Teledyne 7120 - NDIR analyzer - Manual (Page 53)

4 Operation Model 7120
4-20 Teledyne Analytical Instruments
ENTER will move the blinking field to units (%/ppm). Use UP/DOWN key
to select the units, as necessary. When you have set the concentration of the
span gas you are using, Enter to begin the Span calibration.
####.##% CO2
Slope=#.### Span
The beginning span value is shown in the upper left corner of the display.
As the span reading settles, the screen displays and updates information on
Slope. Spanning automatically ends when the span output corresponds, within
tolerance, to the value of the span gas concentration. Then the instrument auto-
matically returns to the analyze mode.
4.4.2.2 Manual Mode Spanning
Scroll Span by using UP/DOWN key and Enter to start the Span function.
The screen that appears allows you to select whether the span calibration is to
be performed automatically or manually.
Select span
mode: MANUAL
Use the UP/DOWN key to toggle between AUTO and MAN span setting.
Stop when MAN appears, blinking, on the display. ENTER to move to next
subfunction screen
Span Val: 2Ш.ШШ %
To begin span
Using the UP/DOWN key changes the span value, as necessary. Enter to
move to the units field (%/ppm). Use UP/DOWN key to select unit.
Press Enter to enter the span value into the system and begin the span
calibration.
Once the span has begun, the microprocessor samples the output at a
predetermined rate. It calculates the difference between successive samplings
and displays this difference as Slope on the screen. It takes several seconds for
the first Slope value to display. Slope indicates rate of change of the Span
reading. It is a sensitive indicator of stability.
####.##% CO2
Slope=#.### Span
When the Span value displayed on the screen is sufficiently stable, press
Enter . (Generally, when the Span reading changes by 1 % or less of the range
being calibrated for a period of ten minutes it is sufficiently stable.) Once Enter