Fire and explosions

Question 1

What are fire and explosions?

Answer 1

Combustion; chemical reaction

Question 2

Combustion is the reaction of what with what?

Answer 2

A fuel with oxygen

Question 3

What does complete combustion create?

Answer 3

Carbon dioxide, water, and energy

Question 4

What is a chemical reaction that releases energy?

Answer 4

Exothermic

Question 5

What is a reaction that requires the input of energy in order to take place?

Answer 5

Endothermic

Question 6

All combustion reactions are what reactions? (endothermic/exothermic)

Answer 6

Exothermic

Question 7

In order to start a reaction, what is required? - the name of input of some energy

Answer 7

Activation energy

Question 8

What two factors determine whether combustion results in fire or explosion?

Answer 8

(1) the nature of the fuel

(2) how close the oxygen and the fuel are to each other

Question 9

What are 4 elements in fire tetrahedron?

Answer 9

A source of heat, fuel, oxygen, chain reaction between the fire and the oxygen.

Question 10

What do fire investigators need to know about fire?

Answer 10

what a fire is, how fire can be started, types of fires, how to investigate fire scenes, fire residues and its origin, role of the forensic science laboratory

Question 11

What is the lowest temperature that will allow a liquid to produce a flammable vapor?

Answer 11

Flash point

Question 12

What is the minimum temperature to which a substance must be heated before it will sustain a burn?

Answer 12

Ignition temperature

Question 13

What has higher temperature? (Flash point/Ignition temperature)

Answer 13

Ignition temperature

Question 14

When does smoke occur?

Answer 14

When there is incomplete combustion

Question 15

What is smoke made up of?

Answer 15

carbon particles and unburned and partially burned gasses

Question 16

What is a flashback?

Answer 16

Fire burns with a limited supply of oxygen is suddenly ventilated, resulting in an explosive fire

Question 17

What are accelerants

Answer 17

Fuels that are easily vaporized, support combustion, and are highly exothermic

Question 18

When are accelerants used?

Answer 18

to make a fire burn quickly

Question 19

What are the types of fires?

Answer 19

Natural; Accidental; Deliberate

Question 20

What are natural fires?

Answer 20

Chief natural cause for a fire is lighting

Question 21

What are accidental fires?

Answer 21

May arise from a number of different sources and may be difficult to distinguish from deliberate fires

Question 22

What is the most important evidence?

Answer 22

Point of origin, cause of fire

Question 23

Generally, where can investigator find the most intense burning and damage?

Answer 23

Point of origin

Question 24

What are char patterns?

Answer 24

created by very hot fires that burn very quickly and move fast along its path; so that there can be sharp lines between what is burned and what isn’t.

Question 25

What are V-patterns?

Answer 25

Fire burns up, in a V-shaped pattern, so a fire that starts at an outlet against a wall leaves a char pattern that points to the origin.

Question 26

What are Heat Shadows

Answer 26

Occur when heavy furniture shields part of a wall; can help determine the origin point.

Question 27

What is Chimney effect?

Answer 27

Since fire burns upward, there can be a chimney effect where the fire ignites at a point, the super heated gases rise upward and form a fireball, which continues straight up to burn a hole in the ceiling.

Question 28

What must you find to identify the cause of fire? (3)

Answer 28

1. fuel 2. source of heat 3. how the two came together

Question 29

Where should investigators focus on when finding a trace evidence?

Answer 29

Points of entry, exil and origin

Question 30

Where will acceleants most often be found?

Answer 30

at point of origin or along fire trails

Question 31

What should you use to detect accelerant?

Answer 31

Hydrocarbon-sniffing dog

Question 32

What is a less sensitive method to detect accelerant?

Answer 32

stripped-down gas chromatograph with a gas sensor

Question 33

What kind of container must be used for packaging fire scene evidence? why?

Answer 33

Airtight; it prevents evaporation and contamination

Question 34

What kind of container is used to package fire scene evidence?

Answer 34

Metal; airtight, rugged, easy to use

Question 35

What signs indicate non-accidental fire?

Answer 35

odors, furnishing, clothing, locked windows, blocked doors, two or more points of origin, narrow V-pattern, floor charred, trailers

Question 36

What is furnishing?

Answer 36

Removal of personal objects and valuables

Question 37

What are 6 common motives for arson?

Answer 37

Crime concealment, revenge or spite, monetary gain, malicious vandalism, mentally disturbed, serial arson

Question 38

What kind of motive for arson accounts for the largest percentage or arson fires?

Answer 38

Malicious Vandalism.

Question 39

What is Monetary gain?

Answer 39

Arson-for-profit fires are set to burn a building, vehicle, or some other object in order to gain profit from the fire.

Question 40

What is the bomb seat?

Answer 40

origin of the explosion

Question 41

What is blast pressure?

Answer 41

escaping gases that can travel as much as 8,000 miles per hour

Question 42

What results in negative pressure?

Answer 42

Partial vacuum that is created in wake of blast wave, which causes air to rush back toward the bomb seat.

Question 43

What is the most destructive part of the explosion?

Answer 43

negative pressure phase

Question 44

What are fragmentation effects?

Answer 44

shattered bombs result in pieces that are propelled way from the bomb seat with great force

Question 45

What are thermal effects?

Answer 45

large ball or fire or flash produced at bomb seat

Question 46

What is the least damaging effect from an explosion?

Answer 46

thermal effects