Vigilantplant TDLS8000, User Manual

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<9. Inspection and Maintenance>
9-26
IM 11Y01D01-01EN
Insufficient nitrogen gas concentration may affect the measurement gas concentration
readings.
• The region where the laser beam passes through is adequately filled with nitrogen gas.
If measured gas is mixed, measurement gas concentration readings will be affected.
• There is no optical noise in the region where the laser beam passes through.
Proper zero calibration cannot be performed in a condition where optical noise is present
(for example, if the surface of the process window is clouded). This can affect measurement
gas concentration readings.
• There is no electrical noise in the environment where zero calibration is to be performed.
Proper zero calibration cannot be performed in a condition where electrical noise is present.
This can affect measurement gas concentration readings.
NOTE
• If the purge piping leaks, correct results cannot be obtained.
• Wait at least 1 hour after turning on the power before performing calibration.
9.5.1 Preparation
Follow the instructions in “9.3 Mounting on a Calibration Cell”. The piping method is describe
below.
l
Zero+span calibration gas
A piping arrangement that allows span calibration gas to be used in addition to zero calibration
gas. Zero calibration and span calibration can be executed.
Laser unit (LU)
Flow cell
Sensor control unit (SCU)
Purge gas Purge gas
Process gas
(Stream1)
Zero
(Stream2)
Span
(Stream3)
Valve-2
(SV-2)
Valve-1
(SV-1)
In this arrangement, automatic zero and span calibration can be executed consecutively.
There are two methods to start a consecutive execution. One is by using YH8000, Modbus, or
digital input (semi-automatic execution), and the other is to start at a specified time (automatic
execution). Semi-automatic execution is not possible from HART. For details on automatic and
semi-automatic execution, see “9.8 Automatic and Semi-automatic Execution of Validation
and Calibration”.
For details on consecutive execution, see “9.8.5 Consecutive Automatic Execution”.
3rd Edition: Jun. 10, 2016-00