Yokogawa Extractive Oxygen Gas Analyzer TDLS220 - Manual (Page 54)

<7 ROUTINE MAINTENANCE> 7-1
IM 11Y01B02-01E-A 4th Edition September 11, 2012-00
7 Routine Maintenance
The TDLS220 TDL analyzer requires little routine maintenance if it has been correctly installed, set-up and
calibrated. This section will outline the routine maintenance procedures. Maintenance procedures require
opening enclosures of certain modules. Make sure that there is no ingress of water or other liquids into the
analyzer modules during these procedures.
7.1 Maintaining Good Transmission
The % Transmission of the laser light through the process gas flow cell is the most important variable to
consider for routine maintenance and troubleshooting. Under normal operating conditions (non-failure)
transmission will be affected by:
• Window/Mirror fouling. For most applications TDLS220 extractive the sample gas should
be pre-conditioned and clean thus avoiding any window fouling issues.
o It is VERY IMPORTANT to keep the process gas clean and non-condensing.
Deposits, oily films and other residues depositing on the window/mirror may cause
performance degradation/cyclical drift.
• Alignment of the Laser Beam - not necessary for TDLS220 as it is pre-fixed at factory
• Particulate in the process. For most applications TDLS220 extractive the sample gas
should be pre-filtered and clean thus avoiding any window fouling issues.
7.1.1 Maintaining Window and Mirror:
The incoming process gas should be pre-conditioned to remove any entrained liquids. The sample
gas should always be maintained above the dew point to prevent condensation within the flow cell. It is
recommended that a coalescing membrane type filter be installed up-stream of the flow cell inlet. Should
transmission become lower and/or the results become noisy/un-expected then it is possible the process
wetted optical surfaces need cleaning or replacement. Use the following procedures to check the Mirror and
Window. Locations are as shown below: