Fire Hazard and Controls Module
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Questions and Answers

What is considered the most effective method to control fire hazards according to the Hierarchy of Controls?

  • Administrative controls
  • Elimination (correct)
  • Engineering controls
  • Personal protective equipment

Which of the following is NOT one of the inherently safer design principles?

  • Substitution
  • Simplification
  • Isolation (correct)
  • Minimization

Which control method involves creating systems to prevent or mitigate loss of containment?

  • Elimination
  • Inherent safety
  • Administrative controls
  • Engineering controls (correct)

What is the purpose of administrative controls in fire hazard management?

<p>To reduce risk through training and procedures (B)</p> Signup and view all the answers

Personal protective equipment is positioned at what level in the Hierarchy of Controls?

<p>As the final item on the hierarchy (C)</p> Signup and view all the answers

Which of the following actions would fall under the principle of substitution in inherently safer design?

<p>Using a less hazardous chemical in place of a toxic one (A)</p> Signup and view all the answers

Why is controlling the fuel source critical in fire hazard management?

<p>It collapses the fire triangle (D)</p> Signup and view all the answers

Which method is aimed at reducing risks by establishing protocols for safe work practices?

<p>Administrative controls (B)</p> Signup and view all the answers

Which method of inerting involves drawing a vacuum on the vessel before refilling it with inert gas?

<p>Vacuum inerting (C)</p> Signup and view all the answers

What is a significant danger associated with pressure inerting?

<p>Asphyxiation hazards (C)</p> Signup and view all the answers

Which inerting method is suitable for vessels that are not designed for pressure or vacuum?

<p>Sweep through inerting (C)</p> Signup and view all the answers

What is the primary hazard linked to open flames in an area where fuel and oxidants are present?

<p>They can ignite an explosive atmosphere. (A)</p> Signup and view all the answers

In siphon inerting, what is the role of the liquid added to the vessel?

<p>To displace the oxidant when drained (A)</p> Signup and view all the answers

Why might vacuum inerting be preferred over other inerting methods?

<p>It is simpler and avoids vacuum hazards. (B)</p> Signup and view all the answers

What is indicated by the saturation vapour pressure curve?

<p>The pressure exerted by gaseous particles at equilibrium (B)</p> Signup and view all the answers

What is a key disadvantage of pressure inerting compared to vacuum inerting?

<p>It cannot be used on all vessel types. (B)</p> Signup and view all the answers

What is the importance of knowing a liquid's flashpoint temperature?

<p>It assesses the risk of fire hazards (C)</p> Signup and view all the answers

Which of the following measures can help minimize ignition hazards?

<p>Extinguish open flames in critical areas (C)</p> Signup and view all the answers

Which statement accurately differentiates flammable from combustible liquids?

<p>Flammable liquids ignite below 38°C, while combustible liquids ignite at or above that temperature (C)</p> Signup and view all the answers

What happens to gaseous particles in a closed container over time?

<p>They continually switch between liquid and gas phases until equilibrium is achieved (A)</p> Signup and view all the answers

How is the flashpoint temperature typically estimated?

<p>As the intersection of the LFL with the saturation vapour pressure curve (C)</p> Signup and view all the answers

Which condition will increase the saturation vapour pressure of a liquid?

<p>Increasing the temperature of the liquid (C)</p> Signup and view all the answers

What characterizes a liquid with a flashpoint above 38°C?

<p>It is classified as combustible (B)</p> Signup and view all the answers

What occurs when the number of particles moving from liquid to gas equals the number returning?

<p>Both phases are in equilibrium (A)</p> Signup and view all the answers

What is the primary purpose of the NFPA-70 standard?

<p>To reduce fire or explosion risks from electrical systems (D)</p> Signup and view all the answers

How are hazardous areas classified according to the National Electrical Code?

<p>By class and division (C)</p> Signup and view all the answers

What does the 'Class' in the class and division system indicate?

<p>The general nature of hazardous materials (A)</p> Signup and view all the answers

What is one role of engineers in relation to hazardous classified areas?

<p>To determine explosion-proof requirements for electrical systems (C)</p> Signup and view all the answers

Which factor is NOT a flammability parameter that should be described?

<p>Heat of vaporization (A)</p> Signup and view all the answers

Which side of the fire triangle is primarily controlled by a flammable cabinet for storing certain chemicals?

<p>Fuel (D)</p> Signup and view all the answers

What must be ensured when transferring petroleum products in relation to the fire triangle?

<p>Control of ignition sources (B)</p> Signup and view all the answers

In terms of fire hazards, what does the classification of an area help engineers to assess?

<p>Explosion-proof design requirements (C)</p> Signup and view all the answers

What causes oily rags to spontaneously ignite?

<p>Accumulation of heat from oxidation (B)</p> Signup and view all the answers

Which of the following correctly describes adiabatic compression?

<p>Rapid pressure increase leading to a swift temperature rise (C)</p> Signup and view all the answers

How can the risk of fire hazards be effectively reduced?

<p>By implementing control measures across all aspects of the fire triangle (C)</p> Signup and view all the answers

What is the role of heat in the process of autoignition?

