16
Installing GC columns
Before you can operate your GC/MSD system, you must select, condition,
and install a GC column. This chapter will show you how to install and
condition a column. For correct column and flow selection, you must know
what type of vacuum system your MSD has. The serial number tag on the
lower front of the left side panel shows the model number.
Many types of GC columns can be used with the MSD but there are
some restrictions
During tuning or data acquisition the rate of column flow into the MSD
should not exceed 2.0 milliliters per minute for the diffusion pump MSD,
or 4.0 milliliters per minute for the turbomolecular pump MSD. Therefore,
there are limits to column length and flow.
• Narrow-bore columns (0.20 mm id or 0.25 mm id) can be installed
directly into the GC/MSD interface. Do not exceed recommended column
flow.
• Wide-bore columns (0.32 mm id), and megabore columns (0.53 mm id)
at least 100 meters long, can be installed directly into the GC/MSD
interface of the turbo pump MSD. Flow restrictions apply. Wide-bore and
megabore columns cannot be used with the diffusion pump MSD.
This information is summarized in Table 1. The dimensions listed are nomi-
nal values. The velocities and flows listed are calculated values at 70°C.
Actual values can vary from column to column and vary greatly with oven
temperature, unless the electronic pneumatic control (EPC) on the GC is
set for constant flow. See To measure column flow linear velocity
(page 46) for instructions on how to measure actual flow in your column.
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HP G1098A Diffusion pump Foreline pressure
HP G1099A Turbo pump Turbo speed
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