This document discusses scientific terminology related to fire and emergency services. It covers the three states of matter that fuel can exist in (solid, liquid, gas), defines key terms like density and specific gravity. It explains physical and chemical changes, the fire tetrahedron elements of fuel, oxygen, heat, and chain reaction. Combustion and the stages of fire development are described. Special hazards like rollover, flashover, and backdraft are also summarized.

1. Fire and Emergency Services
Orientation and Terminology
5th Edition
Chapter 5 — Scientific Terminology

2. REVIEW QUESTION
What are the three physical states of
matter that fuel can be found in?
5–1

3. Learning Objective 1
Describe the properties of matter.
5–2

4. There are three
physical states of matter.
Solid
Gas
Liquid
5–3

5. Matter can be described using
terms derived from its physical
properties of mass and volume.
Density
• Mass per unit of volume of a substance
Specific gravity
• Ratio of mass of given volume of liquid
compared with mass of equal volume of water
Vapor density
• Density of gas or vapor in relation to air
5–4

6. Physical and chemical changes
involve an exchange of energy.
When a substance
remains chemically
the same but
changes in size,
shape, or
appearance
Physical
Change
When a substance
changes from one
type of matter into
another
Chemical
Change
5–5

7. As fire consumes a fuel,
its mass is reduced.
Mass and energy cannot
be created or destroyed;
reduction in mass of a
fuel results in release of
energy - light and heat
More fuel to burn, more
potential for greater
amounts of energy being
released as heat during a
fire
The more heat that is
released, the more
extinguishing agent is
needed to control a fire
5–6

8. Learning Objective 2
Explain combustion, the fire
tetrahedron, and fire development.
5–7

9. Fire is one form of combustion.
Combustion is a rapid and
self-sustaining reaction that
releases energy in the form of
heat, light, and byproducts
Modes of combustion –
Differentiated based on
where the reaction is
occurring
5–8

10. For combustion to occur, four
components are necessary.
5–9

11. REVIEW QUESTION
What are the four elements of the fire
tetrahedron?
5–10

12. Heat is a form of energy.
Heat
• Potential energy
• Kinetic energy
Temperature
Energy
Ignition
• Piloted
• Autoignition
5–11

13. There are several sources
of heat energy.
Chemical
heat
energy
Self-heating
Electrical
heat
energy
Mechanical
heat
energy
5–12

14. Heat is transmitted
in three ways.
5–13
Conduction
(Continued)

15. Heat is transmitted
in three ways.
5–14

16. REVIEW QUESTION
How do conduction, convection, and
radiation influence the development of
fire?
5–15

17. Fuel is the material or substance
being oxidized or burned in
combustion process.
Solids
Pyrolysis
Surface-to-mass
ratio
Liquids
Vaporization
Volatility
Gases
Flammable/
explosive
range
Lower
flammable
limit
Upper
flammable
limit
5–16

18. Oxidizing agents release oxygen
or other oxidizing gases during a
chemical reaction.
Examples
Oxygen
Concentrations
5–17

19. REVIEW QUESTION
What chemical reaction do oxidizers
support when combined with a fuel?
5–18

20. The self-sustained chemical
reaction involved in flaming
combustion is complex.
5–19

21. A compartment fire is either
fuel- or ventilation-controlled.
5–20

22. There are five stages
of a compartment fire.
5–21

23. REVIEW QUESTION
What are the five major phases of fire?
5–22

24. Learning Objective 3
Describe special considerations of fire
that have particular implications for
firefighter safety.
5–23

25. Rollover may occur
during the growth stage.
Unburned fire gases at top of compartment ignite;
flames propagate through the hot gas layer or
across the ceiling
Distinguished from flashover; involves only fire gases
at upper levels of compartment
Will generally precede flashover, but may not always
result in flashover
5–24

26. REVIEW QUESTION
What is the difference between a
rollover and a flashover?
5–25

27. The thermal layering of gases is
the tendency of gases to form
layers according to temperature.
Hottest gases in
top layer, cooler
gases in lower
layers
Can be disrupted
with ventilation
Can be disrupted
if water applied
directly into the
layer
5–26

28. REVIEW QUESTION
What effect does thermal layering have
on fire suppression activities?
5–27

29. A backdraft is an instantaneous
explosion or rapid burning of
superheated gases.
5–28

30. Products of combustion are the
materials produced and released
during burning.
Smoke
Flames
5–29

31. Learning Objective 4
Discuss the four aspects of fire
extinguishment theory.
5–30

32. Fire is extinguished by limiting
one or more of the elements in
the combustion process.
5–31

33. REVIEW QUESTION
What are four main fire extinguishment
techniques?
5–32

34. Learning Objective 5
Define the five main classifications of
fires.
5–33

35. Each class of fire has its own
requirements for extinguishment.
Class A
Class B
Class C
Class D
Class K
5–34

36. Summary
• It is crucial that all firefighters understand
the science of fire if they are to operate
safely and efficiently on the fireground.
• This knowledge is important on the
fireground as emergency responders
continually evaluate the fire and determine
how to attack the fire itself, protect
exposures, and ensure the safety of
everyone at the scene.
5–35