Installation manual

Operating in Chemical Ionization (CI) Mode 4
5975 Series MSD Operation Manual 103
To pump down the CI MSD
You can also use the Local Control Panel to perform this task. See “Operating
the MSD from the LCP” .
Procedure
1 Follow the instructions for the EI MSD. See “To pump down the MSD” .
After the software prompts you to turn on the interface heater and GC
oven, perform the following steps.
2 Check the vacuum gauge, if present, to verify that the pressure is
decreasing.
3 Press Shutoff Valve to close the gas supply and shutoff valves.
4 Verify that PCICH4.U is loaded and accept the temperature setpoints.
Always start up and verify system performance in PCI mode before
switching to NCI.
5 Set the GC/MSD interface to 280 °C.
6 Set Gas A to 20%.
7 Let the system bake out and purge for at least 2 hours. If you will be
running NCI, best sensitivity, bake out the MSD overnight.