Walchem WebMaster ONE Instruction Manual page 63

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/Perform Calibration
The current reading is a live reading of the calibrated conductivity of the sample.
To Calibrate the conductivity, click on the "Perform Calibration" button and a new window will
open in your browser. You will have two options, a one-point process calibration or an air (zero)
calibration.
Always set the air calibration first. This should only need to be done once for any given sensor.
Click the Calibrate button. Make sure that the sensor is in the air and dry, then click the Continue
button. The controller will either accept the calibration or will reject it if the voltage reading is too
far from the expected for a zero reading. Click the Close button to return to the Conductivity Input
page.
For the one-point process calibration, click its Calibrate button. It will display the current
conductivity reading. Determine the actual conductivity of the solution by measuring it with a
calibrated conductivity instrument, and type this value in the text box, then click the Continue
button. The controller will either accept the calibration or will reject it if the conductivity entered
is too far from the factory calibration reading. The limit is  50% of the uncalibrated reading.
Click the Close button to return to the Conductivity Input page.
Status
This section is for information only, and lets you know if any alarm conditions exist. Possible
status messages are; Normal (everything is OK), Sensor Error (the sensor signal is not valid), High
Alarm, Low Alarm or Calibration Time. For Sensors 2, 3 and 4 an error message for Circuit
Board Failure is also possible. 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 conductivity input. Click on the "Self Test"
button, and the controller will display either Pass or Fail, and also readings of a simulated
conductivity and temperature. If the controller passes self test, and you are having problems
reading the correct conductivity, then the problem must be with the sensor, wiring or installation.
ppm Conversion Factor (only appears if ppm selected as the unit of measure)
Type the value that you want to use to convert S/cm to ppm into the text box. The range allowed
is 0.5 to 1.0 ppm per S/cm.
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