Ametek 241CE II User Manual page 81

Sub-Menu Item Description
RunType End-of-Run Type setpoint temperature (°C or °F) at which the Cooling Stage will terminate.
The parameters that can be displayed include:
• LowT = Low Temperature
• HCDP = Hydrocarbon Dewpoint Temperature
Regardless of the selection, the Cooling Stage will be terminated if the mirror temperature
reaches the LowT setpoint, or the analyzer is unable to achieve a lower temperature within a
2-minute period.
Cycle Fixed Time Cycle allows you to specify a fixed cycle interval (minutes) for the Hydrocarbon
Dewpoint (HCDP) temperature measurement. This option must only be used in conjunction
with the End-of-Run Type for Hydrocarbon Dewpoint found.
Note:
To disable the function and use the analyzer's default cycle settings, enter '0' while viewing
this parameter.
To enable this function, enter a positive value (minimum '8') while viewing this parameter. If
a positive value of less than '8' is entered, the system will default to '8' minutes (the fixed time
cycle will begin at the start of the next cycle).
When the Fixed Time Cycle option is enabled, the mirror is cooled from the Mirror Start
temperature at a Fast Rate of 15 °C/minute until 2 °C above the last determined HCDP
temperature, or 2 °C above the lowest temperature attained if no HCDP is detected. At this
point, the mirror is cooled at a Slow Rate of 2 °C/minute until the HCDP is detected. Upon
exiting the Cooling Stage and entering the Warming Stage, the mirror is warmed at a rate of
15 °C/minute. As the mirror warms to 2 °C above the last determined HCDP temperature or
the lowest temperature attained if no HCDP is detected, the Cell Purging Stage begins.
The duration of the Purging Stage is the time remaining until the next Cooling Stage is
scheduled to begin using the fixed cycle time specified. Since the purge duration is variable,
the Purging/Hold-Stage-Time-Out warning (w Hold Timeout) may be raised frequently if the
temperature differential between the mirror start temperature and the HCDP temperature
is substantial enough that the mirror does not have sufficient time to reach the Mirror Start
temperature, or the analyzer is unable to stabilize the mirror to the Mirror Start temperature.
The one exception to the fixed interval dewpoint determination cycle is the first cycle upon
power up. Since the dewpoint temperature is unknown upon power up, the analyzer will
determine the dewpoint temperature in the first cycle: Purge the Cell for the time specified,
cool the mirror at the Slow Rate specified, determine the HCDP temperature, warm the
Mirror to the start temperature, purge the Cell for the time specified, and stabilize the mirror
temperature at the Start Temperature. The fixed cycle interval cycle applies when the next
cooling stage begins.
Note:
PN 903-8797, Rev A
The Fixed Cycle Time parameter is also available using the optional Modbus
communication (Register 1072); however, this parameter is not accessible using
System 200 Configurator Software communication. If your system uses the
optional Modbus communication function, refer to the 241CE II Analyzer Serial
Communication Interface (Modbus) Manual Supplement shipped with your
system.
See "About the Measuring Cycle" in Chapter 2 for more information about
measuring cycle times and when to adjust the cycle duration.
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User Interface 3-15