Transfer Standards For Calibration of Air Monitoring Analyzers for ...

Ozone Transfer Standard Guidance Document 10/2013
Other procedures are not necessarily precluded, but due concern for accuracy should be exercised. In
designing or selecting a transfer standard, preference should be given to transfer standard configurations that allow
direct comparison with the photometer, as described in the procedure below. Thus, a transfer standard should have an
air supply capable of providing sufficient zero air for the photometer reference cycle without adversely affecting the
generated O 3 atmospheres.
Procedure 1: Assay by Ultraviolet –
The UV procedure for obtaining primary O 3 standards (described in Section 2 and Appendix A) is basically
an analytical technique using a UV photometer. The photometer (reference standard) can be used to assay the output
concentration of a generation-type transfer standard. To do this, the photometer must be disconnected from its own O 3
generation and output system and connected to the transfer standard output (see Figure 3.2). Care must be exercised to
disturb the UV photometer as little as possible from its normal configuration, and to ensure that the output flow of the
transfer standard exceeds the flow demand of the UV photometer.
A significant problem arises with this procedure, however. In order to accurately measure I O for the
transmittance (I/ I O ) measurement, the UV photometer must be able to sample zero air from the same source as that
used for the generation of the O 3 concentrations (see Appendix A). If the zero air supply of the transfer standard is
capable of providing sufficient additional zero air for the photometer, it may be tapped and connected to the two-way
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