4
Operating in EI Mode
96
5975/5977 Series MSD Operating Manual
Venting the MSD
A program in the data system guides you through the venting process. It turns
off the GC and MSD heaters and diffusion pump heater or the turbo pump at the
correct time. It also lets you monitor temperatures in the MSD and indicates
when to vent the MSD.
The MSD
will
be damaged by incorrect venting. A diffusion pump will
backstream vaporized pump fluid onto the analyzer if the MSD is vented before
the diffusion pump has fully cooled. A turbo pump will be damaged if it is vented
while spinning at more than 50% of its normal operating speed.
WARNING
Make sure the GC/MSD interface and the analyzer zones are cool (below
100 °C) before you vent the MSD. A temperature of 100 °C is hot enough to
burn skin; always wear cloth gloves when handling analyzer parts.
WARNING
If you are using hydrogen as a carrier gas, the carrier gas flow must be off
before turning off the MSD power. If the foreline pump is off, hydrogen will
accumulate in the MSD and an explosion may occur. Read
on page 19 before operating the MSD with hydrogen carrier gas.
CAUTION
Never vent the MSD by allowing air in through either end of the foreline hose.
Use the vent valve or remove the column nut and column.
Do not vent while the turbo pump is still spinning at more than 50%.
Do not exceed the maximum recommended total gas flow. See
