Walchem WebMaster ONE Instruction Manual page 43

Temperature Calibration
The current temperature reading will be displayed. Measure the actual temperature of the system
water and use the Arrow keys to enter this value. Press the Enter key to highlight 'CONTINUE',
then press Enter again to put the new value into memory.
If the calibration factor is within +/- 15 degrees C (27 degrees F) the display will be "Cal
Successful", otherwise it will be "Cal Fail".
pH Calibration
There are three calibration options that will be displayed. Use the Next key to move the cursor to
the word "Calibrate" beneath the option that you want to use, then press the Enter key to start the
calibration.
Most commonly used is the "2 pt Buffer Cal" where two pH standard solutions are used to
calibrate the electrode. This is the most accurate, since the slope of the electrode (mV output per
pH unit) is measured directly.
The "1pt Buffer Cal" is not as accurate, since it assumes that the slope of the electrode is 59
mV/pH unit, which will only be true with a new electrode. This can be OK if the pH never varies
far from the value of the standard solution used in the calibration.
The third is a "1 pt Process Cal", where the pH electrode is left in the process solution, and the pH
value is entered to match that of a hand held pH meter, or litmus paper. It also assumes a perfect
slope.
2 pt Buffer Cal
Step 1 will explain that control is suspended during the calibration procedure. Press the Enter key
when the cursor is on "Continue" to start the calibration. To cancel the calibration, press the Next
key to move the cursor to "Cancel", then press the Enter key.
Step 2 will ask you to enter the temperature of the buffer solutions. Use the Arrow keys to change
the value of the temperature, then press the Enter key to highlight 'CONTINUE', then press Enter
again to put the value into memory.
Step 3 will prompt you to rinse the electrode, and place it into the first buffer solution. Press the
Enter key to continue.
Step 4 will ask you to enter the value of the first buffer solution. Use the Arrow keys to change the
value, then press the Enter key to highlight 'CONTINUE', then press Enter again to put the value
into memory.
Step 5 will display the mV output of the electrode in the first buffer. When this reading is stable,
press the Enter key to continue.
Step 6 will prompt you to rinse the electrode and place it in the second buffer. Press the Enter key
to continue.
Step 7 will ask you to enter the value of the second buffer. Use the Arrow keys to change the
value, then press the Enter key to highlight 'CONTINUE', then press Enter again to put the value
into memory.
Step 8 will display the mV output of the pH electrode in the second buffer. When the reading is
stable, press the Enter key to continue.
39