Teledyne 4020 – Hydrocarbon analyzer (special version for automatic background gas switching) - Manual (Page 77)

Total Hydrocarbon Analyzer Operation
Teledyne Analytical Instruments 59
▲▼>
Use the <▲▼> keys to toggle between the options of:
“ALWAYS SAMPV” (sample valve)
“ALWAYS SPAN” (span valve)
“ALWAYS ZERO” (zero valve)
<Enter> Press when the appropriate valve selection is
displayed on screen.
<Escape> Use Escape to move back to the Analyze Mode. Note that
the analyzer will now switch gas to the analyzer from the
selected port regardless of whether the analyzer is in
analyze or calibration mode.
As an example of the display in Analyze mode when USER SELECT
is the current valve selection mode and “Always SAMPLE” valve is
chosen, the display will be as follows:
or when in SPAN mode:
4.6.16.3 D EFAULT (B Y F UNCTION )
In the default mode of valve selection, the specific valve that is open
to the analyzer depends on whether the analyzer is in Analysis mode or
is in a calibration mode. If it is in Analysis mode, the “SAMPLE” valve
is open to the analyzer. If it is in a calibration mode then either the
“SPAN” or ZERO” valve will be open to the analyzer.