1 Essentials of Fire Fighting 6 th Edition Firefighter I Chapter 5 Fire Behavior Replace with manual graphic on slide master Learning Objective 1 2 Explain the science of fire as it relates to energy, forms of ignition, and modes of combustion. 5 2 Understanding the physical science of fire can help firefighter safety. 3 5 3 There are two types of changes firefighters should understand. 4 5 4
The concept of energy is also important for firefighters to know. 5 5 5 There are two forms of energy that firefighters should know about. 6 Courtesy of Dan Madrzykowski, NIST 5 6 There are many types of energy and all can change from one type to another. 7 5 7 You should also know about how to measure and the exchange of energy. 8 5 8
There are two types of energy reactions that you should understand. 9 5 9 The process of ignition follows a sequence of steps. 10 5 10 Piloted and autoignition are the two forms of ignition. 11 5 11 Fire and combustion require similar conditions to occur. 5 12 12
The fire triangle is the oldest and simplest fire model. 13 5 13 The fire tetrahedron represents the uninhibited chain reaction that must be present for fire to occur. 14 5 14 There are several materials that affect both ignition and fire development. 15 5 15 The two types of combustion occur under different circumstances. 16 5 16
The products of combustion generate as fuel burns and changes chemical composition. 17 (Cont.) 5 17 The products of combustion generate as fuel burns and changes chemical composition. 18 (Cont.) 5 18 WARNING 19 Smoke is fuel and is always potentially flammable. Wear full PPE and SCBA anytime you work in smoke. 5 19 The products of combustion generate as fuel burns and changes chemical composition. 20 5 20
REVIEW QUESTION 21 How does the science of fire relate to energy, forms of ignition, and modes of combustion? 5 21 Learning Objective 2 22 Describe the impact of thermal energy on heat, temperature, and heat transfer. 5 22 Thermal energy (heat) is the energy element in both fire models. 23 5 23 You should understand the relationship between heat and temperature. 24 5 24
There are several sources of thermal energy you should recognize. 25 5 25 Understanding the concept of heat transfer can help in several ways. 26 5 26 The concept of transfer rate is influenced by several factors. 27 5 27 Conduction is the transfer of heat through and between solids. 28 5 28
Convection is the transfer of thermal energy by circulation or movement of fluid (liquid or gas). 29 5 29 Radiation is the transmission of energy as an electromagnetic wave, without an intervening medium. 30 5 30 REVIEW QUESTION 31 What impact does thermal energy have on heat, temperature, and heat transfer? 5 31 Learning Objective 3 32 Recognize the physical states of fuel. 5 32
Fuel is the material or substance oxidized or burned in combustion. 33 5 33 The chemical content of fuel influences heat of combustion and heat release rate. 34 5 34 Gaseous fuel can be the most dangerous of all fuel types. 35 5 35 The properties of liquid fuel are important to understand. 36 5 36
Vaporization is the transformation of a liquid to a vapor or gaseous state. 37 5 37 Solubility is a factor to consider regarding liquid fuels. 38 5 38 Density is also a factor to consider regarding liquid fuels. 39 5 39 The properties of solid fuel influence the process of pyrolysis. 40 5 40
REVIEW QUESTION 41 What are the physical states that fuel can be found in? 5 41 Learning Objective 4 42 Explain the relationship between oxygen and life safety. 5 42 Oxygen is the primary oxidizing agent present at most fires. 43 5 43 Combustion occurs after a fuel has been converted to a gaseous state and mixed with an oxidizer in proper ratio. 44 5 44
REVIEW QUESTION 45 How do oxygen and life safety relate to one another? 5 45 Learning Objective 5 46 Identify the products of self- sustained chemical reactions. 5 46 Self-sustained chemical reactions create several products. 47 5 47 REVIEW QUESTION 48 What products of self-sustained chemical reactions combine to make flammable and toxic substances? 5 48
Learning Objective 6 49 Explain the factors that affect fire development. 5 49 Learning Objective 7 50 Describe the stages of fire development. 5 50 The stages of fire development occur in both unconfined and confined fires. 51 Click image to play Traditional Lab development Courtesy of Dan Madrzykowski, NIST (Cont.) 5 51 The stages of fire development occur in both unconfined and confined fires. 52 Click image to play Actual Real world development Courtesy of Dan Madrzykowski, NIST 5 52
There are several factors that will affect fire development. 53 (Cont.) 5 53 There are several factors that will affect fire development. 54 (Cont.) 5 54 There are several factors that will affect fire development. 55 (Cont.) 5 55 There are several factors that will affect fire development. 56 5 56
REVIEW QUESTION 57 What different factors can impact fire development? 5 57 The incipient stage starts when the elements of the fire triangle come together and combustion begins. 58 Courtesy of Dan Madrzykowski, NIST 5 58 The growth stage occurs as the fire transitions and is influenced by air in the compartment. 59 Courtesy of Dan Madrzykowski, NIST 5 59 Thermal layering can also occur during the growth stage. 60 5 60
Isolated flames and rapid transitions may also be a part of the growth stage. 61 Courtesy of Dan Madrzykowski, NIST 5 61 The fully developed stage occurs when all combustible materials are burning. 62 Courtesy of Dan Madrzykowski, NIST 5 62 The decay stage brings combustion to a complete stop through two means. 63 Courtesy of Dan Madrzykowski, NIST 5 63 REVIEW QUESTION 64 What are the stages of fire development? 5 64
Learning Objective 8 65 Recognize signs, causes, and effects of rapid fire development. 5 65 Rapid fire development is responsible for numerous deaths and injuries. 66 5 66 Flashover occurs when combustible materials in a compartment ignite almost simultaneously. 67 5 67 There are several common elements in flashover to be aware of. 68 5 68
Progression to a flashover is determined by two factors. 69 5 69 Firefighters should be aware of several flashover indicators. 70 5 70 Backdraft is a change in ventilation that results in explosively rapid combustion of flammable gases. 71 Courtesy of Bob Esposito 5 71 Firefighters should know about several backdraft indicators as well. 72 5 72
Backdraft effects vary depending on several factors and will not always occur immediately after the opening is made. 73 5 73 A smoke explosion may occur before or after the decay stage as unburned fuel gases contact an ignition source. 74 5 74 REVIEW QUESTION 75 What are the signs and causes of a backdraft? 5 75 Learning Objective 9 76 Describe the methods through which fire fighting operations can influence fire behavior. 5 76
Firefighters can influence fire behavior through temperature reduction. 77 5 77 Firefighters can influence fire behavior through fuel removal. 78 5 78 Oxygen exclusion reduces a fire s growth and may extinguish it over time. 79 5 79 Chemical flame inhibition uses agents to interrupt the combustion reaction. 80 5 80
Unplanned ventilation may occur before or after suppression operations start. 81 (Cont.) 5 81 WARNING 82 Wind driven conditions can occur in any type of structure. Wind speeds as low as 10 mph (16 kph) can create wind-driven conditions. 5 82 Unplanned ventilation may occur before or after suppression operations start. 83 5 83 Tactical ventilation is planned, systematic, and coordinated. 84 5 84
WARNING 85 Even coordinated tactical ventilation increases the combustion rate in ventilation controlled fires. 5 85 REVIEW QUESTION 86 How can fire fighting operations impact fire behavior? 5 86 Summary 87 You need to understand the combustion process, how fire behaves, and how to select appropriate extinguishing agents. Understanding fire behavior can help you recognize developing fire conditions and respond safely to mitigate hazards present in the fire environment. 5 87