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Chapter 4
Calibration
This chapter describes the procedures for performing a standard zero/span
calibration.
The 42iQ 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
90 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.
The following describes procedures for performing a multipoint calibration
of the 42iQ. The information described here is considered adequate to
perform the calibration. However, if greater detail is desired, the user is
referred to the Code of Federal Regulations, Title 40, Part 50, Appendix F.
The calibration technique is based on the rapid gas phase reaction between
NO and O
which produces stoichiometric quantities of NO
in
3
2
accordance with the reaction:
Thermo Scientific
42iQ Instruction Manual 4-1
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