Principles Of Operation; Sulfur Dioxide; So Ultraviolet Fluorescence Measurement Principle; Sensor Principles Of Operation - Teledyne t100 Operation Manual

12.

PRINCIPLES OF OPERATION

12.1. SULFUR DIOXIDE (SO
OPERATION
12.1.1. SO ULTRAVIOLET FLUORESCENCE MEASUREMENT PRINCIPLE
2
06807F DCN7335
This section describes the principles of operation for the T100 SO
12.1), for the optional O
12.3). It also describes the principles of operation for pneumatics (Section 12.4),
electronics (Section 12.5), communication interfaces (Section 12.6) and software
(Section 12.7).
) SENSOR PRINCIPLES OF
2
The T100 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; this exposure causes the
SO molecules to change to an excited state (SO
2
SO they fluoresce. The instrument measures the amount of fluorescence to determine
2
the amount of SO present in the sample gas.
2
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 (refer to Section7) and reported to
the user through a vacuum fluorescent display or several communication ports.
The physical principle upon which the T100's measurement method is based is the
fluorescence that occurs when sulfur dioxide (SO
ultraviolet light with wavelengths in the range of 190 nm-230 nm. This reaction is a two-
step process.
sensor (Section 12.2) and for the optional CO
2
Analyzer is a microprocessor controlled analyzer that
2
2
analyzer (Section
2
2
), in a sample gas drawn through the
2
*). As these SO * molecules decay into
2
) is changed to excited state (SO
2
sensor (Section
at various
2
*) by
2
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