Teledyne LXT-220 User Manual
Page 47
Dissolved Oxygen Controller
Operation
Teledyne Analytical Instruments
47
2DO
8.40 ppm
Cal
-173.8 mV/FS
Span calibration menu pH
3. Clean the electrode and insert the sensor into the desired buffer.
4. Press both horizontal CALIBRATE keys simultaneously to enter
the calibrate mode. Observe the diagnostic value on the bottom
line change from historical data to a real-time value and that the
term "CAL" has disappeared.
5. To change the buffer point, position the cursor under the desired
digit using the left-hand CALIBRATE key.
6. Increase or decrease the value by pressing the appropriate
vertical CALIBRATE key.
7. Wait for the real-time mV value to stabilize.
8. To save the calibration and exit the calibrate mode, press either
MENU SELECTION key.
A perfect electrode slope (efficiency) is typically greater than -150.
mV/FS. If the value falls below -100.0 mV/FS, the electrode should be
serviced or replaced.
3.4.2.3 T
WO
-P
OINT
B
UFFER
C
ALIBRATION
(S
PAN
)
When first installing an electrode, the second cal point
establishes the slope variations or efficiency. The span is typically done
in air which is the saturation point of the solution when in equilibrium.
Procedure:
1. Perform a one-point calibration as outlined in Section 3.4.2.2.
2. Press the appropriate MENU SELECTION key to reach the
Electrode Span Menu and locate the cursor under the "2" as
illustrated.