Teledyne 4020 – Hydrocarbon analyzer (special version for automatic background gas switching) - Manual (Page 81)

Total Hydrocarbon Analyzer Operation
Teledyne Analytical Instruments 63
To access the offset function:
<▲▼> From the MAIN MENU, scroll to the ANALOG
ADJUST function using the UP/DOWN keys.
<Enter> Pressing activates the function and takes you to
the next screen.
<Enter> Use the key to move over to the Offset field.
<▲▼> Use the UP/DOWN keys to change each digits value.
<Enter> Use the key to accept a digit and move to the
next character position. The final enter will accept the
value and move the arrow to the function which allows
you to set the gain.
Use the same procedure to set the gain of the instrument. After the
last digit is entered, the final press will accept the gain value.
The value you enter for the offset to zero or gain will be
automatically added to the reading. Thus, if you entered -0.10 for zero
offset
, the display will show -0.10 for zero concentration.
During calibration, when the instrument enters the zero mode in
AUTO, the instrument will do the work of bringing the reading back to
zero plus the offset value that was entered. If you chose MANual zero
mode, then you must adjust the zero of the instrument to read zero plus
the value entered as offset.
4.7.2 Background Gas Selection
The 4020 Analyzer can be used to analyze sample gas in a
background of either O
2
or N
2
. This menu is used to:
 O2/N2: Inform the instrument which background gas is being
used. The analyzer will then store or apply the proper
calibration parameters depending on whether the instrument
is currently in a calibration or measurement mode. The state
of the AL-2 contact will reflect this selection.
Note: Separate zero and span calibrations must have been