Teledyne LXT-280 - Manual (Page 35)

Dissolved Oxygen Transmitter Calibration
Teledyne Analytical Instruments 25
4.8 Back-to-Factory Calibration
This feature allows the LXT-280 to be reset to "nominal electrode"
situation. This condition is an electrode with zero millivolts offset at
zero percent or ppm oxygen, and a full scale output of –400 mV. This
factory calibration feature is very useful in providing a reliable starting
point if the instrument has been mis-calibrated.
CAUTION: IDEAL INSTRUMENTATION CALIBRATION DOES
NOT IMPLY IDEAL SYSTEM CALIBRATION.
Before using the factory calibration feature, it must be understood
that it provides a nominal instrument calibration and does not allow for
electrode variations or shortened span of the electrode in service. In
order to obtain ideal system calibration, a span calibration is required.
The following procedure for returning the LXT-280 back-to-factory
calibration can be used for both zero and span calibrations.
This procedure is required at BOTH of the calibration points.
Procedure at the Zero Menu:
6. Magnetically activate the appropriate VERTICAL ▲/▼ arrow
key to reach the Electrode Zero Menu.
7. Position the cursor under the “C” in “Cal.”
8. Magnetically activate the RIGHT HORIZONTAL ►arrow key
and observe the cursor briefly move to the right and the mV
value change to 0.00. The default setting is complete.
9. Verify the calibration by observing a .0 calibration point at .0
mV.
Procedure at the Span Menu:
1. Magnetically activate the appropriate VERTICAL ▲/▼ arrow
key to reach the Electrode Span Menu.
2. Position the cursor under the “C” in “Cal.”
2 DO .0
Cal -400.0 mV