TELEDYNE API Everywhereyoulook 480H, Руководство пользователя

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09421A DCN8343 Teledyne API Model 480H O
3
Monitor User Manual 55
As can be seen, the concentration of ozone depends on more than the intensity ratio.
Temperature and pressure influence the density of the sample. The density of the
gas changes the number of ozone molecules in the absorption cell which impacts the
amount of light removed from the light beam. These effects are addressed by
directly measuring temperature and pressure and including their actual values in the
calculation. The absorption coefficient is a number that reflects the inherent ability
of ozone to absorb 254 nm light. Most current measurements place this value at 308
cm-1 atm-1 at STP. The value of this number reflects the fact that ozone is a very
efficient absorber of UV radiation which is why stratospheric ozone protects the life
forms lower in the atmosphere from the harmful effects from solar UV radiation.
Lastly, the absorption path length determines how many molecules are present in
the column of gas in the absorption cell.
The intensity of light is converted into a voltage by the detector/preamp module.
The voltage is converted into a number by a high resolution A/D (analog-to-digital)
converter. The digitized signal, along with the other variables, is used by the CPU to
compute the concentration using the above formula.