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

6
Safe Refrigerant Handling
Oxygen displacement
All refrigerants will displace air if released, and when oxygen levels
are depleted, asphyxiation of people (and animals) occurs. Often,
this is manifest by a loss of consciousness without the individual
being aware that it is happening. Furthermore, most refrigerants
are denser than air, which means that rooms below ground, seated
areas, and enclosed spaces are more susceptible. Since most
refrigerants are odourless, occupants may not be aware that oxygen
is being displaced, and may become asphyxiated before they
become aware of this problem.
If a large release of refrigerant occurs, the area should be evacuated
immediately. Good ventilation must be provided in areas where high
concentrations of the vapour could accumulate. Once the area is
evacuated, it must be ventilated using blowers or fans to circulate
the air at floor-level: the lowest point possible. Before performing
maintenance in areas where refrigerants could have accumulated,
a thorough assessment must be carried out in order to determine
whether respiratory protection is required.
It is worth noting that within the field of RAC, there have been more
fatalities associated with oxygen displacement than with any other
aspect. It is essential to use appropriate breathing apparatus to
retrieve someone who has lost consciousness.
Toxicological effects
All refrigerants have some toxicological effects, primarily when
inhaled, but also if they are ingested or come into contact with skin
or other body parts. Normally, the various toxicological effects are
considered according to the potentially dangerous concentrations,
and for each substance, maximum concentrations are issued.
Many countries tend to have their own criteria, definitions and allowable
concentrations. However, across most countries, there are two values, which
are based on exposure in the workplace:
• A long-term exposure limit, based on an 8-hour time weighted
average reference period, and
• A short-term exposure limit, based on a 15-minute time
weighted average reference period
The long-term exposure limit represents the allowable concentration
that workers can be constantly exposed to during their working
hours, without any adverse effects. The short-term exposure limit
applies to the maximum concentrations that can be tolerated by
most people in the event of a catastrophic release, where they
need to make an emergency escape. Concentrations are normally
specified in parts per million (ppm) or milligramme (mg) per m3.
These exposure limits have different names in different countries.
For example, in the UK they are termed the Workplace Exposure
Limits (WEL), in Japan, France and Germany they are Occupational
Exposure Limits (OEL), in the USA they are Permissible Exposure
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