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Model 400E Ozone Analyzer
Instruction Manual
EPA Protocol Calibration
P/N 04316 Rev: B
189
To maintain a uniform and consistent set of references, the US EPA maintains 9
Standard Reference Photometers (SRP) around the US. It is suggested that the
regional office of the EPA be contacted for the location of a SRP nearby and that the
standards be compared. This assures a uniform standard for ozone concentration is
applied everywhere.
Currently, the U.S. SRP Network consists of SRP’s located at:
1.
EPA's National Exposure Research Laboratory (NERL), in Research Triangle Park,
North Carolina
2.
EPA's Region I Environmental Services Division in Lexington, Massachusetts
3.
EPA's Region II Environmental Services Division in Edison, New Jersey
4.
EPA's Region IV Environmental Services Division in Athens, Georgia
5.
EPA's Region V Environmental Services Division in Chicago, Illinois
6.
EPA's Region VI Environmental Services Division in Houston, Texas
7.
EPA's Region VII Environmental Services Division in Athens, Georgia
8.
EPA's Region VIII Environmental Services Division in Denver, Colorado
9.
The State of California Air Resources Board (CARB) in Sacramento, California
Commercial UV photometers meeting the requirements of a primary ozone standard
as set forth in 40 CFR Part 50 are available and are currently being used by air
monitoring agencies. Agencies have been encouraged to compare their primary O
3
standards (and O
3
transfer standards) as part of their routine quality assurance
(QA) programs.
Additionally, to provide a reference against which calibration standards for O
3
must
be compared, the U.S. EPA has prescribed a reference calibration procedure based
on the principle of UV light absorption by ozone at a wavelength of 254 nm.
1
This
procedure provides an authoritative standard for all O
3
measurement. Ozone
transfer standards may also be used for calibration if they have been certified
against the UV calibration procedure.
3
8.1.5.
Calibration Frequency
A system of Level 1 and Level 2 zero/span checks is recommended (see
Section 8.2). These checks must be conducted in accordance with the specific
guidance given in Subsection 9.1 of Section 2.0.9 (Ref. 11). Level 1 zero and span
checks should be conducted at least every two weeks. Level 2 checks should be
conducted in between the Level 1 checks at a frequency determined by the user.
Span concentrations for both levels should be between 70 and 90% of the
measurement range.