Liquefied gases or cryogenic gas have
the potential for creating dangerous working environments. It is important
that those who use, handle or transport cryogenic gases should also know
their potential hazards. It is necessary for all users to know the
properties of the gas in the cylinders or containers and adhere to related
safety regulations. The most commonly used industrial gases that are stored
in their liquid state at their cryogenic temperature and popularly known as
cryogenic gases include argon, neon, helium, oxygen, hydrogen and nitrogen.
Each of these gases has their specific hazards and so proper care must be
taken to handle them. Because of extremely low temperatures and high rates
of conversion into gas for all cryogenic liquids, they lead to hazards like
explosion, extreme cold, fire, asphyxiation etc., and hence adequate
precautions and safety measures must be taken.
How to prevent hazards?
Ventilation
It is advisable not to uses large quantities of cryogens without proper
ventilation. In cases where liquid helium spill, it is safe to evacuate the
area immediately or prevent others from entering by "Do not enter"
signs. Wait for the dispersed gas to be replenished by the ventilation
system before re-entering the room.
Handling
Always handle cryogenic gases carefully. The extremely low temperature of
these gases lead to severe burns, severe freezing of tissues. Exposure to
these gases severely affect skin of hands and face. Avoid or stay away from
boiling and splashing of cold liquids or when cold vapors are released.
These occurs when inserting objects into the liquid or when charging a warm
container. So better to perform these operations at a slow speed to avoid
splashing. Besides this, you should not allow any unprotected part of your
skin to come in contact with the uninsulated pipes and cylinders containing
cryogenic liquids.
Safety Equipment
Whoever handles, transport, store or uses cryogenic gases must be properly
protected so that eyes, skin do not come in contact with the gas. The
recommended PPE includes:
- Loose fitting thermal insulated or leather long sleeve shirts,
trousers and gloves.
- Face shield
- Safety glasses
- Safety shoes for people involved in cylinder handling
Depending on the application, safety and special clothing suitable for
that application is advisable. In emergency case, safe contained breathing
apparatus (SEBA) is advisable.
Inert gas precautions
When handling cryogenic inert gases, the potential of asphyxiation must be
known. Whenever cryogenic liquids are handled in enclosed areas, oxygen
monitors are advisable. Never allow any person to work in an atmosphere
consisting less than 19.5% oxygen without supplied air.
Oxygen precautions
In the areas where liquid oxygen is stored or handled, it is advisable not
to permit smoking or open flames. Never allow liquid oxygen to come in
contact with any flammable substances. Some of the materials that react
explosively when they come in contact with liquid oxygen are grease, oil,
tar, kerosene, asphalt or dirt consisting oil or grease. Do not walk on
areas when there is spilled oxygen on asphalt or flammable substance. Any
clothing soaked or exposed to liquid oxygen must be immediately removed and
properly aired.
Hydrogen precautions
Just like liquid oxygen, in the areas of storing liquid hydrogen, smoking
or open flames should not be allowed. Liquid hydrogen should not be
transferred from one container to another because if it comes in contact
with oxygen, the oxygen will condense in the liquid hydrogen resulting into
a severe explosion. Liquid hydrogen can solidify air, thereby blocking
relief vents in the cylinder causing ruptures. Glass cylinders are allowed
for liquid hydrogen. Never allow any spilling of hydrogen it can create a
flammable cloud.
A quick recap
To avoid unnecessary hazards while handling or storing cryogenic
liquids, some handy tips are give below:
- Always wear personal protective equipment while handling
cryogenic gases.
- Only trained and qualified personal should be allowed to handle,
transport or storing cryogenic gases.
- Proper storage is essential for such gases.
- Cylinders should not be dragged or carried.
- Containers should not be used for other purposes except for
storing the specified gas.
- Magnets should not be used for lifting cylinders.
- Observe containers for loss of insulated vacuum.
- All cryogenic storage equipment must have proper pressure relief
vent system so as to avoid explosion or over pressurization etc.
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Cryo
Gas Handling
