Yokogawa In-Situ Gas Analyzer TDLS200 - Manual (Page 130)

9-5
IM 11Y01B01-01E-A 6th Edition :Feb 13, 2013-00
<9. TROUBLE SHOOTING>
1. Alignment Adjustment
a. Sometimes the original mechanical alignment of the analyzer may change due to mechanical/
thermal properties of the installation or perhaps the alignment nuts not being fully tightened
originally. In these situations the analyzer can simply be realigned.
b. Adjust the mechanical alignment using small adjustments of typically one quarter turn per nut at a
time and allowing for at least two measurement up-dates before making further adjustments.
c. Start by adjusting the laser launch unit in the vertical plane i.e. direct the launch unit up and then
down while observing transmission (or detector signal voltage). If no improvement is achieved then
ensure the alignment is set back to the best possible vertical position.
d. Then proceed with launch unit horizontal adjustment, again using quarter turns per nut and waiting
for 2 measurement up-dates before making the next adjustment. If no improvement is achieved
then ensure the alignment is set back to the best possible horizontal position.
e. Now adjust the laser detect unit in the vertical plane i.e. direct the detect unit up and then down
while observing transmission (or detector signal voltage). If no improvement is achieved then ensure
the alignment is set back to the best possible vertical position.
f. Then proceed with detect unit horizontal adjustment, again using quarter turns per nut and waiting
for 2 measurement up-dates before making the next adjustment. If no improvement is achieved
then ensure the alignment is set back to the best possible horizontal position.
g. Repeat steps b through d again to ensure maximum transmission level.
h. If transmission is still limited then the issue could be with associated with the actual mechanical
installation. It may be that the nozzles and/or flanges attached to the process are in fact out of
tolerance.
2. Quality of Clear Aperture through Process
Sometimes, the original clear aperture through the process can
become impaired/fouled/plugged (see image to left) by material
deposited from the process gas inside the nozzles. The deposits are
usually solid formations (crystalline formations from cooled vapors
created when the cool purge gas mixes with the hot process gas)
and/or very sticky/viscous/tar like substances that may have to be
mechanically removed.
a. After having optimized alignment per above, the launch and
detect units should be removed to facilitate an inspection of the
process nozzles
b. If the installation incorporates ‘Process Isolation Flanges’ (see
image and diagram below) then the analyzer and alignment
flanges can be removed and the nozzle insides can be inspected
without compromising the process seal.