Module 1: Regulations - International Association of Fire Fighters

IAFF Training for Hazardous Materials: Technician© Student Text
Division 2.3
Gases that are poisonous by inhalation are
known to be toxic to humans and, therefore,
pose a hazard to health during transportation.
Because all Division 2.3 materials are
poisonous-by-inhalation, they will be assigned
one of four hazard zones (A,B,C,D).
The hazard zone indicates the intensity of
the hazard. In general, Zone A is the “most
poisonous” and Zone D the “least poisonous.”
Zone definitions are based on an
established toxicity values (LC 50
) determined
from animal testing. For more
information on gases which are poison-byinhalation,
refer to 49 CFR 173.133. An
example of a compressed gas that is poisonous-by-inhalation
is hydrogen sulfide gas.
Hazard Zone InhalationToxicity
A
LC 50
< 200 ppm
B
C
D
200 ppm < LC 50
< 1000 ppm
1000 ppm < LC 50
< 5000 ppm
3000 ppm < LC 50
< 5000 ppm
Class 3 Flammable and
Combustible Liquids
Flammable Liquid
A flammable liquid is defined as “a liquid having a flash
point of not more than 60.5°C (141°F).” Examples of
Class 3 materials include acetone and isopropanol. Class 3
materials are divided into packing groups based on their
degree of danger. The following chart distinguishes among
Class 3 packing groups.
1-30 Module 1: Regulations