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Calibration 5
•
Using the MODE button, navigate to the CALIBRATE?
submenu and while holding in the button, press the DOWN
button to initiate a zero calibration.
•
After the CAL DELAY period the instrument will go into
calibration mode and the display will read "DOING ZERO
CAL". Calibration data will be collected for 20 seconds.
•
After the 20 second calibration, if a manual span calibration is
to follow, switch valve A to sample gas and valve B to SPAN.
Otherwise, switch valve A to sample gas and leave valve B in
the position shown in the inset. This will allow the sample gas
to flow.
At this stage, the composition of the gas in the sample cell is
pure zero gas. Purge the cell by allowing span or sample gas to
flow for a sufficient time.
NOTE:
If the TRACK/HOLD function has been set to HOLD (see section 4.3),
then there will be no change in the screen display and the output will
remain fixed on the last reading taken before entering the calibration.
At the end of the 20-second calibration there will be another delay
equal to the time delay set in CAL DELAY. This delay is used to allow
sample gas to purge the sample cell of zero gas before the instrument
resumes monitoring. It is important to close the zero gas valve and
open the sample gas valve during this delay to ensure sufficient
purging has occurred before monitoring is resumed.
If a problem is encountered during calibration and the instrument
cannot calibrate, the data from the last successful calibration will be
restored, if possible. A series of messages will be displayed on the screen
informing the user why the calibration failed and if the old values have
been restored. See Section 6 Maintenance.
CAUTION: This analyzer will zero calibrate to almost any gas. It will even
zero calibrate to your sample or span gas! If the wrong gas is
used for zero calibration, it is almost certain that the instrument
will fail in span calibration and/or generate unusable data. Make
absolutely certain that zero gas is flowing in the cell during the
zero calibration by double checking the valve status and
watching the flow meter on the front panel.
5.3.2 Manual Span Calibration
CAUTION: It is important to use a valid SPAN gas for calibration. The
concentration of the span gas must be greater than 50% of the
full range of the instrument, preferably 80%.
48
Teledyne Analytical Instruments., - Rev. 3
IR7000
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