Sensor Menu - Walchem WDP420 Instruction Manual

5.2

Sensor Menu

The sensor menu provides the following settings: Calibration history (informational only), 2 point
calibration, 1 point calibration, pH/ORP selection, and other calibration menus. Each is discussed in
detail below. Refer to the Sensor Menu chart on the next page.
Note: If you are programming the unit for the first time, press the
Type" menu first to choose standard pH, antimony pH, or ORP. Then press
the "Use Buffer Rec" menu and choose whether you want to use automatic buffer recognition or not.
Then press ENTER
Cal'd
2 Pt Calibration
2 Pt Calibration for pH
electrodes, using Auto
Buffer Recognition
.
Displays the date of the last electrode calibration.
Press the ENTER key to perform a 2 point calibration of the electrode.
Note: 2 point calibration instructions are given in the following order:
pH electrodes, using Auto Buffer Recognition,
pH electrodes, not using Auto Buffer Recognition,
ORP electrodes (Auto Buffer Recognition not available)
If using manual temperature compensation, the first display will be:
Cal Temp °F/C 68
Use the arrow keys to enter the actual temperature of the buffer solutions. If using automatic
temperature compensation, this display will not appear. Press ENTER to continue.
Rinse Electrode
Remove the electrode from the process and rinse it off. Press ENTER to go to the next step.
First Buffer
This is a prompt to place the electrode in the first buffer. In a few seconds the controller will
automatically go to the next step.
1st Buffer 7.00
The top line will show the temperature and the mV output from the electrode.
The bottom line will read "1st Buffer" on the left hand side and either "??.??" or a pH value on the
right hand side. If it reads a pH value, that means that it has recognized the buffer solution. Once the
buffer value is recognized, it will stop flashing and the mV value will begin flashing. Once this has
stabilized, it will stop flashing and go on to the next step.
If it reads "??.??", that means it hasn't recognized the buffer solution because the mV output of the
electrode is too far away from a standard buffer solution's theoretical mV value. If it can't recognize
the buffer solution, the controller will beep and display "Unknown Buffer", and then display its best
guess. Press ENTER to accept that guess, or change the value to the correct one using the arrow keys.
If you press ENTER when it reads "??.??", the display will switch to "Buffer Override" and allow
you to manually enter the buffer value.
Rinse Electrode
Remove the electrode from the first buffer solution and rinse it off with water. Press ENTER to
continue.
Second Buffer
Place the electrode in the second buffer solution. The controller automatically advances.
2nd Buffer 4.00
The top line will display the temperature and mV readings, which will blink until they become stable.
The bottom line will say "2nd Buffer" on the left hand side, either display the pH of the buffer
solution or "??.??" on the right hand side and will go to the next step or display "Unknown Buffer" as
in 1st Buffer above.
Cal Successful/Cal Failed
If the electrode response is good, then the display will read "Cal Successful". If the mV output of the
electrode did not change enough between the two buffer solutions, it will read "Cal Failed". A failure
usually means that the electrode needs to be cleaned, or replaced. It will also display the % difference
from the theoretical slope. A failure occurs if the slope is more than 80% different than theoretical.
See Troubleshooting Section for "Probe Error" if calibration failed.
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key once, and set the "Sensor
three times to get to
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