White phosphorus is an example of:

Spontaneously combustible material

Potassium cyanide is an example of:

Division 6.2 Infectious substance

The nine hazard classes and their divisions – CDL Hazardous Materials (H) study guide

Every hazardous material is put in a hazard class that shows its main risk. There are nine classes, and some are split into divisions (for example 2.1). The class number appears on labels and placards, so you must know them by number and name.

Class 1 to Class 3

Class 1 – Explosives

1.1 Mass explosion – example: dynamite.
1.2 Projection hazard – example: flares.
1.3 Fire hazard – example: display fireworks.
1.4 Minor explosion – example: ammunition.
1.5 Very insensitive – example: blasting agents.
1.6 Extremely insensitive – example: explosive devices.

Class 2 – Gases

2.1 Flammable gases – example: propane.
2.2 Non-flammable gases – example: helium (oxygen is also a common Class 2 example).
2.3 Poisonous/toxic gases – example: fluorine, compressed.

Class 3 – Flammable liquids – examples: gasoline, acetone.

Class 4 to Class 6

Class 4 – Flammable solids

4.1 Flammable solids – example: ammonium picrate, wetted (matches and fuses are other examples).
4.2 Spontaneously combustible – example: white phosphorus.
4.3 Dangerous when wet – example: sodium.

Class 5 – Oxidizers and organic peroxides

5.1 Oxidizers – example: ammonium nitrate (also hydrogen peroxide).
5.2 Organic peroxides – example: methyl ethyl ketone peroxide.

Class 6 – Poisons and infectious substances

6.1 Poison (toxic material) – example: potassium cyanide (pesticides and arsenic are others).
6.2 Infectious substances – example: anthrax virus.

Class 7 to Class 9 and the extra categories

Class 7 – Radioactive – examples: uranium, plutonium.
Class 8 – Corrosives – examples: battery fluid, hydrochloric acid.
Class 9 – Miscellaneous hazardous materials – examples: polychlorinated biphenyls (PCB), formaldehyde, asbestos.

Besides the nine classes there are two extra categories:

ORM-D (Other Regulated Material–Domestic) – consumer items such as food flavorings, medicines, hair spray or charcoal. Note: federal rules phased out ORM-D at the end of 2020; such items now usually travel as limited quantity packages. The test may still use the term.
Combustible liquids – examples: fuel oil, lighter fluid. They burn, but less easily than Class 3 flammable liquids.

Why it matters: the class tells responders what kind of danger they face (blast, fire, poison, radiation, burns). It also decides which labels and placards you need and which materials cannot be loaded together. A material can meet more than one class definition but is assigned to only one hazard class; extra hazards are shown with subsidiary labels or placards.

References and scope

The topic reference is listed below. Sources support verification; the lesson itself is here. The current content needs technical and language review before public launch.

Manual reference: 9.3.1

Official CDL handbook · Utah ↗States Our editorial approach

Put it into practice

Educational questions with explanations. The answer review also works without the interactive quiz.

Preparing your questions…

Review questions with answers

How many hazard classes are there?
1. 5
2. 6
3. 12
4. 9
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9
There are nine hazard classes.
Division 1.1 explosives are a:
1. Mass explosion hazard
2. Minor explosion hazard
3. Projection hazard
4. Very insensitive material
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Mass explosion hazard
1.1 is mass explosion (example: dynamite).
Ammunition is an example of which division?
1. 1.1
2. 1.3
3. 1.4
4. 1.6
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1.4
Division 1.4 (minor explosion) includes ammunition.
Blasting agents belong to Division:
1. 1.2
2. 1.5
3. 2.1
4. 5.1
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1.5
Division 1.5 (very insensitive) includes blasting agents.
Display fireworks are an example of Division 1.3, which is a:
1. Mass explosion hazard
2. Minor explosion hazard
3. Extremely insensitive material
4. Fire hazard
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Fire hazard
Division 1.3 is fire hazard, such as display fireworks.
Propane is in which division?
1. 2.1 Flammable gases
2. 2.2 Non-flammable gases
3. 2.3 Poisonous gases
4. 3 Flammable liquids
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2.1 Flammable gases
Propane is a 2.1 flammable gas.
Helium is an example of:
1. Division 2.1
2. Division 2.3
3. Division 2.2
4. Class 9
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Division 2.2
Helium is a 2.2 non-flammable gas.
Division 2.3 is:
1. Flammable gas
2. Poisonous/toxic gas
3. Non-flammable gas
4. Infectious substance
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Poisonous/toxic gas
2.3 is poisonous/toxic gas (example: fluorine, compressed).
Gasoline belongs to which hazard class?
1. Class 2
2. Class 8
3. Combustible liquids
4. Class 3
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Class 3
Gasoline is a Class 3 flammable liquid.
Sodium, which reacts with water, is in Division:
1. 4.3 Dangerous when wet
2. 4.1 Flammable solid
3. 4.2 Spontaneously combustible
4. 5.1 Oxidizer
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4.3 Dangerous when wet
Sodium is the example for 4.3 dangerous when wet.
White phosphorus is an example of:
1. Flammable liquid
2. Oxidizer
3. Spontaneously combustible material
4. Corrosive
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Spontaneously combustible material
White phosphorus is the example for 4.2 spontaneously combustible.
Ammonium nitrate is in which division?
1. 4.1
2. 5.1
3. 5.2
4. 6.1
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5.1
Ammonium nitrate is a 5.1 oxidizer.
Division 5.2 is:
1. Oxidizers
2. Poisons
3. Flammable solids
4. Organic peroxides
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Organic peroxides
5.2 is organic peroxides (example: methyl ethyl ketone peroxide).
Potassium cyanide is an example of:
1. Division 6.1 Poison
2. Division 6.2 Infectious substance
3. Class 8 Corrosive
4. Class 9 Miscellaneous
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Division 6.1 Poison
Potassium cyanide is a 6.1 poison (toxic material).
Anthrax virus is in which division?
1. 6.1
2. 7
3. 6.2
4. 9
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6.2
Anthrax is a 6.2 infectious substance.
Uranium is a Class ___ material.
1. 6
2. 7
3. 8
4. 9
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7
Uranium is Class 7 radioactive.
Battery fluid is an example of which class?
1. Class 3
2. Class 5
3. Class 9
4. Class 8
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Class 8
Battery fluid is a Class 8 corrosive.
Polychlorinated biphenyls (PCB) are in which class?
1. Class 9 Miscellaneous
2. Class 6 Poison
3. Class 3 Flammable
4. Class 2 Gas
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Class 9 Miscellaneous
PCBs are Class 9 miscellaneous hazardous materials.
Fuel oil is classified as a:
1. Flammable gas
2. Corrosive
3. Combustible liquid
4. Oxidizer
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Combustible liquid
Fuel oil is the example given for combustible liquids.
Food flavorings and medicines shipped as consumer commodities were listed as:
1. Class 4.1
2. ORM-D
3. Class 6.2
4. Division 2.2
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ORM-D
ORM-D (Other Regulated Material–Domestic) examples are food flavorings and medicines.
A material that meets the definition of more than one hazard class is assigned to:
1. Only one hazard class
2. Every class it meets
3. Class 9 automatically
4. No class
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Only one hazard class
A material may meet several definitions but is assigned to only one hazard class.
Flares are an example of which explosive division?
1. 1.4 Minor explosion
2. 1.6 Extremely insensitive
3. 1.1 Mass explosion
4. 1.2 Projection hazard
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1.2 Projection hazard
Division 1.2 projection hazard includes flares.