Unit 1 Introduction to Fire Safety

Unit 1 Introduction to Fire Safety 1. Introduction 1.1 Importance of Fire Protection How could a fire effect an organization? NOTE: 40% of businesses hit by fire never reopen!!

1. Introduction 1.2 The Overall Fire Picture – NFPA 2009 • Every 22 seconds a fire department responds to a fire • 1,451,500 fires reported in the US • 3,320 deaths, 84% of which occur in residential homes • 16,705 civilian injuries occurred as a result of fires • $15.4 billion in direct losses

Introduction 1.3 Where Fires Occur • 49% were outside fires • 34% were structural fires (78.2% residential) • 17% were vehicle fires

1. Introduction 1.4 Causes of Residential Fires and Fire Deaths • Cooking • Heating • Arson

1. Introduction 1.5. NFPA Strategies • Residential properties • Public Fire Safety Education • Smoke Detectors and Escape Plan • Residential Sprinkler Systems • Fire safe home products • Special fire safety needs for high risk groups • Industrial properties

2. Chemistry & Physics of Fire 2.1 Nature of Heat Heat – A quantity of thermal energy - symbol is Q Units of Heat: BTU or Calorie Formula for heat: Q = MC∆T

2. Chemistry & Physics of Fire 2.2Specific Heat– The amount of heat required to raise one pound of a substance by 1ºF Units will be BTU/lb. ºF

2.Chemistry & Physics of Fire 2.3. Sensible Heat Change – the change in heat content of a material due to a temperature change only, no phase change. 2.4. Latent Heat Change – the change in heat content of a substance when it undergoes a phase change only, no temperature change. 2.5Heat of vaporization - is a kind of latent heat where liquid is converted to a gas (water fogs) 2.6Heat of fusion- is a kind of latent heat where solid is converted to a liquid

2. Chemistry & Physics of Fire 2.7Sublimation – Under certain circumstances some materials can change from the solid to the vapor state and visa versa, this usually occurs at pressures below atmospheric. 2.8Heat of Combustion is the amount of heat released when something burns Units are: BTU/LB Joules/g

3. Heat Transfer 3.1.Basic Principle: Heat energy always flows from hot to cold or from higher energy state to lower. Heat transfer implies a rate and the symbol is “I” I = Q/t Units: BTU/HR or J/sec.

3. Heat Transfer 3.2. Three major mechanisms of heat transfer • Conduction • Convection • Radiation 3.3 Heat Conduction 3.3.1 Heat transfer caused by molecules vibrating and colliding with other molecules transferring their kinetic energy

3. Heat Transfer 3.3.2. Factors that influence heat transfer via conduction: • Effects of distance upon heat transfer by conduction • Effects of cross sectional area on heat transfer • Effects of composition on heat transfer k - Coefficient of thermal conductivity units: BTU/hr ft ºF

3. Heat Transfer 3.3.3. Fourier’s Law of Heat Conduction Icd = k A T x Units: BTU/hr or Joules/sec 3.3.4. Heat Insulators

VS 2-3 CONDUCTION Vertical Horizontal Point-to-Point Transfer of Heat Energy from One Body to Another by a Heat-Conducting Medium

3. Heat Transfer 3.4. Heat Transfer by Convection 3.4.1Heat transfer because of the movement of a fluid (air) containing the heat 3.4.2. "Hot Air Rises" Natural Convection 3.4.3. The rate of heat transfer via convection is influenced by several factors

3. Heat Transfer 3.4.4. Convection Heat Transfer Coefficient Symbol & Units (h) BTU or Joules hr. ft2 ºF sec.m2ºC 3.4.5. Newton‘s Law of Cooling Formula: Icv = h AT

VS 2-4 CONVECTION Heat Transferred by Movement of Heated Liquids or Gases

3. Heat Transfer 3.5. Radiant Heat Transfer 3.5.1. Heat transfer via electromagnetic waves 3.5.2. Radiant heat transfer (emission) depends on: • The nature of the surface (emissivity e) • The distance between the radiation source and the object it strikes

VS 2-5 RADIATION Electromagnetic Waves Traveling Through Space Until They Reach a Solid Object

4. Combustion 4.1.Combustion: is a rapid oxidation accompanied by the emission of heat & light Oxidation - the chemical combination of an atom or molecule with oxygen and the chemical bonds contain energy.

4. Combustion 4.2. Key Principles of Combustion 4.2.1. Heat Energy necessary to initiate combustion 4.2.2. The reaction is self-sustaining once the ignition source is provided 4.2.3. For combustion to occur you must have a: a. fuel b. oxidizing agent c. heat to produce free radicals d. uninhibited free radical combination

VS 2-7 COMBUSTION The Fire Tetrahedron Reducing Agent (Fuel) Oxidizing Agent Heat Chemical Chain Reaction Oxidizing Agent Reducing Agent (Fuel) Heat Chemical Chain Reaction

VS 2-23 PRODUCTS OF COMBUSTION Carbon Monoxide Carbon Particles 4. SMOKE 3. FLAME 2. HEAT 1. LIGHT Sulfur Dioxide Hydrogen Cyanide Flammable Vapors Water Vapor Carbon Dioxide Fuel Oxygen Oxygen

4. Combustion 4.3. Products of Combustion 4.3.1. Heat 4.3.2. Smoke

4. Combustion 4.3. Products of Combustion 4.3.3. Fire Gases 4.3.4. Light - Flaming

5. Rates of Combustion 5.1 Flammable Gas 5.2 Flammable Liquid 5.3 Flammable Solid

6.Unique Combustion Phenomena 6.1. Explosion- is the rapid expansion of a gas that converts the potential energy of the gas to kinetic energy. 6.1.1. Sources of explosions in industry • Fuels (50%) • Flammable Liquid Vapors (12%) • Trapped Steam (7%) • Gas Leakage (6%) • Rupture of Pressurized Equipment (6%)

6. Unique Combustion Phenomena 6.2. Deflagration- is the burning of a gas or aerosol that is characterized by a combustion wave 6.3. Detonation - the burning of a gas or aerosol that is characterized by a shock wave

6. Unique Combustion Phenomena 6.4. Flashover 6.5 Backdraft 6.6. BLEVE

VS 2-18 FLASHOVER

VS 2-22b BACKDRAFT • • Low Oxygen • • High Heat • Smoldering Fire • • High fuel vapor • concentrations PRE-BACKDRAFT • Introduction of oxygen causes fire of explosive force BACKDRAFT

Unit 1 Introduction to Fire Safety