Model 202 Ozone Monitor Manual Rev. J-4
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6.
CALIBRATION
6.1.
Introduction
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 concentration 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 Model 202 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.
6.2.
Ozone Standards
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. 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).
6.3.
Equipment Required
The equipment that is needed to carry out the calibration is commercially available, or
it can be assembled by the user. Calibration using a primary ozone standard involves
the generation of ozone concentrations that are simultaneously measured by a
