Installation manual

Operating in Chemical Ionization (CI) Mode 4
5975 Series MSD Operation Manual 107
The flow control module
The CI reagent gas flow control module (Figure 28 and Table 17) regulates the
flow of reagent gas into the CI GC/MSD interface. The flow module consists of
a mass flow controller (MFC), gas select valves, CI calibration valve, shutoff
valve, control electronics, and plumbing.
The back panel provides Swagelok inlet fittings for methane (CH4) and one
OTHER reagent gas. The software refers to them as Gas A and Gas B,
respectively. If you are not using a second reagent gas, cap the OTHER fitting to
prevent accidental admission of air to the analyzer. Supply reagent gases at
25 to 30 psi (170 to 205 kPa).
The shutoff valve prevents contamination of the flow control module by
atmosphere while the MSD is vented or by PFTBA during EI operation. The
MSD monitors will reflect On as 1 and Off as 0 (see Table 17).
Figure 28 Reagent gas flow control module schematic
Gas A
(methane)
supply
Gas B
(other)
supply
Gas A
select valve
Gas B
select valve
Mass
flow
controller
Calibration
valve
Restrictor
Calibration
vial
Shutoff
valve
GC/MSD
interface
GC column
CI ion
source