Internal UV Ozone Photometer Page 9-
the tube determines the ozone concentration according to the
following equation:
Equation 9-1
Where:
= Absorption Coefficient of ozone at 254nm and with
the sample gas at 0°C and 760 mmHg = 308
L = Optical Path Length = 31.6 cm
I = Sample Count
(Conditioned detector output for sample gas)
I
o
= Reference Count
(Conditioned detector output for clean air)
T = Sample Temperature (°C)
P = Sample Pressure (mmHg)
Note that the temperature “T” and pressure “P” are included in
Equation 9-1. The on-board microcontroller measures the
temperature and pressure of the sample gas in order to perform
the automatic temperature/pressure correction of the ozone
reading.
Ozone PPB
T
P L
I
I
o
( ) ln
273
273
760
10
9
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