Chapter 14

© 2009 Delmar, Cengage Learning

Vehicle Fires

Chapter 14


Objectives

• Describe the safety precautions that must be taken before starting the investigation

• Describe the fuel and electrical systems of most common vehicles

• Describe the potential heat sources and fuels available in most vehicles today

• Describe the potential for arson and which indicators may point to an incendiary nature of the fire


Case Study

• Student had no feeling below arms• Family obtained used car that could be operated

by hand controls• Mother noticed burning smell when son returned

from school and found that he suffered burns to his back

• Investigation of vehicle found seat heater had malfunctioned, causing burns


Case Study (cont’d.)

Figure 14-1 Front seat driver’s side showing heat damage of seatfabric.

Figure 14-2 The heating element that was located directly behind fabric on the seat’s upright.


Introduction

• Vehicle fires are some of the most confusing fires to work

• Investigators need to do fire scene reconstruction – Work the scene from the least damage to the most

damage

• Passenger vehicle today is an extremely complex device

• 278,000 vehicle fires occurred in 2006


Safety and Initial Examination

• All precautions should be taken to protect yourself and others from injury

• Materials in modern vehicles contain numerous toxic fumes that are released from burning components – Range from hydrogen cyanide to carbon monoxide– Off-gassing: refers to vapors or gases that were

absorbed by fabric, carpet, and so forth during a fire and then released after the fire was extinguished


Safety and Initial Examination (cont’d.)

• First responder investigator should not take for granted that the initial fire crews have secured the vehicle

• Airbag deployment is a huge area of concern– Bags can inflate in 1/20th of a second

• Not recommended to crawl under the vehicle• Always be aware of sharp edges and broken

glass – Wear protective equipment at all times


Type of Vehicle and Ignitable Fuels

• Basic makeup of various vehicles is the same– Framework, wheels, interior, and so forth


Diesel Engines

• Diesel engines operate on a compressed combustion chamber

• Diesel fuel is a combustible liquid with a flash point above 100° F

• Fuel is stored in a sealed tank and is pumped from a fuel pump through lines and filters

• Failure of the system at any given point may be a possible point of fuel release in some vehicle fires


Gasoline Engines

• Gasoline is more volatile and has a lower ignition temperature– Causes concern about it being the first fuel ignited

• Gasoline engines operate on flammable liquids that have a flash point of less than 100°F– Lack of maintenance or worn and loose parts can

cause the fuel to be sprayed • Possible cause for the spread of the fire in the event it

came into contact with an ignition source


Other Liquids

• Transmission fluid, windshield washer solvents, ethylene glycol, motor oil, brake fluids, and other hydraulic fluids – May ignite under extreme conditions, either

contributing to or causing a fire


Hot Surfaces

• Manifold, catalytic converter, and exhaust pipe operate at sufficient temperatures to ignite a wide range of fuels

• Leaking brake fluid is most often the first fuel ignited when it leaks onto a hot surface

• Gasoline will not usually ignite when sprayed onto a hot surface– Many variables such as ventilation or humidity can

influence this


Electrical Systems

• Most vehicles operate on a 12-volt direct current (DC) system – Secondary wiring can come into play in fires from

wear and tear and misuse– Resistance heating can cause the insulation around

the wire to break down or melt

• Hybrids bring a whole new realm to the investigation of vehicle fires – Voltage in hybrid vehicles can reach more than 300

volts of alternating current (AC)


Hybrid Vehicles

• Combine an internal combustion gasoline engine with an electric, battery-powered motor

• Contain a high-voltage NI-MH battery pack • In a series hybrid, the gasoline engine will

automatically stop and start • In a parallel system, the electric motor runs in

conjunction with the gasoline engine • If the vehicle is partially or more submerged, do

not touch any high-voltage components


Other Forms of Heat

• Vehicle’s heater, fans, and wires attached need to be looked at

• Properly operating catalytic converter, located on the underside of the vehicle, can reach temperatures of more than 700° F

• Turbo chargers create tremendous amounts of heat and may be a source of ignition

• Smoking-related incidents can be difficult to find


How Did the Vehicle Burn and Why?

• If the vehicle was kept in clean and running condition and there is a fire, it may have been arson– For the purpose of insurance fraud

• Scene first needs to be photographed from all sides

• Photos of the area from the vehicle looking outward need to be taken– Particularly important when a stolen vehicle is found


What Does the Exterior of the Vehicle Tell You?

• Extent of damage may show direction of fire travel

• Burn marks or demarcation lines may show path of travel

• Patterns left behind will show the direction from where the fire began

• Fire burns typically up and out– V pattern as in structure fire


What Does the Exterior of the Vehicle Tell You? (cont’d.)

• VIN contains information about the vehicle, such as year, make, model, engine, and paint color

• One interesting facet to look at is the vehicle’s glass– Fire will cause long cracks on the front windshield

• Look at the tires remaining on the vehicle– May show direction of flame


Inside the Vehicle

• Look at the glove box• Did the owner leave the keys in the vehicle?• Most of the interior of the vehicle is combustible

– Composed of plastics or fabric

• Hood will show burn patterns from the heat and flame impingement if the fire was in the engine compartment


Motor Homes

• Motor home contains components of a vehicle combined with the combustibles and heat source of a structure

• Motor homes are unusual and must be investigated with care – May contain liquid propane gas for heat and fuel for

the cooking equipment – May have a built-in generator that may use a

flammable or combustible liquid


Boats

• Not much different from a vehicle or a motor home

• Gasoline can collect in lowest part of hull• Unique situations in boat fires

– Possibility that the boat sank

• With inboard motors, you should look into the engine compartment

• Area where the boat was moored should be closely examined


Summary

• Work the fires from the exterior to the interior and from the least damaged to most damaged

• Scene needs to be documented and photographed on all sides

• Investigator needs to sift debris to find evidence that will aid in using a scientific methodology

• Both motor homes and boats have the same characteristics as other motorized vehicles

Chapter 14

Technology

cengage learning

type of vehicle

vehicle fireschapter

vehicle lookingou

introduction vehicle

hybrid vehicles

gasoline engines gasoline

mostdamage passenger