Teledyne 6200A - Sulfides analyzer - Manual (Page 57)

TAI Model 6200A SO
2
Analyzer Operator Manual, 02164, Rev. G
Ultraviolet light is focused through a narrow 214 nm bandpass filter into the reaction chamber. Here
it excites the SO
2
molecules, which give off their characteristic decay radiation. A second filter
allows only the decay radiation to fall on the PMT. The PMT transfers the light energy into the
electrical signal which is directly proportional to the light energy in the sample stream being
analyzed. The preamp board converts this signal into a voltage which is further conditioned by the
signal processing electronics.
The UV light source is measured by a UV detector. Software calculates the ratio of the PMT output
and the UV detector in order to compensate for variations in the UV light energy. Stray light is the
background light produced with zero ppb SO
2
. Once this background light is subtracted, the CPU
will convert this electrical signal into the SO
2
concentration which is directly proportional to the
number of SO
2
molecules.
4-2