I
NITIAL
S
TARTUP AND
C
ALIBRATION
748250-L Rosemount Analytical October 1999
3-19
Model 880A Non-Dispersive Infrared Analyzer
Note:
When entering this function for viewing purposes only (by pressing the ZERO or
SPAN key), press SHIFT/ENTER to exit.
To calibrate the analyzer with the Calibration Gas Control.
1. Allow system to warm up a minimum of two hours.
2. Connect the solenoid valve for the zero gas to the two form C contacts. Connect
the zero gas to the sample cell inlet located on the back of the analyzer. The gas
should flow at a rate of 500 cc/min, as read on a flowmeter, until the display
reading stabilizes.
3. To calibrate the zero setting for the analyzer, press ZERO. To calibrate the span
setting for the analyzer, press SPAN. Wait for the reading to stabilize, and then
press ENTER.
3.14 AUTO ZERO/SPAN
Refer to Figure 3-14. The Auto Zero/Span allows automatic, unattended calibration at
set intervals. The option has six contact closures, four of which are field
programmable for frequency and duration of the calibration cycle (span 1, span 2,
span 3 and zero). Meanwhile, the other two contact closures indicate insufficient zero
and span adjustments and also drift limits for zero and span, if activated.
The auto zero/span [AUTO-CAL: ON] display allows the user to select ON or OFF to
turn the Auto Zero/Span “on” or “off”. Toggling from OFF to ON resets the timers for
the Auto Zero/Span. To reset the timers when the Auto Zero/Span is “on”, toggle from
ON to OFF to ON.
The sample and hold [SH: YES] display allows the user to select YES or NO to turn
the automatic sample and hold “on” or “off”. When the sample and hold feature is “on”,
the recorder and Current Output do not get updated until the calibration sequence is
completed.
The range selection [RANGE: 1Y 2Y 3Y] display allows the user to select the ranges
which will be automatically calibrated with span gas by using the
→
arrow to move the
cursor to the desired range and using the
↑
or
↓
key to select Y (yes) or N (no) for
each range. The zero for all three ranges will be calibrated at each interval regardless
of range(s) selected.
The initial delay [DELAY nnn HR] display allows the user to select the amount of time
until the first automatic calibration occurs. This is the initial delay until the automatic
cycle starts. At this time a zero and span calibration is made regardless of selection. If
a zero delay is selected there will be an automatic two minute delay.
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