Siemens ULTRAMAT 23 Series Equipment Manual page 160

Functions
8.5 Automatically executed functions of the H2S sensors
The function test is set during execution of the purging function in order to signal that the
displayed value is incorrect.
How the purging function works
The purging function is triggered if the continuous measured value of H
permissible continuous concentration (12.5 vpm) in measuring mode for a period equal to the
duration of the zero gas purge time.
Following triggering of the purging function:
• The last measured values of all components are 'frozen' if the 'Analog outputs with FCTRL'
parameter has been set to 'Hold', or the current measured values are still displayed for all
other settings.
• A "V" (H
right edge where the test letter "!" appears (fault logged, no longer pending).
• The zero gas valve is opened.
• The "Function control" status is set.
As long as the purging function is active, the zero gas valve remains open during the zero gas
purge time. The device then switches to the sample gas path. The status 'Function control
(FCTRL)' remains set and the test letter "V" flashes during the zero gas purge time and the
subsequent pre-purging phase. This signals that the displayed measured values are incorrect.
The status 'Function control' and the test letter are deleted following the pre-purging phase, and
the current measured values displayed again. Monitoring of the H
permissible continuous concentration is already re-activated during the pre-purging phase.
Return to measuring mode
An active purging function can be exited or interrupted if:
• The H
continuous concentration during the pre-purging phase
• The probe protection function is triggered
• A different device status is started such as calibration, AUTOCAL, etc.
Sequence parameter
The zero gas purge time is twice the AUTOCAL purge time. The pre-purging phase is equal to the
AUTOCAL purge time. The AUTOCAL purge time is an adjustable parameter whose setting is
described in section Calibration: AUTOCAL/drift values: Purge time (Page 126).
The device remains in measuring mode while the protection function is running. You can read
out via ELAN or PROFIBUS whether the protection function of the analyzer is being processed,
and in which step.
The following illustration shows how the purging function runs over time:
160
S purging function running) is displayed flashing in the measurement screen at the
2
S measured value remains permanently below the threshold for the permissible
2
S is greater than the
2
S threshold for the
2
Equipment Manual, 04/2022, A5E37100388-012
ULTRAMAT 23