Model 106-L Ozone Monitor Manual Rev. E
26
4. CALIBRATION
Every analytical instrument is subject to some drift and variation in response,
making it necessary to periodically check the calibration. Dynamic calibration is
a multipoint check where gas samples of known concentrations are sampled by
the instrument in order to determine a calibration relationship. For more
information on calibration of ozone monitors refer to the Code of Federal
Regulations (Title 40, Part 50, Appendix D) and the EPA’s Technical
Assistance Document for the Calibration of Ambient Ozone Monitors.
Calibration is the process of adjusting the gain and offset of the Ozone Monitor
against some recognized standard. The reliability of the data collected from any
analytical instrument depends on the accuracy of the calibration, which is
largely dependent upon its analytical traceability to a reference material or
reference instrument calibration.
Because of the instability of ozone, the certification of ozone concentrations in a
compressed gas cylinder is impossible due to loss of ozone over time. When
ozone concentration standards are required, the ozone must be generated and
certified on site. The following are based on EPA requirements for calibrations
of ozone monitors for monitoring in compliance with the Clean Air Act. Similar
procedures are recommended for other applications as well.
Ozone standards can be classified into two basic types:
1. A
Primary Ozone Standard
is the combination of an ozone generator and
an ozone monitor based on UV absorbance (a UV photometer) that has
been setup in accordance with the procedures prescribed by the U.S.
Environmental Protection Agency (EPA) under Title 40 of the Code of
Federal Regulations, Part 50, Appendix D (40 CFR Part 50).
2. An
Ozone Transfer Standard
is a system (a portable ozone monitor and/or
a portable ozone generator), which can produce accurate ozone
concentration standards which are quantitatively related to a primary ozone
standard. An example of an ozone transfer standard is the 2B Technologies
Model 306 Ozone Calibration Source. Ozone transfer standards must be
certified before use in accordance with the procedures prescribed by the
U.S. Environmental Protection Agency (EPA) under Title 40 of the Code of
Federal Regulations, Part 50, Appendix D (40 CFR Part 50).
