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Chapter 4
Calibration
The Model 43i Trace Level-Enhanced requires initial and periodic
calibration according to the procedures described in this chapter. A quality
control plan that allows the frequency and number of calibration points to
be modified depending on calibration and zero/span check data should be
implemented. Such a quality control program is essential to ascertain the
accuracy and reliability of the air quality data collected. The data compiled
for such a program might include items such as dates of calibration,
atmospheric conditions, control settings and other pertinent data. For more
detailed quality assurance guidelines, see the Quality Assurance Handbook
for Air Pollution Measurement Systems, published by the U.S. EPA, Research
Triangle Park, NC, 27711.
There are a number of conditions which should be met prior to a
calibration or a zero/span check. First, the instrument should have at least
30 minutes to warm up and stabilize. Second, the range used during the
calibration or zero/span check should be the same as that used during
normal monitoring. Third, all operational adjustments to the instrument
should be completed prior to calibration. Fourth, all parts of the gas flow
system, such as sample lines, and particulate filters, which are used in
normal monitoring should also be used during calibration. Finally, it is
recommended that the recording devices and outputs used during normal
monitoring be calibrated prior to the instrument calibration and that they
be used during the calibration or the zero/span check.
Zero Gas
An SO
-free (< 0.5 ppb) air supply is required for the proper calibration
2
and checkout of the instrument. There are several methods that are
Generation
acceptable to generate this zero gas. For more information about generating
zero air, See Appendix E, "Standards for Trace Level-Enhanced Analyzers."
Commercial
Commercial heatless air dryers filled with a mixed bed of activated charcoal
and a 13X molecular sieve have been found effective in removing SO
from
Heatless Air Dryers
2
compressed air. The use of this type of zero gas system is recommended
when minimum maintenance is of prime importance. This system requires
a source of compressed air. Refer to the manufacturer's recommendations
for installation of such a system.
Thermo Fisher Scientific
Model 43i Trace Level-Enhanced Instruction Manual
4-1
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Troubleshooting
