Vigilantplant TDLS8000, User Manual

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<9. Inspection and Maintenance>
9-1
IM 11Y01D01-01EN
9. Inspection and Maintenance
CAUTION
If you need to remove the TDLS8000 from the process flange for inspection or maintenance, be
sure to turn off the power beforehand.
Work performed by an unqualified engineer can cause injury or severe damage to instruments.
Not following the warnings in this manual can also cause injury or severe damage to instruments.
Make sure that maintenance is carried out by a qualified engineer. A qualified engineer is an
engineer who:
• Is knowledgeable about the safe handling of process analysis instruments (or general
automation technology) and has read and understood the content of this manual.
• Has received instructions on how to start and configure instruments and has read and
understood the content of this manual.
This chapter explains inspection and maintenance to retain the measurement performance of the
TDLS8000.
There are no operations that need to be performed regularly on the TDLS8000.
When the laser beam transmission decreases, clean the process window.
9.1 Maintaining the Laser Beam and
Transmission
Transmission is a value determined by the magnitude of laser power that reaches the photo
detector in the sensor control unit (SCU) after the laser beam emitted from the laser element
of the LU passes through the gas to be measured. Transmission is used to verify aging after
the optical axis is adjusted. As startup, adjust the optical axis correctly, perform transmission
calibration, and set the transmission value to 100%.
By checking the variation in the transmission after startup, you can determine the state of the
region that the laser beam travels through, the degree of optical axis misalignment between
the LU and SCU, and the states of the laser beam emitting and receiving components. This
information is important for maintenance and troubleshooting.
Generally, the transmission degrades due to the conditions shown below.
To maintain normal TDLS8000 operation, perform the required inspection and maintenance
to prevent the transmission from degrading. To maximize the TDLS8000 performance, it is
particularly important to optimally adjust the optical axis and keep the process window clean.
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Stained process window
If the process window is stained, the laser beam will be blocked causing the amount of laser
beam reaching the photo detector to decrease. Perform process window purge continuously to
prevent stains from adhering to the process window. See “3.4 Piping”.
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Particles (dust and the like) in the process
Particles in the process gas block the laser beam causing the amount of laser beam reaching
the photo detector to decrease. For measurement locations (applications) with high level of
particles in the process, take measures such as installing insertion tubes as described in “3.1.3
Attaching the TDLS8000 to the Process Flange” in addition to process window purging.
3rd Edition: Jun. 10, 2016-00