Installation and Start-Up | 3-35
Warming Stage
The Warming Stage begins immediately after the Cooling Stage ends.
The new HCDP temperature – obtained during the Cooling Stage – is
displayed on the User Interface. During this stage, the power applied to
the Thermoelectric Cooler is reduced stepwise to zero to allow the mirror
temperature to increase at a controlled rate of approximately 10 °C/minute
(18 °F/minute). The heat sources for warming the mirror are the Measur-
ing Cell, the contained sample gas, and the Heatsink.
If the determined value exceeds its associated alarm setpoint, or the Status
Code (SCode) indicates malfunction of the analyzer (by means of a Fault
or Warning alarm), the appropriate system relay is activated and its cor-
responding LED on the User Interface is turned On. If the alarm is a Fault
alarm, the alphanumeric display on the User Interface will also flash. The
SCode is determined by the built-in diagnostics function.
The Warming Stage continues until either:
• The mirror temperature reaches a temperature (a user-specified value,
typically 10 °C/18 °F) above the HCDP temperature detected during
the previous Cooling Stage,
or
• The mirror temperature is 5 °C (9 °F) below its High setpoint,
or
• If, after 2 minutes the mirror temperature has not increased.
At this point the Warming Stage ends and a new measuring cycle begins,
starting with the Purging/Hold Stage.
However, if the Warming Stage terminates because the mirror tempera-
ture has not increased after 2 minutes, the Stage-Time-Out (“w TimeOut”)
SCode and Warning-Stage-Time-Out (“w Warm TimeOut”) XSCode are
generated.
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