Teledyne 3000TA - General purpose trace oxygen analyzer - Manual (Page 45)

Trace Oxygen Analyzer Operation 4
4-13 Teledyne Analytical Instruments
#### PPM Zero
4 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 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
Δ∇ keys
to toggle between AUTO and MAN zero settling. Stop when MAN appears,
blinking, on the display.
Zero: Settling: Man
To Begin
Press 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 prede-
termined 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 value to display. Wait about
10 seconds. Then, wait until Slope is sufficiently close to zero before
pressing 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, press Enter . In a
few seconds, the screen will update.
Once span settling completes, the information is stored in the
microprocessor, and the instrument automatically returns to the Analyze
mode.
4.4.1.3 Cell Failure
Cell failure in the 3000TA is usually associated with inability to zero
the instrument down to a satisfactorily low ppm reading. When this occurs,
the 3000TA system alarm trips, and the LCD displays a failure message.
#.# ppm Anlz