Teledyne 9110EH - Nitrogen Oxides Analyzer - Manual (Page 106)

Operating Instructions Model 9110EH Instruction Manual
6.10.1.3. iDAS Triggering Events
Triggering events define when and how the iDAS records a measurement of any given data
channel. Triggering events are firmware-specific and are listed in Appendix A-5. The most
common triggering events are:
• ATIMER: Sampling at regular intervals specified by an automatic timer. Most
trending information is usually stored at such regular intervals, which can be
instantaneous or averaged.
• EXITZR, EXITSP, SLPCHG (exit zero, exit span, slope change): Sampling at the end
of (irregularly occurring) calibrations or when the response slope changes. These
triggering events create instantaneous data points for the new slope and offset (con-
centration response) values at the end of a calibration. Zero and slope values can be
used to monitor response drift and to document when the instrument was calibrated.
• WARNINGS: Some data may be useful when stored if one of several warning
messages appears. This is helpful for trouble-shooting by monitoring when a
particular warning occurred.
6.10.2. Configuring the iDAS
6.10.2.1. Default M9110EH iDAS Configuration
A set of default data channels has been included in the analyzer’s software for logging
nitrogen oxides concentrations, calibration and predictive diagnostic data. These default
channels are listed in Table 0-22 and are defined as follows:
CONC: Hourly averages of NO
X
, NO and NO
2
concentrations and the NO
X
stability (standard
deviation). These data are recorded at one minute intervals and stored every full hour with
a time and date stamp. Readings during calibration and the calibration hold off period are
not included in the averages. By default, the last 800 hourly averages are stored, which
covers more than one month of continuous data acquisition. This channel also logs the
number of (1-minute) samples within each average for statistical evaluation of the
concentration means.
CALDAT: Logs concentration, slope and offset values for NO
X
and NO every time a zero or
span calibration is performed (triggering event: SLPCHG). The NO
X
stability (to evaluate if
the calibration value was stable) as well as the converter efficiency (for trend reference) are
also stored. This data channel will store data from the last 200 calibrations and can be used
to document analyzer calibration and detect trends in slope and offset (instrument
response). As with all data channels, a date and time stamp is recorded for every logged
data point.
CALCHECK: This channel logs concentrations and the stability each time a zero or span
check (not calibration) is finished (triggered by exiting any calibration menu). The data of
this channel enable the user to track the quality of zero and span responses over time and
assist in evaluating the quality of zero and span gases and the analyzer’s noise specifica-
tions. The STABIL figure documents if the analyzer response was stable at the point of the
calibration check reading. The last 200 data points are retained.
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