Teledyne 4020 – Hydrocarbon analyzer (special version for automatic background gas switching) - Manual (Page 66)

Operation Model 4020
Teledyne Analytical Instruments 48
sample system, you may have to flow calibration gas for
several minutes to purge the gas line of sample gas.
<Enter> With the arrow adjacent to Zero (Span) as shown above,
press to activate the sub function.
<▲▼> Use the UP/DOWN keys to increment or decrement the
concentration value until the known value of your
zero(span) gas concentration is displayed.
<Enter> Press to accept this value.
<▼> Press the DOWN key once to move the arrow down one
line to the text Zero (Span) Begin.
<Enter> Press to start the calibration.
The 4020 will begin to analyze the concentration of the zero (span)
calibration gas and LED display above the VFD will change to reflect
the calibration gas concentration as the analysis proceeds. Internally, the
microprocessor calculates the difference between successive samplings
and displays the concentration as it changes. In MANUAL mode, the
operator can terminate the calibration at any point by scrolling to Finish
and pressing . Wait until the concentrations as shown on the
screen stabilizes before ending the calibration After terminating the
calibration the zero (span) value will be stored in the microprocessor’s
memory and you can continue with additional calibration or escape to
Analyze Mode.
Auto Zero
If you selected Auto for the zero calibration, The microprocessor will
determine the appropriate termination point for the zero or span
calibration based on the rate of change of concentration with time as the