Hazard Management: Identifying Chemical Hazards

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Questions and Answers

What is a hazard?

Only physical objects that cause harm

Only chemicals that can cause fire or explosion

Any source or situation that causes death, bodily injury, damage to equipment, or delay to operations (correct)

Only situations that cause emotional distress

What is a chemical hazard?

Any chemical source that can cause fire, explosion, or has a toxic/harmful effect on health (correct)

Only chemicals that are highly flammable

Any chemical source that has a toxic or harmful effect on health

Any chemical source that can cause fire or explosion

What is the fire triangle?

Fuel, oxygen, and heat (correct)

Fuel, heat, and chain reaction

Oxidizer, heat, and fuel

Fuel, oxygen, and chain reaction

What is the fire tetrahedron?

Oxygen, heat, fuel, and chain reaction Signup and view all the answers

What is the purpose of equipment bonding and grounding?

To eliminate charge buildup and potential for electrostatic sparks Signup and view all the answers

What is the purpose of removing fuel in fire prevention?

To shut off fuel supply to prevent fire from spreading Signup and view all the answers

What is the purpose of portable fire extinguishers?

To be the first line of defense to stop fires before they get out of hand Signup and view all the answers

What is interrupting the chemical chain reaction in fire control?

Capturing free radicals using an extinguishing agent Signup and view all the answers

What is the primary function of water in firefighting?

Removes heat Signup and view all the answers

Which type of fire requires foam to extinguish?

Class A and B fires Signup and view all the answers

What is the characteristic of a combustion process that produces a rapid increase in temperature and pressure?

Rapid release of heat energy Signup and view all the answers

What is the primary mechanism of multipurpose dry chemicals in firefighting?

Excluding oxygen through coating surfaces Signup and view all the answers

What is the likely cause of a vapor cloud explosion?

Sudden release of large amounts of fuel due to rupture of a pipe or tank Signup and view all the answers

What is the primary difference between a fire and an explosion?

Rate of heat release Signup and view all the answers

What is the characteristic of a Boiling-Liquid Expanding-Vapor Explosion (BLEVE)?

Pressurized vessel containing a liquid above its boiling point ruptures Signup and view all the answers

What situation is characterized by the rapid combustion of fine solid particles?

Dust explosion Signup and view all the answers

Study Notes

Hazard Definition

A hazard is anything that can cause death, bodily injury to people, damage to equipment, or delay to operations.

Chemical Hazards

Chemical hazards are sources that can cause fire, explosion, or toxic/harmful effects on health when exposed.

Fire Hazards

Causes of fire:
- Burns
- Asphyxiation (smoke, toxic fumes)
Fire triangle: oxidizer, ignition (heat), fuel
Fire tetrahedron: oxygen, heat, fuel, and chain reaction
Chemical chain reaction: oxidation of fuel in the presence of O2 with emission of heat and light

Fuel Types

Liquids: gasoline, acetone
Solids: wood dust, metal particles
Gases: hydrogen, propane

Oxidizers

Liquids: hydrogen peroxide, nitric acid
Solids: metal peroxides, ammonium nitrite
Gases: oxygen, chlorine

Ignition Sources

Sparks
Flames
Heat
Static electricity: contact and separation of 2 surfaces with different conductivity

Preventing Fires

Equipment bonding and grounding: eliminates charge buildup and potential for electrostatic sparks
Removing fuel: shut off fuel supply to fires
Reducing oxygen: foam, displace oxygen with inert gas
Removing heat: applying water for cooling
Interrupting chemical chain reaction: capture free radicals using an extinguishing agent

Portable Fire Extinguishers

1st line defense to stop fire before it gets out of hands
Contain a fire until help comes
Class A: ordinary combustible materials like wood and paper
Class B: flammable liquids, solvents, oils, paint
Class C: flammable gases
Class D: combustible metals
Class F: cooking media in cooking appliances

Fire Extinguishing Agents

Water:
- Removes heat
- Effective for Class A fires
- Not for electrical source of ignition
Foam:
- Excludes oxygen from burning liquid fires, removes heat
- Fire can re-ignite if foam breaks down
- Effective for Class A and B fires
Inert gases:
- Displaces oxygen
- Examples: carbon dioxide, nitrogen
- Effective for Class A and B fires
Multipurpose dry chemicals:
- Excludes oxygen through coating surfaces
- Monoammonium phosphate
- Effective for Class A and B fires

Chemical Hazards – Explosions

Uncontrolled combustion producing rapid increase in temperature and pressure
Differences between fire and explosion:
- Combustion occurs at surface (fire) vs. entire fuel (explosion)
- Slow release of heat energy (fire) vs. rapid release of heat energy (explosion)
- No pressure wave generated (fire) vs. pressure wave generated due to rapid volume expansion (explosion)

Vapor Cloud Explosions

Ignition of vapor cloud of flammable material
Sudden release of large amounts of fuel due to rupture of a pipe or tank
Formation of large vapor cloud in its flammable range
Delayed ignition would result in vapor cloud explosion

Boiling-Liquid Expanding-Vapor Explosions

Pressurized vessel containing a liquid above its boiling point ruptures in a fire and releases pressurized liquid rapidly into the fire
Fire develops adjacent to a pressurized tank containing a liquid above its boiling point
Tank ruptures explosively, vaporizing its contents

Dust Explosion

Rapid combustion of fine solid particles
Occurs when fine particles are suspended in air and ignited

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Description

This quiz covers the definition of hazards, specifically chemical hazards, and their effects on health and safety. It also touches on the fire triangle and tetrahedron, and how chemical chain reactions can lead to hazardous situations.