Thermo Scientific 49i, Instruction Manual, Page: 137 / 314

Thermo Fisher Scientific Model 49
i
Instruction Manual 4-1
Chapter 4
Calibration
This chapter describes how to perform a multipoint calibration of the
photometric ozone analyzer. It is based upon the current EPA approved
procedure using a UV photometer as a calibration standard. The
information described here should be adequate to perform the calibration.
However, for more information 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.”
This chapter includes the following sections:
• “Equipment Required” on page 4-1
• “Instrument Preparation” on page 4-3
• “Calibration Photometer System Preparation” on page 4-3
• “Calibration Procedure” on page 4-8
• “Periodic Zero and Span Checks” on page 4-11
• “Internal Ozonator Adjustment (Option)” on page 4-13
Equipment Required
The following equipment is required to calibrate the analyzer:
• Zero air generator
• Calibration photometer system
Zero Air Generator
Zero air can be obtained either from compressed cylinders or from scrubbed
ambient air. If cylinder air is used, it should be actual and not synthetic. If
ambient air is used, the following compounds must be removed: ozone,
nitric oxide, nitrogen dioxide, sulfur dioxide, and hydrocarbons. The
following scheme is recommended by the EPA in its technical assistance
document: