Teledyne 3020T - Manual (Page 47)

Trace Oxygen Analyzer Operation 4
4-11 Teledyne Analytical Instruments
The beginning zero level is shown in the upper left corner of the dis-
play. As the zero reading settles, the screen displays and updates information
on
Slope (unless the Slope starts within the acceptable zero range and does
not need to settle further).
Then, and whenever Slope is less than 0.08 for at least 3 minutes,
instead of Slope you will see a countdown:
1 Left, 0 Left, and so fourth.
These are two steps in the zeroing process that the system must complete,
AFTER settling, before it can go back to ANALYZE.
#### PPM Zero
1 Left=### ppm/s
The zeroing process will automatically conclude when the output is
within the acceptable range for a good zero. Then the analyzer automatically
returns to the ANALYZE screen.
4.8.1.2 Manual Mode Zeroing
ENTER the ZERO function. The screen that appears allows you to
select between automatic or manual zero calibration. Use DOWN/UP to
toggle between
AUTO and MAN zero settling. Stop when MAN appears on
the display.
Zero: Settling: Man
<ENT> To Begin
ENTER to begin the zero calibration. After a few seconds the first of
five zeroing screens appears. The number in the upper left hand corner is the
first-stage zero offset. The microprocessor samples the output at a predeter-
mined rate. It calculates the differences between successive samplings and
displays the rate of change as
Slope= a value in parts per million per second
(ppm/s).
#### ppm Zero
Slope=#### ppm/s
NOTE:It takes several seconds for the true
Slope Slope Slope Slope Slope
value to display.
Wait about 10 seconds. Then, wait until Slope Slope Slope Slope Slope
is sufficiently
close to zero before using ENTER to finish zeroing.
Generally, you have a good zero when
Slope is less than 0.05 ppm/s
for about 30 seconds. When
Slope is close enough to zero, ENTER it. In a
few seconds, the screen will update.
Once zero settling completes, the information is stored in the
microprocessor, and the instrument automatically returns to the ANALYZE
screen.