Teledyne LXT-280 - Manual (Page 32)

Calibration LXT-280
Teledyne Analytical Instruments 22
4. Magnetically activate the RIGHT HORIZONTAL ► arrow
key 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 HORIZONTAL◄ arrow key.
6. Increase or decrease the value by magnetically activating the
appropriate VERTICAL ▲/▼ arrow key.
7. Wait for the real-time mV value to stabilize.
8. To save the calibration and exit the calibrate mode, magnetically
activate the LEFT HORIZONTAL◄ arrow key until the cursor
is all the way to the left and the term “Cal” on the second line
reappears.
Perform a span calibration after the zero calibration.
4.5 Span Calibration
The span calibration is typically the only calibration that needs to
be performed on a routine basis. This calibration compensates for
changes in the membrane or deterioration of the electrolyte. Teledyne
recommends the span calibration be performed in air or in an oxygen
standard that is near the range in which the process normally operates.
These two span calibrations are described in the SP-1/SP-2 Sensor
Installation and Maintenance Manual.
The following procedure describes the steps used to calibrate the
LXT-280 to the sensor. If performing an air span calibration where the
unit of measurement is ppm, review Section 5.0, Calibration Correction
Factors. This instrument calibration procedure can also be used to
calibrate to a sample that has been analyzed through a wet chemical
process, such as a Winkler analysis.
Procedure:
1. Perform a zero calibration as outlined in Section 4.4.
1 DO 0
0.2 mV