INFICON Explorer Portable Gas Chromatograph - Manual (Page 177)

Explorer Operator Manual
175
When Explorer changes the PID sensitivity (gain), it must monitor and change the
offset. This occurs during the pump time. Explorer begins to adjust the offset at
about 8-10 seconds into the pump time. Typical setting for the pump time do not
allow sufficient time for baseline stabilization after the extreme changes in offset
that occur during gain switching.
If it is necessary to switch gains between runs, set the pump times to at least 20.
Use typical times of 10 to 15 seconds when no gain switching is required. See page
193 for details on setting the pump time.
Integration Method
General Information
The integrator extracts information from the detector signal. The integrator has been
designed to reduce or eliminate the user input required for good chromatographic
integration.
Chromatographic peaks are identified according to the following recognition
sequence based on the slope of the signal coming from the detector. The integrator
looks for each step to occur in sequence.
To detect a peak the integrator goes through the following steps:
1. The slope exceeds a threshold value for a certain time period.
When this occurs, the peak has started.
2. The slope goes negative for a time period.
This indicates the peak maximum has been detected.
3. At this point the height of the peak can be calculated.
If it is greater than the Minimum Height value in the Integration Method then
the sequence is continued, otherwise the peak is disregarded and the integrator
goes back to step 1.
4. The slope, now negative, rises above a threshold value for a certain time
period.
The end of the peak has been detected.