Safety in the use and handling of refrigerants is related to four
aspects: toxicity, the carcinogenic and mutagenic potentials and the
flammability. Recommendations regarding the suitability of levels of toxicity as well as flammability limits can be found in several publications, although the data do not always coincide. Nevertheless, such examples, regarding the relative toxicity and flammability of the various refrigerants.
A classification of soft drinks for safety is that recommended by the
standard ASHRAE 34, which has served as a reference to other standards. The soft drinks
are divided into three groups:
Group 1: Non-combustible, non-flammable refrigerants under normal conditions of
use. Its degree of toxicity is characterized by not causing death or disturbances
sera exposed to a 2 hour exposure to an atmosphere of 2.5% refrigerant concentration by volume.
Group 2: In this case the refrigerants may be flammable. An atmosphere of 2.5% by volume of the refrigerant can cause serious disturbances to guinea pigs submitted to them for a period of two hours.
Group 3: The refrigerants in this group are flammable, but their toxicity is
characterized in a similar way to Group 1 soft drinks.
The industrial refrigerants considered in this chapter fall within the following
in the ASHRAE 34:
Group 1: R-12, R-13, R-22, R-502 and carbon dioxide.
Group 2: Ammonia
Group 3: Hydrocarbons: ethane, propane and butane.
Note: R-503 refrigerant has not been rated at this time.
Underwrites laboratory (UL) classifies soft drinks for effects on
proposing three groups:
Group 2 Gases or vapors which in concentrations ½ to 1% (5000 to 10000 ppm), for
periods of exposure of approximately half an hour, are lethal or produce serious disturbances: ammonia.
Group 5 Gases or vapors which in concentrations of 2 to 20% by volume, for
periods of exposure in approximately 2 hours are lethal or produce serious
disturbances: R-22 and carbon dioxide.
Group 6 Gases or vapors which in a concentration of 20% by volume, for periods
of exposure in approximately 2 hours are lethal or produce serious disturbances:
R-12.
