Walchem WebMaster ONE Instruction Manual page 73

the sensor error alarm will activate. If both sensors are invalid, control stops and the sensor error
alarms activate.
To select this sensor as the backup sensor, click the Enable radio button, then click on the Submit
button at the bottom of the page. The page will reload showing the status of the sensor as Backup,
and offer additional menus:
Primary Sensor Assignment
This menu only appears if the Redundant Sensor Setting is Backup.
Use the pulldown arrow to select the sensor to use as the primary control sensor. All sensors of the
same type as the backup sensor will appear in the pulldown list.
Deviation from Primary Sensor
This menu only appears if the Redundant Sensor Setting is Backup.
Type the maximum allowable difference between the two sensor readings. If this deviation is
exceeded, then control of any outputs using the sensor will stop and an alarm activated.
Current Reading/Calibrate
The current reading is a live reading of the calibrated concentration of oxidizer in the sample.
To Calibrate the sensor click on the "Perform Calibration" button and a new window will appear.
Select a zero calibration or a 1-point process calibration by clicking the appropriate button.
Zero Calibration
A zero calibration must be performed on initial installation, or after cleaning or replacing the
membrane or electrolyte. This step must be done prior to the process calibration.
Remove the sensor from the flow cell and place it in a beaker of clean, oxidizer-free water.
Allow the sensor 15 minutes to equilibrate to the water temperature.
Click on the Zero Calibration button.
Step 1 will display the current mV reading from the sensor and direct you to place the sensor in
pure water. Stir the water with the sensor until the mV reading is stable for at least 5 minutes.
Click Continue when the mV reading is stable.
If the value is within the range of calibration, it will display "Zero Calibration was Successful".
Press the Enter key after replacing the sensor in the flow cell.
If not, it will display "Calibration Failed!" Refer to Section 8 for troubleshooting.
1 Point Process Calibration
Ensure that the sensor is conditioned and equilibrated to the temperature of the sample.
Ensure that the sample flow rate is between 30 and 100 liters/hour.
Perform a test on the sample water for the oxidizer concentration.
Enter the 1 point process calibration menu.
Step 1 will display the current ppm reading of the water using the previous calibration. When the
reading is stable, use the Arrow keys to fill in the new value, and then click on the Continue
button.
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