4 Operation Model 3000PA
4-12 Teledyne Analytical Instruments
of the displayed value of the oxygen concentration (in ppm) for three min-
utes. Then the instrument automatically returns to the analyze mode.
4.4.2.2 Manual Mode Spanning
Press
Span
to start the
Span
function. The screen that appears allows
you to select whether the span calibration is to be performed automatically or
manually.
Span: Settling:MAN
<ENT> For Next
Use the ∆∇ keys to toggle between AUTO and MAN span settling.
Stop when MAN appears, blinking, on the display. Press
Enter
to move to
the next screen.
Span Val: 20.90
<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 (20.90 if you are using air). The < > arrows chose 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 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.
#### % 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 five 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.
4.5 The
AlarmsFunction
The Model 3000PA is equipped with 2 fully adjustable concentration
alarms and a system failure alarm. Each alarm has a relay with a set of form