1540 Ch 1 PowerPoint

1. Fire Protection Systems
Third Edition
Chapter 1 — Basics of Fire Behavior

2. Objectives
‣ Describe the difference between fire and combustion.
‣ Identify and describe the elements of the fire triangle.
‣ Identify and describe the elements of the fire tetrahedron.
‣ List and describe the different types of fire.

3. Objectives
‣ List and describe the different stages of fire.
‣ List and describe forms of heat transfer.
‣ List and describe methods used to extinguish fires.
‣ List and describe the classes of fire and their relationship to
extinguishing agents.

4. Introduction
‣ It is necessary to understand fire behavior as it relates to the
hazards present.
‣ Factors affecting hazard fuel load:
‣Occupancy and use conditions
‣Construction materials
‣Materials present within a building
‣Storage of items

5. Introduction
‣ Fire protection systems must be adequate for conditions of
occupancy and use.
‣ Update preplan and response protocols as needed.
‣ Reevaluate systems as needed.
‣ Basic understanding of fire chemistry and dynamics is needed to
assess fire hazards.

6. Combustion and Fire
‣ Combustion versus fire
‣ Combustion is a chemical reaction involving combustible
materials and an oxidizing agent producing heat or energy.
‣ Fire is a chemical reaction producing energy in the form of
heat, light, and flame.
‣ The difference:
‣With combustion, the released energy stays in the
reaction to continue it.
‣With fire, energy is dissipated as light and heat.

7. Combustion and Fire
‣ The fire triangle
‣ Illustrates how a fire is started
‣ All three elements must be present in sufficient quantities
for a fire to exist.
© Jones & Bartlett Learning

8. Combustion and Fire
‣ The fire tetrahedron
‣ Shows that chain reaction is necessary to sustain fire
‣ Illustrates a fire’s nature once ignition occurs
© Jones & Bartlett Learning

9. Fire and Flame Types
‣ Diffusion flame
‣ Most natural flaming fires are diffusion fires.
‣ Examples: lighting a match, campfire, structure fire
‣ Requires combustible gas
‣Visible flame is a gaseous reaction.

10. Fire and Flame Types
‣ Smoldering
‣ No flame, but significant heat
‣ Examples: charcoal on a grill, cigarette burning in an ashtray
‣ May precede a flaming fire
‣ May occur in the final phase of a fire event

11. Fire and Flame Types
‣ Spontaneous combustion/self-heating
‣ No known external source of heat
‣ Oxidation occurs in an environment that limits heat
dissipation, so heat stays in the reaction.
‣ Timing depends on the material and the environment.

12. Fire and Flame Types
‣ Premixed flame
‣ Used to help people get ready for the day or for
transportation
‣Cooking meals, driving to work, etc.
‣ Gas fuel and air must mix before ignition or combustion
occurs.
‣ Knowing flammable limits of gas fuels helps safely manage
incidents.

13. The Stages of Fire
‣ The incipient stage occurs when
heat, fuel, and oxygen come
together and generate more
heat than is dissipated.
‣ Uninhibited chain reaction
‣ No need for additional heat
sources (can self-sustain if
fuel/oxygen is sufficient)
Courtesy of NIST.

14. The Stages of Fire
‣ In the growth stage (free
burning stage), adequate
oxygen must be available to
sustain the fire.
Fire growth is affected by
numerous factors:
‣ Oxygen supply
‣ Amount/type of fuel
‣ Container size/structure
‣ Insulation Courtesy of NIST.

15. The Stages of Fire
‣ In the growth stage, the size of a structure and the shape of
walls, ceilings, and roofs also impact fire growth.
‣ Large compartments allow heat to dissipate.
‣ Low ceilings hold heat and reflect radiant heat energy.
‣ Ability of container to retain heat (insulation) accelerates
preheating of fuel.
‣ Flashover is a term describing the transition between the
growth and fully developed stages.

16. The Stages of Fire
‣ Fully developed stage
‣ Consumes all available fuel
‣ Releases most amount of heat
produced from the available
oxygen and fuel
‣ Once the heat release is high
enough, heat transfer occurs
to start fires in the adjacent
areas.
Courtesy of NIST.

17. The Stages of Fire
‣ The smoldering/decay stage
occurs when available fuel is
exhausted or oxygen level drops
below 16 percent.
‣ Burning only continues as
glowing combustion or
smoldering.
Courtesy of NIST.

18. Forms of Heat Transfer
‣ Conduction
‣ Transfer of heat from one
body of material to another
by direct contact
‣ Rate of transfer depends on
the efficiency of material as
conductor.
© Jones & Bartlett Learning

19. Forms of Heat Transfer
‣ Convection
‣ Transfer of heat from one
body of material to another via
liquid or gas
‣ Convection effect is influenced
by the size and shape of fire
compartment.
© Jones & Bartlett Learning

20. Forms of Heat Transfer
‣ Radiation
‣ Transfer of heat through
electromagnetic energy such as
light
‣ Radiant heat travels in a
straight line.
‣ Affects the speed of flashover in
structure fires
‣ Can cause fires to spread
© Jones & Bartlett Learning

21. Methods of Extinguishing Fires
‣ Cooling
‣ 1 gallon of water absorbs 8000
Btu.
‣ Water must be applied at
sufficient rate and quantity.
‣ Water cooling effectiveness
depends on:
‣ Fuel type
‣ Form of material
‣ Storage arrangement
© Jones & Bartlett Learning

22. Methods of Extinguishing Fires
‣ Oxygen reduction
‣ Fires are starved by controlling air
intake.
‣ Foam
‣ Carbon dioxide
© Jones & Bartlett Learning

23. Methods of Extinguishing Fires
‣ Removing or interrupting the fuel supply
‣ Backfires
‣ Smothers with foam
‣ Water can pre-wet adjacent fuels.
© Jones & Bartlett Learning

24. Methods of Extinguishing Fires
‣ Interrupting the chain reaction
‣ Suppression agents
‣Displace oxygen
‣Decompose or isolate material
from other elements
‣Change environment so more
energy is required for
combustion
© Jones & Bartlett Learning

25. Classes of Fire
‣ In the early 1900s, UL created a classification system on the
basis of extinguishing agents.
‣ Wrong agent will be ineffective and could compound the
hazard.
‣ Extinguishing agents are matched to fire hazards with letters of
the alphabet.

26. Classes of Fire
‣ Class A
‣ Involves ordinary combustibles
‣ Suppression:
‣Water (most effective)
‣Class A foam
© schankz/Shutterstock.

27. Classes of Fire
‣ Class B
‣ Involves flammable and combustible liquids and gases
‣ Suppression:
‣Smothering, blanketing
‣Foam
‣Carbon dioxide and
other gaseous agents
‣Dry chemical agents
‣Halons
© thaloengsak/iStock/Getty Images Plus/Getty Images.

28. Classes of Fire
‣ Class C
‣ Involves energized electrical
equipment
‣ Suppression:
‣Shut off electricity.
‣Once it is off, the fire
changes to another
classification.
© Shay Levy/PhotoStock-Israel/Alamy Stock Photo.

29. Classes of Fire
‣ Class D
‣ Involves combustible metals
‣ Suppression:
‣Extinguishing agents must
match metal type.
‣“Dry powder” agents
Andrew Lambert Photography/Science Source.

30. Classes of Fire
‣ Class K
‣ Involves cooking appliances
‣ UL 300 addressed failure of
suppression systems.
‣ Suppression:
‣Wet chemical agents
‣Supplemental hand-held
extinguishers
© Kathie Nichols/Shutterstock.