Chapter 8: Hazard Identification

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Hazard Identification

Objectives: By the end of this section, participants will be able to assess hazards given standard reference materials.

Why this section is important: Most workplaces have multiple hazards. By recognizing potential hazards, an employee may avoid potential hazards and an employer may avoid potential liability and lost revenues.

Fire Hazards

The four components of a fire comprise the Fire Tetrahedron:

Fuel

Heat (ambient temperature must exceed flashpoint temperature)

Oxygen

Chain Reaction

Note: The Fire Tetrahedron replaced the former Fire Triangle.

Classes of Fire
Class A (A for "ash")	The combustion of paper, wood, cloth, and some rubber and plastic material.
Class B (B for liquid "boils")	The combustion of flammable or combustible liquids, flammable gases, greases and similar materials, and some rubber and plastic materials.
Class C (C for "conducts")	Involve energized electrical equipment where safety to the employees requires the use of electrically nonconductive extinguishing media.
Class D (D for metal "dents")	The combustion of combustible metals such as magnesium, titanium, zirconium, sodium, lithium and potassium.

Fire Extinguishers
Extinguisher Type	Suitable Class

Water	A
CO₂	A, B, C
Dry Chemical	A, B, and some C
Halon	A, B, C
Specialized Dry Agents	D
How to Use Fire Extinguishers: 1. 2. 3. 4.

Classification of Liquids
Class	Flashpoint (°F)	Boiling Point (°F)

Flammable Liquids
IA	_<73	<100
IB	<73	>100
IC	>73	<100

Combustible Liquids
II	>100	<140
IIIA	>140 & <200
IIIB	>200

Pyrophoric Liquids
Ignite in air at 130 F but do not require heat, shock or friction for ignition (e.g., Phosphorus, Titanium Dichloride, and Tributylaluminim)

Examples of Components of Combustion
Fuels	Oxidizers	Ignition Sources

Flammable Liquids Acetone Alcohol Hexane Toluene Pentane	Gaseous Oxygen Fluorine Nitrous Oxide Oxygen Difluoride Ozone	Flames Sparks Static Electricity Heat Electrical Equipment Cigarettes Light Bulbs Heaters Lightning Catalytic Surface Lasers Self-heating
Flammable Solids Plastics Fibers Wood / Paper Dust Pyrophoric Materials	Liquids Hydrogen Nitric Acid Perchloric Acid Bromine
Flammable Gases Acetylene Propane Carbon Monoxide Hydrogen Ethylene Oxide	Solids Metallic Perclorates Metallic Peroxides Ammonium Nitrate Ammonium Nitrite

Common Explosive Chemicals
Groups	Examples

Acetylenic Compounds	Acetylene, Copper (1) Acetylide, Ethoxyacetylene, Propyne, Propyne Peroxide, Disilver Acetylene
Azides	Benzenesulphonyl Azide, Carbonyl Diazide, Silver Azide, Lead (II) Azide, Azo Compounds, Diazirine, Azomethane, Diazomethane
Chloride / Chloro / Perchloro Compounds	Silver Chlorite, Silver Chlorate, Potassium Chlorite, Lead Tetrachloride
Fulminates	Silver Fulminates, Mercury (II) Fulminate, Sodium Fulminate, Copper (II) Fulminate
Nitrogen-bearing Compounds	Nitromethane, Nitroglycerine, Nitrocelluose, Trinitrotoluene (TNT), Silver Amide, Silver Nitride, Nitrocylcyanide, Disulfur Dinitride
Picrates	Picric Acid, Lead Picrate
Peroxides	Diacetyl Peroxide, Zinc Peroxide, Dimethyl Peroxide
Ringed Compounds	Benzvalene, Prismane
Polymerizable Compounds	Acrylic Acid, Ethylene, Butydiene, Styrene, Vinyl Chloride, Cyclopentadiene

Precautionary Measures for Unstable Substances

Protect these materials from shock, elevated temperature, light, ignition sources, and other reactive chemicals

Store a minimum quantity of the material and do not store near an area populated by workers

Whenever possible, use the chemicals with added inhibitors

Store explosives in isolated, heavily constructed magazines. Preferably underground or at least in a building with blow-out walls.

Reactive Chemicals
Vigorously polymerize, decompose, condense, or become self-reactive under conditions of shock, pressure or temperature.
Chemical Group	Chemical	Examples

Alkali Metals	Alkali Metals	Lithium, Sodium
Organometallic Compounds	Anhydrides	Acetic Anhydride
	Halides	Acetyl Chloride
	Hydrides	Diborane, Sodium Hydride
	Peroxides	Sodium Peroxide
	Carbides	Calcium Carbide
	Oxides	Sodium Oxide
	Phosphide	Aluminum Phosphide
Air Reactive Chemicals	Metallic Dust	Zinc, Nickel, Titanium
	Alkali Metals	Cesium, Potassium
	Hydrides	Diborane, Barium Hydride
Polymerizable Chemicals: Monomers combined with other monomers	Polymerizable Chemicals	Ethylene
Oxidizers: Initiate or promote combustion in other materials		Fluorine, Nitrates, Ozone Nitrites, Chlorine, Nitrous Oxide, Persulfated Liquid, Oxygen, Peroxides, Liquid Air, Peroxy Acids, Chlorosulfonic Acid, Perchlorates, Nitromethane, Dichromates, Hypochlorites, Chromates, Chlorates, Permanganates, Nitric Acid, Hypochlorites
Reducers: Initiate or promote combustion in other materials.		Finely Divided Metals, Hydrazide, Hydrides, Hydrogen, Aniline, Sodium, Lithium, Potassium, Butadiene, Acetylides
Organic Peroxides: They are strong oxidizers		Organic Peroxides

Inhibitors of Reactive Chemicals
Reactive Chemical	Inhibitor

Picric Acid	Water
Methyl Vinyl Ether	Triethanolamine
Cyclonite	Bees Wax
Lead Azide	Water
Lead Styphnate	Water
Acrylaldehyde	Hydroquinone
Methyl Methacrylate	Water
Vinyl Chloride	Phenol
Tetrafluoroetheylene	Alphaterpinene
Chlorotrifluoroethylene	Tributylamine

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Explosives
High: Detonate from heat or shock	Low: Deflagrate (burn slowly)
Example: Ammonium Nitrate / Fuel Oil	Example: Black Powder