The 6400A So Analyzer; Principle Of Operation - Teledyne 6400A Instruction Manual

TAI Model 6400A SO
4 THE 6400A SO

4.1 Principle of Operation

The operation of the TAI Model 6400A Analyzer is based upon the well proven technology from the
measurement of fluorescence of SO
190 nm - 230 nm region free of quenching by air and relatively free of other interferences.
Interferences caused by PNA (poly-nuclear aromatics) are reduced by a "kicker"
PNA selectively through a membrane without affecting SO
The UV lamp emits ultraviolet radiation which passes through a 214 nm bandpass filter, excites the
SO molecules, producing fluorescence which is measured by a PMT with a second UV bandpass
2
filter. The equations describing the above reactions are as follows:
+ ⎯ ⎯→
Ia
SO hv
2 1
The excitation ultraviolet light at any point in the system is given by:
[
= −
Ia I 1 exp
0
Where I is the UV light intensity, a is the absorption coefficient of SO
0
the concentration of SO
fluorescence:
⎯ ⎯→
KF
SO *
2
When the SO
2
background is air, the above expression reduces to:
( )
F =
K SO (4)
2
Hence, the fluorescent radiation impinging upon the PMT is directly proportional to the
concentration of SO
The block diagram in Figure 4-1 illustrates the general operation principle of the Model 6400A.
1
Developed by Dr. Henk, J. Vande Wiel, Laboratory for Inorganic Chemistry, RIVM, National
Institute of Public Health and Environmental Protection, Biethoven, The Netherlands.
Analyzer Operator Manual, 02164, Rev. G
2
ANALYZER
2
2
SO 2 * (1)
]
( ( ) )
−
ax SO (2)
2
. The excited SO
2
+
SO hv (3)
2 2
concentration is relatively low, the path length of exciting light is short and the
.
2
due to absorption of UV energy. Sulfur Dioxide absorbs in the
2
decays back to the ground state emitting a characteristic
2
4-1
1
which removes
sample gas.
, x the path length, and (SO
2
)
2