Thermal Conductivity Analyzer Part I: Control Unit
Part I 4-13
Teledyne Analytical Instruments
The beginning zero level is shown in the upper left corner of the display. As
the zero reading settles, the screen displays and updates information on Slope=
in percent/second (unless the Slope starts within the acceptable zero range and
does not need to settle further). The system first does a course zero, shown in
the lower right corner of the screen as
CZero
, for 3 min, and then does a fine
zero, and displays
FZero
, for 3 min.
Then, and whenever Slope is less than 0.01 for at least 3 min, instead of
Slope you will see a countdown: 9 Left, 8 Left, and so fourth. These are
software steps in the zeroing process that the system must complete, AFTER
settling, before it can go back to
Analyze
. Software zero is indicated by S
Zero in the lower right corner.
####.## % H2 N2
4 Left=#.### SZero
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
mode.
4.4.1.2 Manual Mode Zeroing
Press
Zero
to enter the
Zero
function. The screen that appears allows you
to select between automatic or manual zero calibration. Use the ∆∇ keys to
toggle between AUTO and MAN zero settling. Stop when MANUAL appears,
blinking, on the display.
Select zero
mode: MANUAL
Press
Enter
to begin the zero calibration. After a few seconds the first of
three 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.
####.## % H2 N2
Zero adj:2048 CZero
The analyzer goes through C–Zero, F–Zero, and S–Zero. During C–Zero
and F–Zero, use the ∆∆
∆∆
∆∇ keys to adjust displayed Zero adj: value as close as
possible to zero. Then, press
Enter
.
S–Zero starts. During S–Zero, the Microcontroller takes control as in Auto
Mode Zeroing, above. It calculates the differences between successive sam-
plings and displays the rate of change as Slope= a value in parts per million per
second (ppm/s).