The turbomolecular pump’s temperature cutoff protects the bearing and prolongs
its lifetime. If the laboratory temperature is significantly above 30
°
C (86
°
C), the
pump cutoff temperature could be reached, and if so reached, would result in the
pump being shutdown.
There must be a good flow of air around the system, and the air conditioning
must be capable of maintaining a constant temperature (within operational limits)
in the immediate vicinity of the system. Using demanding GC methods the
average steady-state heat load of the 4000 MS is 6000 BTUs.
Humidity
The relative humidity of the operating environment must be between 40 and
80%, with no condensation. Operating a 4000 MS at very low humidity will result
in the accumulation and discharge of static electricity; this will shorten the life of
electronic components. Operating the system at high humidity will produce
condensation and result in short circuits. High humidity will also block the filters
on cooling fans and accelerate wear of the heads in the diskette drives.
Varian recommends that your laboratory be equipped with a
temperature/humidity monitor. This will ensure that your laboratory is always in
conformance with temperature and humidity specifications.
Exhaust System
It is your responsibility to provide an adequate exhaust system. Much of what is
introduced into the mass spectrometer will eventually be exhausted from the
mechanical pump, along with the small amounts of oil vapor that these pumps
characteristically emit. Therefore, the pump outlets should be connected to a
fume exhaust system. Consult local regulations for the proper method of
exhausting the fumes from your system.
Gas Requirements
Helium - GC Carrier Gas
Minimum 99.998% ultra-high purity with less than 1.0 ppm each of water,
oxygen, and total hydrocarbons. One 257-ft
3
tank with Matheson regulator
#3104-580, or equivalent tank and regulator.
NOTE: The presence of >1 ppm oxygen or water in the carrier gas supply may
significantly affect the performance of the 4000 MS, and it may damage such
components as the capillary column, filaments, and multiplier. Varian
recommends that its customers verify that their gas suppliers use controlled
tanks; this will ensure that purity standards are maintained. If you purchase pure
gases in contaminated tanks, you may end up with a contaminated system
requiring costly and time consuming repair.
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