<p>It raises the temperature of the fuel-air mixture to its autoignition temperature (D)</p> Signup and view all the answers

What does the fire triangle consist of?

<p>Fuel, oxidant, and ignition (A)</p> Signup and view all the answers

Which scenario is an example of self-heating?

<p>Rags soaked in oil oxidizing and igniting in a garbage bin (D)</p> Signup and view all the answers

What happens when a gas is rapidly compressed?

<p>The temperature of the gas may surpass the autoignition temperature (C)</p> Signup and view all the answers

Which legislation addresses fire safety controls?

<p>National Building Code of Canada 2015 (A)</p> Signup and view all the answers

What are the three essential elements needed to create a fire according to the fire triangle?

<p>Fuel, Oxidant, Ignition Source (D)</p> Signup and view all the answers

Which of the following is considered an oxidant in combustion reactions?

<p>Oxygen gas (C)</p> Signup and view all the answers

Which source of energy can ignite a combustion reaction?

<p>Sparks from a switch (B)</p> Signup and view all the answers

What kind of materials are described as fuels for combustion?

<p>Oxygen-deficient materials (D)</p> Signup and view all the answers

Which example does NOT represent an oxidant?

<p>Sparks from a firework (D)</p> Signup and view all the answers

What can influence how easily a fuel ignites?

<p>The physical characteristics of the fuel (D)</p> Signup and view all the answers

Which of the following statements about the elements of the fire triangle is correct?

<p>A fuel can be a solid, liquid, or gas. (D)</p> Signup and view all the answers

What role does an oxidant play in combustion?

<p>It removes electrons from other reactants. (D)</p> Signup and view all the answers

Flashcards

What is combustion?

A chemical reaction between a fuel and an oxidant that releases energy in the form of heat and light.

What are the three elements of the fire triangle?

Fuel, oxidant, and ignition source. All three must be present for fire to occur.

What is an oxidant?

A substance that removes electrons from another reactant in a chemical reaction. Oxygen is a common example.

Give an example of a liquid oxidant.

Hydrogen peroxide is a liquid oxidant.

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What is an ignition source?

A source of heat that starts a combustion reaction.

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Give an example of a solid fuel.

Wood is a solid fuel.

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What is the relationship between fuel and combustion products?

Fuel is consumed in the combustion reaction, producing combustion products like carbon dioxide and water.

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How does moisture content affect fuel?

Moist fuel burns less readily than dry fuel because the moisture absorbs heat, slowing the combustion process.

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Saturation Vapour Pressure

The pressure exerted by the vapor of a liquid when it is in equilibrium with its liquid phase in a closed container. The saturation vapor pressure increases with increasing temperature.

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How is Saturation Vapour Pressure Measured?

The saturation vapor pressure of a liquid is represented by a curve on a graph. The concentration of the vapor when vapor and liquid are in equilibrium is indicated by this curve.

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Flashpoint Temperature

The lowest temperature at which a liquid produces enough flammable vapors to ignite in the presence of an ignition source.

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How is Flashpoint Temperature Estimated?

Flashpoint temperature can be experimentally determined OR estimated at the point where the LFL (lower flammable limit) intersects the saturation vapor pressure curve.

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Flammability Classification: Flammable Liquid

A liquid with a flashpoint temperature below 38°C (100°F). They are generally considered dangerous because they can ignite easily at normal working temperatures.

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Flammability Classification: Combustible Liquid

A liquid with a flashpoint temperature at or above 38°C (100°F). They are generally safer than flammable liquids because they typically require higher temperatures to ignite.

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Flammable vs. Combustible: Key Difference

Both types of liquids can burn, but flammable liquids ignite easily at typical working temperatures, while combustible liquids usually require higher temperatures to start burning.

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Importance of Flashpoint in Safety

Knowing the flashpoint of a liquid helps prevent fires. Processes happening below the flashpoint are safer than those happening above it.

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Hierarchy of Controls

A framework for managing risks by prioritizing control methods from most to least effective.

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Elimination

The most effective control method, completely removing the hazard.

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Inherent Safety (Design)

Designing systems to eliminate or minimize hazards from the start.

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Minimization

Reducing the amount of a hazard present.

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Substitution

Replacing a hazardous substance or process with a safer one.

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Moderation

Using a less hazardous form of a hazard.

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Simplification

Making processes easier and more direct to reduce error potential.

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Fuel Control

Controlling the fire hazard by managing the fuel source.

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Autoignition Temperature

The lowest temperature at which a fuel-air mixture can ignite spontaneously without a spark or flame.

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Self-heating

A process where heat generated by oxidation of a material accumulates faster than it dissipates, eventually reaching the autoignition temperature.

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Adiabatic Compression

Sudden temperature rise in a gas due to rapid compression, where heat cannot escape quickly enough.

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Adiabatic Compression Ignition

Combustion occurring when adiabatic compression of a flammable gas-air mixture raises its temperature above the autoignition temperature.

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Fire Triangle

A model illustrating the three essential elements needed for fire: fuel, ignition source, and oxidant.

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Hazard Control

Measures implemented to reduce the risk of fire hazards by targeting one or more components of the fire triangle.

