Controller / User Interface | 4-45
Calibration gas must be injected into the analyzer at a relatively low flow
rate (1–2 L/min or 0.04–0.07 SCFM). The routing of the calibration gas tub-
ing provides warming of the calibration gas but the system will not allow
excessive flow rates of calibration gas to be warmed. At low flow rates,
there is always the possibility of calibration gas becoming contaminated
with remnants of the sample gas, which will introduce errors into the
calibration results.
To overcome this problem, Zero gas is introduced along the same path-
way that the calibration gas follows. If the Zero gas does not show signs of
contamination at lower flow rates, it is safe to introduce calibration gas.
To perform a Manual Span:
1. Zero the analyzer to remove sample gas contaminants. Note and re-
cord the numeric value displayed for Flow Control. Run the Manual
Zero for 10 minutes at a flow rate of 2.5 L/min (0.08 SCFM).
Reduce the Zero flow rate to 1.5 L/min (0.05 SCFM). Check for a
change in concentration reading. There should be very little change
in baseline. If there is a significant change continue with the 2.5 L/min
(0.08 SCFM) flow rate for another 10 minutes.
When the analyzer is in Continuous Backpurge/Zero Flow mode
there may be air pressure at the Calibration Gas Port. Do not open the
Calibration Gas Port when the analyzer is in this mode.
2. Ensure that the Calibration Gas mixture containing component
‘y’ (y = 1, SO
2
or y = 2, H
2
S) is connected to the analyzer’s Calibration
Gas Port (Figure 4-7) and turned on.
Turn off the Aspirator Air.
Adjust the Calibration Gas Regulator to obtain a pressure similar to
that on the analyzer Aspirator Pressure Gauge.
3. Press F5 0 and record the numeric value displayed for FlowCtrl.
Change the Flow Control setting to Continuous Sample mode. This
will allow the flow of Calibration Gas to manually span the sample
system.
!
WARNING
(FlowCtrl) CALF5 0
Del 2 Ent Ent
See “Manually Zeroing
the Analyzer” in Chapter 3.
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