Cryogenic materials are compounds that have to be cooled to
an extremely low temperature to change from a gas to a liquid. It is important
to keep them at this low temperature to make sure they remain in the gas phase.
They are also known for their high expansion rate when the compound is in the
gas phase. Some examples of cryogenics are: helium, argon, nitrogen, methane,
and oxygen. Many cryogenic gases are flammable which could lead to fire and
explosion hazards in the workplace. When in use you must keep any ignition
sources away from the area where cryogenic gases are being used. Some examples
include: open flames, welding, and electrical equipment when not intrinsically
safe.
I found the equivalent of American OSHA, Occupational Safety
and Health Administration, but in Canada it is called the Occupational Health
and Safety or OSH. Their webpage had a ton of great information on how to work
safely with cryogenic gases. Their best “solution” to how to work safely with
cryogenic gases is to not work with them but to substitute them out for another
product. They did admit that this may not always be possible with a specific
job but they suggested communicating with your chemical supplier for a recommendation
on a safer substance. Another safety measure is to have the proper personal
protective equipment or PPE when handling cryogenic gases due to the extremely
low temperatures they are kept at any contact with the skin could cause serious
burn leading to frostbite. In the gas phase they can cause permanent damage to
the eyes and other delicate tissue with just a moments exposure. Workers must
not only protect their hands from burns but their full bodies as well. The
correct workmen personal protective equipment should include: full-face shield,
goggles, vinyl gloves specially designed to prevent cryogens from flowing into
the gloves, lab coats and high-top closed toed shoes.
When working with cryogenic gases there needs to be proper
ventilation to prevent asphyxiation of the workers, and the storage of the
containers should not be kept in enclosed spaces. Proper ventilation also
reduces the risk of fire or explosion in the workplace. The hoods, ducts, air
cleaners, and fans must be made from materials compatible with cryogenic gases
where they are being used or stored to avoid any problems.
Cryogenic liquefied gases are stored in heavily insulated
containers because they are kept at or near boiling point to keep it in the
liquid phase. However, since it is not perfect there is always some gas in the
containers. This could become a potentially dangerous situation if too much gas
begins to build up in the container due to the large expansion ratio from
liquid to gas, creating a buildup of high pressure in the container. Avoidance
of this issue is easy with the proper installment and appropriate use of a
pressure relief device on the container. Since these devices are so important
it is vital to check for leaks on a regular basis.
The Handout given in class: Physical Hazards Slides
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