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Ozon (O3)

½-times målinger

Resultaterne benyttes til smog varsling.

Målemetode

Ozon (O3) måles ved absorption af ultraviolet stråling. Luften suges ind i et kammer og belyses med ultraviolet lys. O3 absorberer effektivt lys af en bestemt bølgelængde i det ultraviolette område. Koncentrationen af O3 kan derfor bestemmes udfra hvor meget af det ultraviolette lys, der absorberes i kammeret.

Teknisk beskrivelse (engelsk)

Analyzing method: UV-absorption.

O3 monitors (API M400 and 400A):

  • Principle: UV-absorption at 254 nm. The ratio between the absorption in the measurement cell with sample air and with absorption in the cell with O3 selectively removed permit calculation of the O3 concentration.
  • Measuring range: 0-500 ppb, at 0.6-0.8 l/min.
  • Lower detection limit: <1 ppb
  • Precision ±5%
  • Selectivity: Water vapour dilute the sample
  • Routine checks: Automatic zero point check every day around midnight with zero- air from a generator, and "span" check by a built-in O3-generator.
  • Calibration at the laboratory: 1) O3 from a generator traceable to NIST. Checked against a NIST reference photometer once a year.