Taylor-Wharton LABS Series - Manual (Page 5)

3
LABS
SAFETY PRECAUTIONS FOR LIQUID NITROGEN
Nitrogen is an inert, colorless, odorless, and tasteless gas making up four-fifths of
the air you breathe – and can be
hazardous. Air is roughly one-fifth oxygen. Liquid
nitrogen is at a temperature of -196°C (-320°F) under normal atmospheric pressure.
Extreme Cold - Cover Eyes and Exposed Skin
Accidental contact of liquid nitrogen 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 cold gas exists. Safety goggles or a face
shield should be worn when operating this equipment. Insulated gloves that can be
easily removed and long sleeves are recommended for arm protection. Trousers
without cuffs should be worn outside boots or over the shoes to shed spilled liquid.
Keep Equipment Area Well Ventilated
Although nitrogen is non-toxic and non-flammable, it can cause asphyxiation in a
confined area without adequate ventilation. Any atmosphere not containing enough
oxygen for breathing can cause dizziness, unconsciousness, or even death. Nitrogen is
a colorless, odorless, and tasteless gas that cannot be detected by the human senses
and will be inhaled normally as if it were air. Without adequate ventilation, the
expanding nitrogen will displace the normal air resulting in death or asphyxiation.
Liquid Nitrogen System
The liquid nitrogen supply pressure at the inlet to the refrigerator should be in
the range of 10 psig (0.7 bar/69 kPa) to 22 psig (1.4 bar/152 kPa) for optimum
performance. Higher operating pressures will increase transfer losses and create
excessive turbulence of the liquid in the refrigerator which can generate false signals
to the liquid level controller causing the refrigerator to under-fill. In “liquid phase”
storage applications, excessive turbulence can cause splashing which could result in
personal injury and/or damage to the refrigerator. When installing piping or fill hose
assemblies, make certain a suitable safety relief valve is installed in each section of
plumbing between shut-off and solenoid valves. Trapped liquefied gas will expand
rapidly as it warms and may burst hoses or piping causing damage or personal
injury. A relief valve is installed in the refrigerator plumbing to protect the line
between the customer supplied shut-off valve and the refrigerator solenoid valve.
For more detailed information concerning safety precautions and safe practices
to be observed when handling cryogenic liquids consult CGA pamphlet P-12
“Handling Cryogenic Liquids” available from the Compressed Gas Association,
1235 Jefferson Davis Highway, Arlington, VA 22202.
Dispose of Waste Liquid Nitrogen Safely
Dispose of waste liquid nitrogen out-of-doors where its cold temperature cannot
damage floors or driveways and where it will evaporate rapidly. An outdoor pit
filled with clean sand or gravel will evaporate liquid nitrogen safely and quickly.
WARNING:
The following safety
precautions are for
your protection.
Before installing,
operating, or
maintaining this unit
read and follow all
safety precautions
in this section
and in reference
publications. Failure
to observe all safety
precautions can
result in property
damage, personal
injury, or possibly
death.
Caution:
When installing field
fabricated piping,
make certain a
suitable safety valve
is installed in each
section of piping
between shut-off and
solenoid valves.
WARNING:
Inlet pressure should
not exceed 22 psig
(1.5 bar/152 kPa).
Higher pressures
could result
in damage to
equipment.
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