Agilent Technologies 8355 Sulfur User Manual page 27

WA RNING
SCD and NCD User Manual
Hydrogen is a commonly used GC carrier gas. Hydrogen is
potentially explosive and has other dangerous characteristics.
• Hydrogen is combustible over a wide range of
concentrations. At atmospheric pressure, hydrogen is
combustible at concentrations from 4 % to 74.2 % by volume.
• Hydrogen has the highest burning velocity of any gas.
• Hydrogen has a very low ignition energy.
• Hydrogen that is allowed to expand rapidly from high
pressure into the atmosphere can self-ignite due to an
electrostatic spark.
• Hydrogen burns with a nonluminous flame which can be
invisible under bright light.
Hydrogen shutdown
Hydrogen gas is used as a fuel for the SCD and NCD detectors.
When using the detector with an Agilent 7890B or 7890A+ GC,
the GC monitors any hydrogen gas streams. If a stream shuts
down because it is unable to reach its flow or pressure setpoint,
and if that stream is configured to use hydrogen, the GC
assumes that a leak has occurred and declares a hydrogen
safety shutdown.
If the GC goes into hydrogen safety shutdown, the effects for the
detector are:
• The detector heated zones are turned off.
• The detector hydrogen flows are shut off.
• The ozone generator is turned off.
• The vacuum pump remains on.
To recover from this state, fix the cause of the shutdown (tank
valve closed, serious leak, others). Turn the instrument and
detector off, then back on.
The GC cannot always detect leaks in detector gas streams. For
this reason, it is vital that column fittings should always be either
connected to a column, or have a cap or plug installed. The H
streams must be configured for hydrogen so that the GC is aware
of hydrogen use.
Safety and Regulatory Information
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