Theory Of Operation; Measurement Principle; So Ultraviolet Fluorescence - Teledyne 100E Instruction Manual

Model 100E Instruction Manual

10. THEORY OF OPERATION

The M100E UV Fluorescence SO
determines the concentration of sulfur dioxide (SO
instrument. It requires that sample and calibration gases be supplied at ambient
atmospheric pressure in order to establish a constant gas flow through the sample
chamber where the sample gas is exposed to ultraviolet light causing the SO
excited (SO *). As these SO
2
measures the amount of fluorescence to determine the amount of SO
sample gas.
Calibration of the instrument is performed in software and usually does not require
physical adjustments to the instrument. During calibration, the microprocessor measures
the sensor output signal when gases with known amounts of SO
concentrations are supplied and stores these measurements in memory. The
microprocessor uses these calibration values along with other performance parameters
such as the PMT dark offset, UV lamp ratio and the amount of stray light present and
measurements of the temperature and pressure of the sample gas to compute the final
SO concentration.
2
This concentration value and the original information from which it was calculated are
stored in the unit's internal data acquisition system and reported to the user through a
vacuum fluorescent display or as electronic data via several communication ports.
This concentration value and the original information from which it was calculated are
stored in the unit's internal data acquisition system (iDAS Section 6.10) and reported to
the user through a vacuum fluorescent display or several communication ports.

10.1. Measurement Principle

10.1.1. SO
Ultraviolet Fluorescence
2
The physical principle of the M100E's measurement method is the fluorescence that
occurs when sulfur dioxide (SO
range of 190 nm - 230 nm. This reaction is a two-step process.
The first stage (Equation 10-1) occurs when SO
photons of the appropriate wavelength (190 nm - 230 nm). The SO
energy that causes one of the electrons of the SO
orbital state. In the case of the Model 100E, a band pass filter between the source of the
UV light and the affected gas limits the wavelength of the UV light to approximately 214
nm.
045150102 Rev XB1
Analyzer is a microprocessor controlled analyzer that
2
* molecules decay into SO
2
) is excited by ultraviolet light with wavelengths in the
2
SO + hv 
2 214 nm
), in a sample gas drawn through the
2
they fluoresce. The instrument
2
at various
2
molecules are struck by ultraviolet
2
molecule to move to a higher energy
2
Ia
 →  SO 2 *
Theory Of Operation
become
2
present in the
2
retains some excess
2
(Equation 10-1)
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