Taylor-Wharton Bulk Tank Safety Data - Manual (Page 6)

6
Keep air and other gases away from liquid hydrogen. The low tem-
perature of liquid hydrogen can solidify any gas except helium. Solidified
gases and liquids allowed to form and collect can plug pressure-relief
passages and foul relief valves. Plugged passages are hazardous because
of the continual need to relieve excess pressure produced as heat leaks
into the continually evaporating liquid. Air, being 21% oxygen, must be
kept out of contact with liquid hydrogen to prevent accumulation of
potentially explosive oxygen concentrations. Therefore, always store and
handle liquid hydrogen under positive pressure and in closed systems to
prevent the infiltration and solidification of air or other gases.
Keep exterior surfaces clean to prevent combustion. Atmospheric air
will condense on exposed liquid hydrogen-cooled surfaces, such as
vaporizers and piping. Nitrogen, having a lower boiling point than oxygen,
will evaporate first from condensed air, leaving oxygen enriched liquid. To
prevent the possible ignition of grease, oil or other combustible materials
which could come into contact with the air-condensing surfaces, such
areas must be cleaned to oxygen-clean standards. Consult CGA pamphlet
G-4.1 “Cleaning Equipment for Oxygen Service” (see page 15).
Extreme cold – Cover eyes and exposed skin. Accidental contact with
liquid hydrogen or cold issuing gas with the skin or eyes may cause a
freezing injury similar to frostbite. Handle the liquid so that it won’t splash
or spill. Protect your eyes and cover the skin where the possibility of
contact with the liquid, cold pipes and cold equipment, or the cold gas
exists. Safety goggles or a face shield should be worn if liquid ejection or
splashing may occur or cold gas may issue forcefully from equipment.
Clean, insulated gloves that can be easily removed and long sleeves are
recommended for arm protection. Cuffless trousers should be worn or
over the shoes to she spilled liquid.
Keep equipment area well ventilated. Although hydrogen is non-toxic, it
can cause asphyxiation in a confined area without adequate ventilation.
Any atmosphere which does not contain enough oxygen for breathing can
cause dizziness, unconsciousness, or even death. Hydrogen being
colorless, odorless, and tasteless and cannot be detected by the human
senses. They will be inhaled normally as if gas were air. Without adequate
ventilation, the expanding gas will displace the normal air without warning
that a non life-supporting atmosphere is present. Store liquid
containers outdoors or in other well-ventilated areas.