Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

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Refrigerant Management
Handling of refrigerants
Below are presented some aspects of the management of refrigerant
cylinders. Specific considerations about safety and care precautions
concerning the manipulation and direct contact with refrigerant itself are
presented in
Chapter 6 4
Refrigerant cylinders
Refrigerants are packed in both disposable and returnable (refillable)
shipping containers, commonly called “cylinders”. Disposables
are manufactured in sizes from 0.5 litres to 22 litres capacity
(corresponding to approximately 0.5 to 25 kg of CFC, HCFC or
HFC refrigerant). They are considered pressure vessels, and in most
countries therefore are subject to national regulations.
Containers are designed for pressurised and liquefied gases,
and are labelled accordingly. Some refrigerants are gases at
atmospheric pressure and room temperature, and are therefore
transported and stored as liquefied compressed gases in
pressurised cylinders. Other refrigerants are liquids at room
temperature and contained in drums, barrels or other standard
containers.
Numerous regulations are in force worldwide for the manufacture,
handling and maintenance of pressurised containers. Cylinders are
manufactured to specifications established by countries regulatory
authorities.
There are different types of cylinder:
Disposable and non-refillable cylinders 4
Refillable cylinders 4
Recovery cylinders 4
Normally, each cylinder is equipped with a safety-relief device that
will vent pressure from the cylinder before it reaches the rupture
point, in the event of, say, overheating. When temperatures increase,
the liquid refrigerant expands into the vapour space above the liquid
causing the pressure to rise gradually as long as a vapour space is
available for expansion. However, if no vapour space is available due
to an overfilled cylinder and no pressure-relief valve is available, the
liquid will continue to expand with no room for the expanding liquid
and will result in extremely high pressures with the consequence
of the cylinder rupturing. When the cylinder ruptures, the pressure
drop causes the liquid refrigerant to flash into vapour and sustains
explosive behaviour. The rupture of a refrigerant cylinder containing
liquid refrigerant that flashes into vapour is far worse than the rupture
of a compressed-air cylinder of the same pressure. The next pages
include information on cylinder management plans.
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