Yokogawa In-Situ Gas Analyzer TDLS200 - Manual (Page 97)

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IM 11Y01B01-01E-A 6th Edition :Feb 13, 2013-00
<7. ROUTINE MAINTENANCE>
The TDLS200 TDL analyzer requires little routine maintenance if it has been installed, set-up and calibrated
correctly. This section will outline the routine maintenance procedures.
7.1 Maintaining Good Transmission
The % Transmission of the laser light through the process is the most important variable to consider for routine
maintenance and troubleshooting. Under normal operating conditions (nonfailure) transmission will be affected
by:
• Alignment of the Launch and Detect units (covered below)
• Window fouling. For most applications where solids or liquids are expected in the process a window
purge is recommended (see installation section)
• Particulate in the process. Particulate in the process will block the laser light to some extent. To
maximize performance in particulate laden processes it is important to maximize alignment and ensure
windows are clean.
7.1.1 Maintaining Clean Windows
If the window purge supplies have been set-up correctly on a reliable supply line, then under normal operating
conditions there should be no window fouling. Window fouling may be caused by one or more conditions:
• Loss of window purge gas flow/pressure which then allows the dirty process gas to contact the windows
and leave deposits.
• Loss of window purge gas flow/pressure which then allows the hot process gas to contact the window,
condense any liquids and leave deposits.
• Over pressure of the process gas which allows the process gas to overcome the window purge gas and
contaminate the window.
• Contact on the window by an incompatible gas (such as HF on the standard BK-7 Borosilicate crown
glass).
• Contamination of the purge gas supply, either by particulate matter, oil or other.
If the windows are contaminated they may be cleaned using the following procedure:
• Remove analyzer from process (isolate, etc. if necessary).
• Use a clean, dry instrument air or nitrogen pressure supply to first blow off any particulate matter.
• Using warm water and mild soap detergent, gently clean the window surface with a soft, non-abrasive
cloth.
• If the deposits do not come off then use a small amount of IPA (Isopropyl Alcohol) and a soft,
non-abrasive cloth.
• Use the same clean, dry instrument air or nitrogen pressure supply to blow dry the surface.
• Carefully check the entire surface of the window from different angles to ensure it is thoroughly cleaned
and ready for service.
• If the window does not appear to clean up well, then replace the window assembly with a new one.
• If the window appears to have an etched surface then it has probably been contaminated with HF or
other similar corrosive gas.
7 ROUTINE MAINTENANCE