Vigilantplant TDLS8000, User Manual

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<9. Inspection and Maintenance>
9-6
IM 11Y01D01-01EN
9.2 Online Validation
Online validation is performed by purging a validation cell with check gas of known concentration
while measuring the concentration of the measured gas under stable measured gas
concentration conditions. The conditions that are controlled (or known) when purging with check
gas are as follows.
• Pressure of the purge check gas
• Temperature of the purge check gas
• Length of the validation cell purged with check gas
• Concentration of the purge check gas
The basic procedure is shown below.
• Set known validation parameters.
• Purge the validation cell with check gas of known concentration.
=> The result of “Process concentration” + “additional concentration from the check gas” is
recorded in the TDLS8000.
• Purge the validation cell again with the original purge gas (typically nitrogen gas).
=> “Process concentration” is recorded in the TDLS8000.
=> The expected value for the “additional concentration from the check gas” is calculated
from the known parameters.
=> The expected value and the actual value are compared and validated (pass or fail).
NOTE
Perform online validation when the process is stable. Validation cannot be performed accurately
when the concentration, temperature, or pressure of the process gas is fluctuating greatly.
NOTE
Validation is a procedure to check whether the TDLS8000 is operating properly. If there is a
reading error as a result of validation, check that there are no gas leaks from the process. If there
is no gas leak, perform calibration.
9.2.1 Preparation
In online validation, a validation cell is purged with check gas. There are two check gas piping
methods.
• When there is no process gas switching
Up to two check gases are connected for online validation 1 and online validation 2 (Figure
9.4).
• When there is process gas switching
A single check gas is connected for online validation 2. The remaining stream is used to
switch between two process gases (Figure 9.5).
NOTE
If you want to switch the check gas stream through automatic valve control using the TDLS8000
SV terminal, you need to set the TDLS8000 valve usage according to the piping method as
shown in the following table. For details on valve usage, see “6.8.2 Valve Usage Setting”.
3rd Edition: Jun. 10, 2016-00