Standard Practices for Calibration of Ozone Monitors Using Transfer Standards

Importancia y uso:

5.1 The reactivity and instability of O₃ precludes the storage of O₃ concentration standards for any practical length of time, and precludes direct certification of O₃ concentrations as SRMs. Moreover, there is no available SRM that can be readily and directly adapted to the generation of O₃ standards analogous to permeation devices and standard gas cylinders for sulfur dioxide and nitrogen oxides. Dynamic generation of O₃ concentrations is relatively easy with a source of ultraviolet (UV) radiation. However, accurately certifying an O₃ concentration as a primary standard requires assay of the concentration by a comprehensively specified analytical procedure, which must be performed every time a standard is needed.

5.2 The primary UV standard photometers, which are usually used at a fixed location under controlled conditions, are used to certify transfer standards that are then transported to the field sites where the ambient ozone monitors are being used. See Practice D5110.

5.3 The advantages of this procedure are:

5.3.1 All O₃ monitors in a given network or region may be traced to a single primary standard.

5.3.2 The primary standard is used at only one location, under controlled conditions.

5.3.3 Transfer standards are more rugged and more easily portable than primary standards.

5.3.4 Transfer standards may be used to intercompare various primary standards.

Subcomité:

D22.03.02

Referida por:

D1356-20A, D1356-20A, D7439-21, D1356-20A, D5110-22A, D5149-24, D5156-22, D8406-22

Volúmen:

11.07

Número ICS:

13.040.01 (Air quality in general)

Palabras clave:

boric acid titration; gas phase titration; ozone; primary standard; transfer standard;