Analyzer Timing
| Appendix C-1
ANALYZER TIMING
Timing States / Periods
The Model 888 uses a state machine of 14 states to control the operation of
the analyzer. These fourteen states are referred to as “periods” in the user
manual. Timers are responsible for many of the events that cause state
transitions. The use of the term “period” is a carryover from the legacy
880NSL nomenclature.
Of the 14 states or periods, Periods 1 through 8 are common to all versions
of the Model 888. Periods 9 through 11 apply only to analyzers with the
steam blowback option. Periods 12 through 14 are special periods used for
diagnostic purposes. Figure 1-8 is a summary of the 14 periods.
The timers associated with many of the periods can be modified using
the Configure_Timers_Period Timer menu found in Chapter 4. All time
entries are in seconds.
Period 1 – Special Flush
This is the initial period when power is applied to the Model 888. This
period automatically transitions to Period 2 once the software finishes its
initialization process.
Period 2 – Flush and Zero
The analyzer remains in Period 2 until the sample system has reached
temperature and all system level alarms have cleared. During this time
the sample cell is continuously flushed with instrument air to prevent any
sulfur mist from the process solidifying and blocking flow in the oven.
Once all system alarms have been cleared, the Period 2 time will begin
counting down.
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