Walchem WebMaster ONE Instruction Manual page 71

You will now be prompted to type in the value of the standard solution 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 ORP 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 ORP, using the last calibration. Measure the
ORP of a sample of the water using a handheld meter, and type the new ORP value in the text box.
Click the "Continue" button.
The WebMasterONE will either pass or fail the calibration. Control of the ORP 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 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 electrode 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 ORP input. Click on the "Self Test" button, and
the controller will display either Pass or Fail, and also readings of a simulated ORP. If the
controller passes self test, and you are having problems reading the correct ORP or calibrating,
then the problem must be with the electrode, wiring or installation.
Uncalibrated Reading
Displays the mV signal from the ORP electrode in the current sample prior to calibration. This is
useful for troubleshooting.
Calculated Slope
This displays the slope (change in the mV output of the ORP electrode per expected mV change)
of the ORP electrode as of the last calibration. A perfect electrode will have a slope of 1.000. This
is helpful for troubleshooting, and also to predict when the electrode may need to be replaced.
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