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4 Operation Model Ultra Trace 3000
4-16
Teledyne Analytical Instruments
Span Val: 008.00ppm
<ENT>Span <UP>Mod #
Press ∆ (<UP>) to permit modification (Mod #) of span value.
Use the arrow keys to enter the oxygen concentration of the span gas
you are using (999.99 is maximum value of span gas). The < > arrows
choose the digit, and the ∆∇ arrows choose the value of the digit.
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 a Slope on the screen. It takes several seconds
for the first Slope value to display. Slope indicates the rate of change of the
Span reading. It is a sensitive indicator of stability.
#### % Span
Slope=#### ppm/s
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 full scale of the range being calibrated, for a period of ten minutes it is
sufficiently stable.) Once
Enter
is pressed, the Span reading changes to the
correct value. The instrument then automatically enters the
Analyze
func-
tion.
4.4.3 Span Failure
The analyzer checks the output of the cell at the end of the span. If the
raw output of the cell is less than 0.5 uA/ppm O
2
, the span will not be
accepted. The analyzer will return to the previous calibration values, trigger
the System Alarm, and display in the VFD:
Span Failed!!
This message will be shown for five seconds and the instrument shall
return to the Analyze mode. In the upper right hand corner of the VFD
display “FCAL” will be shown. This message flag will help the operator
troubleshoot in case calibration was initiated remotely. To reset the alarm
and the flag message, the analyzer must be properly spanned.
A trace cell is unlikely to fail span. As explained before, when the
sensor reaches the end of its useful life, the zero offset begins to rise until the
analyzer finds the zero unsatisfactory. Nevertheless, feeding the wrong span