Teledyne 2000A-EU - General purpose thermal conductivity analyzer - Manual (Page 51)

Thermal Conductivity Analyzer Operation 4
4-13 Teledyne Analytical Instruments
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.
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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.
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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).
Note: It takes several seconds for the true Slope value to display.
Wait about 10 seconds. Then, wait until Slope is sufficiently
close to zero before pressing
Enter to finish zeroing.
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Slope=##### C—Zero