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Ignition Control

Measures aimed at preventing the initiation of a fire by controlling ignition sources, like sparks, flames, or heat.

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What is inerting?

Inerting is a safety procedure that replaces oxygen with an inert gas to prevent fires or explosions. This eliminates one part of the fire triangle - the oxidant.

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What are the four common methods for inerting?

The four commonly used methods for inerting are vacuum inerting, pressure inerting, sweep-through inerting, and siphon inerting.

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Vacuum Inerting

Vacuum inerting is the most common method. It involves drawing a vacuum on the vessel, then filling it with inert gas, repeating until the desired oxygen concentration is reached.

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Pressure Inerting

Pressure inerting involves adding inert gas under pressure to the vessel, then venting it down to the desired pressure, repeating the process.

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Sweep-through Inerting

Sweep-through inerting introduces inert gas at one opening of a vessel while mixed gas is withdrawn from another opening.

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Siphon Inerting

Siphon inerting involves filling the vessel with liquid, then adding inert gas as the liquid is drained.

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What are some common open flame ignition sources?

Open flames are present in boilers, furnaces, and welding operations. They should be extinguished when fuel and oxidant are present to avoid ignition.

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How can we minimize ignition hazards?

We can minimize ignition hazards by controlling open flames, hot surfaces, and static electricity, which are common ignition sources.

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What is a hazardous location?

An area where flammable gases or vapors may be present, posing a risk of fire or explosion.

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What are the two classifications for hazardous locations?

Hazardous locations are classified by Class and Division. Class defines the type of hazardous material, while Division defines the likelihood of its presence.

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What is Class I in hazardous location classification?

Class I indicates the presence of flammable gases or vapors.

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What is Class II in hazardous location classification?

Class II indicates the presence of combustible dusts.

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What is Division 1 in hazardous location classification?

Division 1 means the hazardous material is likely to be present continuously or frequently.

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What is Division 2 in hazardous location classification?

Division 2 means the hazardous material is unlikely to be present, but could occur during abnormal conditions.

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What are explosion-proof electrical systems?

Electrical systems designed to prevent the ignition of flammable mixtures even if sparks or arcing occur within the device.

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Why is hazardous location classification important?

It helps engineers choose appropriate electrical equipment and design systems to minimize the risk of fire or explosions.

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Study Notes

Fire Hazard and Controls Module

  • This module covers fire hazards and controls.
  • Upon completion, learners should be able to identify and classify fire hazards, determine prevention and mitigation controls for targeting each side of the fire triangle.

Fire Triangle Elements

  • Fire requires three elements: fuel, oxidant, and ignition source.
  • Removing any of these elements prevents fire.

Flammability Parameters

  • Lower Flammability Limit (LFL): The lowest concentration of fuel vapor for a fire to occur.
  • Upper Flammability Limit (UFL): The highest concentration of fuel vapor for a fire to occur.
  • Flashpoint Temperature: The lowest temperature at which a liquid forms an ignitable mixture with air.
  • Autoignition Temperature (AIT): The lowest temperature at which a vapor-air mixture ignites without an ignition source.

Fire and Humans

  • Humans have controlled fire for over a million years.
  • Fire has been crucial for human development and history, both positive and destructive.
  • Historical examples of major fire incidents are documented, including The Great Chicago Fire, and the Grenfell Tower fire.
  • Currently, fires continue to be significant events causing loss of life and property.

Hierarchy of Controls

  • Elimination: The most effective control method involves completely removing the hazard.
  • Inherent Safety: Designing a process or system to reduce hazard risks.
  • Engineering Controls: Implementing systems to prevent or mitigate hazards.
  • Administrative Controls: Establishing safe work procedures and training to mitigate risks.
  • Personal Protective Equipment (PPE): Using protective equipment to safeguard individuals, but is the least effective.

Fire Hazards

  • Fuel Hazards: Controlling fuel sources to prevent fires is essential (examples include storage, quantity, and type).
  • Oxidant Controls: Controlling oxidants, which are often oxygen-rich materials, minimizing the amounts present.
  • Ignition Source Controls: Avoiding or eliminating ignition sources like open flames, hot surfaces, and static electricity to prevent fires.
  • Examples: Identifying flammable liquids, and their proper storage are important aspects of this section.

Static Electricity as an Ignition Hazard

  • Static electricity can build up leading to sparks.
  • This is particularly relevant when dealing with flammable liquids and electrical components.
  • Bonding and grounding can help prevent static buildup and associated risks.

National Electric Code Categories (NFPA 70)

  • Class I: Flammable vapors that are present at flammable concentrations.
  • Class II: Combustible dusts present at flammable concentrations.
  • Class III: Combustible dusts present but not likely to be in suspension.
  • Division 1: Flammable conditions are normally present.
  • Division 2: Flammable materials are usually within enclosed systems.

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Description

This module explores the various fire hazards and appropriate controls required to mitigate them. You will learn to identify the elements of the fire triangle as well as important flammability parameters that affect fire safety. By the end of this quiz, you will understand how to prevent and manage fire-related risks effectively.

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