Installation manual

Operating in Chemical Ionization (CI) Mode 4
5975 Series MSD Operation Manual 125
Typical pressure readings
Use the G3397A Micro-Ion vacuum gauge. Note that the mass flow controller is
calibrated for methane and the vacuum gauge is calibrated for nitrogen, so
these measurements are not accurate, but are intended as a guide to typical
observed readings (Table 20). They were taken with the following set of
conditions. Note that these are typical PCI temperatures:
Familiarize yourself with the measurements on your system under operating
conditions and watch for changes that may indicate a vacuum or gas flow
problem. Measurements will vary by as much as 30% from one MSD and gauge
controller to the next.
Source temperature 250 °C
Quad temperature 150 °C
Interface temperature 280 °C
Helium carrier gas flow 1 mL/min
Table 20 Flow and pressure readings
Pressure (Torr)
Methane Ammonia
MFC
(%)
EI/PCI/NCI MSD
(Performance turbo pump)
EI/PCI/NCI MSD
(Performance turbo pump)
10 5.5
×10
–5
5.0 ×10
–5
15 8.0 ×10
–5
7.0 ×10
–5
20 1.0 ×10
–4
8.5 ×10
–5
25 1.2 ×10
–4
1.0 ×10
–4
30 1.5 ×1
–4
1.2 ×10
–4
35 2.0 ×10
–4
1.5 ×10
–4
40 2.5 ×10
–4
2.0 ×10
–4