GE MOA 280i, Руководство по эксплуатации и обслуживанию

Страница: 64 / 211

GE Analytical Instruments ©2006 DLM 14291 Rev. A
6-4
FIGURE 7-1: Setup for Gas Calibratio
n
Zero Gas Calibration Warnings
If a stable zero gas calibration in
either low or high sensitivity
cannot be obtained, an unstable
calibration warning is displayed.
This situation can occur if the zero
air sample was not sampled for 5
minutes before starting the
calibration, if the caps are not
removed from the zero air filter
(no flow into NOA) or if the flow
rate of the zero air cylinder is <
200 mL/min and room air is being
drawn into the detector.
If the ppb offset is more than 100
counts or the ppm offset is more
than 5 counts, the display will
change to indicate that the zero
calibration exceeded the
recommended limits. This usually
indicates that the gas being used
for the zero calibration contains > 1 ppb NO or there is a light leak or other cause
of the high background. When the offsets are out of range, a warning message will
be displayed. Press ENTER to view the out of range offsets values (values may be
rejected from the Accept Menu) or press CLEAR to return to the Calibration Menu.
In general, do not accept out of range calibrations. Chapter 14 lists procedures to
be followed to determine the cause of the high background.
If the offsets are OK, pressing the ENTER button from the Accept Menu will store
the new calibration values in the battery-backed RAM.
NO Calibration Gas
The second step in the calibration is to determine the response of the NOA for a
known concentration of nitric oxide. The preferred method is to use a gas