Varian 450-GC, Руководство пользователя

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Installation Installation
Page: Page: 8 8 User User Manual Manual 450-GC 450-GC Varian, Varian, Inc. Inc.
Hydrogen as Carrier Gas Hydrogen as Carrier Gas
The use of hydrogen as a GC carrier gas is potentially dangerous. The use of hydrogen as a GC carrier gas is potentially dangerous.
Hydrogen (H Hydrogen (H
2 2
) is ) is a commonly used GC carrier gas. Hydrogen, however, is a commonly used GC carrier gas. Hydrogen, however, is
potentially explosive and has other characteristics that potentially explosive and has other characteristics that make it make it dangero dangerous. us.
••
Hydrogen Hydrogen is co is combustible mbustible over over a w a wide ide range range of of concentration concentrations. At s. At
atmospheric pressure, hydrogen is combustible at concentrations from atmospheric pressure, hydrogen is combustible at concentrations from
4% to 74.2% by volume.
4% to 74.2% by volume.
••
Hydrogen Hydrogen has has the the highest highest burning burning velocity of velocity of any any gas. gas.
••
Hydrogen Hydrogen has has very very low low ignition ignition energy. energy.
••
Hydrogen Hydrogen temperature temperature increases increases as as the the gas gas expands. expands.
••
Hydrogen Hydrogen that that is allo is allowed wed to e to expand xpand rapidly rapidly from h from high igh pressure pressure can can self self
ignites. ignites.
••
Hydrogen burns Hydrogen burns with a with a no no luminous flame luminous flame which can which can be be invisible under invisible under
bright light. bright light.
Hydrogen is potentially explosive. Take extreme care when using Hydrogen is potentially explosive. Take extreme care when using
hydr
hydr ogen as the GC ca ogen as the GC carrier gas i rrier gas i n a GC n a GC sys sys tem. tem.
All users should All users should be aware of th be aware of the mechanism e mechanisms by which hydroge s by which hydrogen can n can
accumulate accumulate. They should also know what . They should also know what precaution precautions to s to take if they know, take if they know, or or
suspect, that hydrogen has accumulated. suspect, that hydrogen has accumulated.
Mechanism Results Mechanism Results
GC off GC off
A GC can be shut dow A GC can be shut down deliberately. It can also be shut dow n deliberately. It can also be shut down accidentally by an n accidentally by an
internal or external failure. internal or external failure.
If a GC equipped with Electronic Flow Control (EFC) is shut off, the EFC does stop the
If a GC equipped with Electronic Flow Control (EFC) is shut off, the EFC does stop the
flow of carrier gas.
flow of carrier gas.
Power Power failure failure If If the the power power fails, fails, the the GC GC shuts shuts down. down. The The carrier carrier gas gas is is shut shut down down (in (in case case of of EFC). EFC).
Table 1: Hydrogen as Carrier Gas during Power off Table 1: Hydrogen as Carrier Gas during Power off