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ignited by a high energy source. It can decompose at high temperatures
forming toxic gases such as hydrogen chloride, chlorine and phosgene.
Closed containers may rupture and explode if heated. Trichloroethylene
vapours may accumulate in low-lying areas. The vapour causes irritation
of the nose and throat. Trichloroethylene is also a central nervous
system depressant. The vapour may cause headache, nausea, dizziness,
drowsiness, incoordination and confusion. High vapour concentrations
may cause unconsciousness and death. Trichloroethylene causes skin
and eye irritation and it is an aspiration hazard. Swallowing or vomiting
of the liquid may result in aspiration (breathing) into the lungs.
Trichloroethylene is a suspect cancer hazard, which may cause cancer
based on human information, and a possible reproductive hazard that
may cause birth defects, based on animal information, and a mutagen
that may cause genetic damage, based on animal information.
Trichloroethylene is predominantly used for vapour degreasing of
metal parts in the automotive and metal industries. It is also used as a
component of adhesives and as a solvent in paint-strippers, lubricants,
paints, varnishes, pesticides, cold metal cleaners, rubbers and elastomers.
It is used as a low temperature heat-transfer medium and as a chemical
intermediate in the production of pharmaceuticals, flame retardant
chemicals and insecticides. It is used in metal phosphatising systems,
textile processing, the production of polyvinyl chloride and aerospace
operations. 77
Short-term exposure to trichloroethylene causes irritation of the nose and
throat and central nervous system (CNS) depression, with symptoms
such as drowsiness, dizziness, giddiness, headache, loss of coordination.
High concentrations have caused numbness and facial pain, reduced
eyesight, unconsciousness, irregular heartbeat and death. 78
The effect of refrigerants with high ODP
The environmental friendliness of a refrigerant is a major factor in
assessing the usefulness of a particular refrigerant. The important
environmental and safety properties are:
Ozone Depletion Potential (ODP): The ODP of refrigerants should be
zero, i.e., they should be non-ozone depleting substances. Refrigerants
having non-zero ODP have either already been phased-out (e.g. R 11,
R 12) or will be phased-out in the near future (e.g. R 22). Since ODP
depends mainly on the presence of chlorine or bromine in the molecules,
refrigerants having either chlorine (i.e. CFCs and HCFCs) or bromine
cannot be used under the new regulations.
Other important environmental and safety properties:
• Global Warming Potential (GWP)
• Total Equivalent Warming Index (TEWI)
• Toxicity
• Flammability
Refrigerant
R 11 (CFC)
ODP = 1.0
GWP = 3500
R 12 (CFC)
ODP = 1.0
GWP = 7300
R 22 (HCFC)
ODP = 0.05
GWP = 1500
R 134a (HFC)
ODP = 0.0
GWP = 1200
Application
Large air conditioning systems
Industrial heat pumps
As foam blowing agent
Domestic refrigerators
Small air conditioners
Water coolers
Small cold storages
Air conditioning systems
Cold storages
Used as replacement for R 12 in domestic refrigerators,
water coolers, automobile A/Cs etc.
Substitute suggested
Retrofit ( R )/New (N)
R 123 (R,N)
R 22 (R,N)
R 134a (R,N)
R 227ea (N)
R 401A, R 401B (R,N)
R 411A, R411B (R,N)
R 717 (N)
R 410A, R 410B (N)
R 417A (R,N)
R 407C (R,N)
R 507, R507A (R,N)
R 404A (R,N)
R 717 (N)
No replacement required
- Immiscible in mineral oils
- Highly hygroscopic
R 717 (NH 3
)
ODP = 0.0
GWP = 0.0
R 744 (CO 2 )
ODP = 0.0
GWP = 1.0
R 718 (H 2 O)
ODP = 0.0
GWP = 1.0
R 600a (iso-butane)
ODP = 0.0
GWP = 3.0
Cold storages
Ice plants
Food processing
Frozen food cabinets
Cold storages
Air conditioning systems
Simultaneous cooling and heating (Transcritical cycle)
Absorption systems
Steam jet systems
Replacement for R 12
Domestic refrigerators
Water coolers
No replacement required
- Toxic and flammable
- Incompatible with copper
- Highly efficient
- Inexpensive and available
No replacement required
- Very low critical temperature
- Inexpensive and available
No replacement required
- High freezing point
- Large specific volume
- Inexpensive and available
No replacement required
- Flammable
Table 18: Applications of common refrigerants and suggested substitutes 79
77) Canadian Centre for Occupational Health and Safety, Trichlorethylene, 1999.
78) Canadian Centre for Occupational Health and Safety, Health effects of Trichloethylene, 1999.
79) Scribd, 26 Refrigerants, undated
75