation.
Uncalibrated mV
Displays the mV signal from the pH electrode in the current sample. This is useful for
troubleshooting.
Calculated Slope
This displays the slope (change in the mV output of the pH electrode per pH unit) of the pH
electrode as of the last calibration. A perfect electrode will change by approximately 59 mV per
pH unit. This is helpful for troubleshooting, and also to predict when the electrode may need to be
replaced.
63