Sampling Mode - Agilent Technologies 8860 User Manual

5 Maintenance and Troubleshooting

Sampling mode

Sampling mode
This mode is a pretreatment and is used for low concentration samples or
permanent gases. This mode unblocks the entire gas pipeline (for the bag version
the pump will also turn on in this mode), so the sample gas can purge any
remaining gas from the entire flow path.
When very low-concentration samples or permanent gases such as oxygen and
nitrogen are analyzed, the gas remaining in the selector system pipeline may affect
the sample results, especially when multiple gas bags are connected. For the
sample bag at the back of the injection sequence, a long wait time will cause the
small amount of gas remaining in the pipeline to continuously diffuse into the gas
bag, causing contamination of the sample. This mode helps minimize
this pollution.
Selector
MPV
Multi-Position Valve
1
On/Off Valve n/Off Va V V lv
Gas
Bag
Figure 19 Sampling mode for bag version.
70
Purge Valve
Needle Valve 1
Needle Valve 2
Pump
Assembly
Agilent Gas Sample Selector for 8860 and 8890 User Manual
Sample Loop
Carrier Gas
Selector GC
Purge N
2
GC Selector
Vent
Sample Gas
Purge Gas
Carrier Gas
GC Valve 1
To Column
4
5 3
6 2
Sample Out
1
Sample In
• GC Valve 1 – OFF
• Sample Valve – ON
• Purge Valve – OFF
• Pump – ON