Fires and explosions

Question 1

What is the activation energy of a fire?

Answer 1

The energy required to elevate fuel and oxygen molecules into an excited state to undergo reactions

Question 2

What is the ignition temperature of a fire?

Answer 2

The temperature required for combustion to begin

Question 3

What is the flash point of a fire?

Answer 3

The temperature required to convert enough of the fuel into a vapor for combustion

Question 4

What is the flame point of a fire?

Answer 4

The temperature required to sustain a fire

Question 5

What features of accelerants allow them to support combustion?

Answer 5

Easily vaporized and burnt easily

Question 6

What are the three types of fires?

Answer 6

Natural, accidental and deliberate

Question 7

What is self ignition?

Answer 7

Spontaneous combustion leading to lighting self on fire

Question 8

What is direct ignition

Answer 8

The direct application of sparks of flames to fuel to light a fire

Question 9

What is indicated about the point of origin by low burning of fire?

Answer 9

Fires generally start in a low area of a building to do more damage

Question 10

What is indicated about the point of origin by V-patterns of smoke?

Answer 10

Origin is near a wall or corner, leaving smoke damage in the v-shape

Question 11

What is indicated about a fire by the charring of wood?

Answer 11

Depth of the charring depends on heat intensity therefore more charring indicates closer proximity to fire

Question 12

What is indicated about a fire from the spalling of plaster or concrete?

Answer 12

Occurs where the heat is most intense, surface destruction or concrete explosion from trapped moisture

Question 13

What is indicated about a fire from material distortion?

Answer 13

Metal and glass distorts under high heat and therefore can indicate proximity and temperature of the fire

Question 14

What is indicated about a soot staining by the soot staining?

Answer 14

Indicates fire origin and direction of travel

Question 15

What are indications of arson?

Answer 15

Presence of accelerant near origin, elimination of natural and accidental causes, multiple points of origin and fire trails from accelerant being poured in a trail

Question 16

What methods can be used to detect accelerant?

Answer 16

Dogs trained to sniff out hydrocarbons, gas chromatography to detect hydrocarbon

Question 17

What is commonly used to package accelerant residue?

Answer 17

Air tight containers including paint cans and glass jars

Question 18

How are hydrocarbons isolated in ignitable liquids?

Answer 18

Hydrocarbons are insoluble and therefore are easily extracted

Question 19

How are hydrocarbons isolated in partially burnt samples?

Answer 19

Most volatile compounds have evaporated and therefore remaining compounds with a high boiling point can be extracted

Question 20

How are hydrocarbons isolated in nearly completely burnt samples?

Answer 20

Nearly all the compounds have evaporated and therefore it is difficult to extract sufficient evidence

Question 21

What is involved in passive adsorption?

Answer 21

Placing a charcoal or synthetic material to adsorb the hydrocarbons with the sample and leaving overnight

Question 22

What is involved in active adsorption?

Answer 22

Charcoal or synthetic material to adsorb the hydrocarbons is placed in a tube and the sample is pumped through

Question 23

What is the blast pressure of an explosion?

Answer 23

The formation of a partial vacuum as compressed air from the explosion rushed back, creating a negative pressure phase

Question 24

What is the fragmentation effect of an explosion?

Answer 24

Propelling pieces with great force from the explosion, including shattered bomb or metal wrapped around bomb

Question 25

What is the thermal effect of an explosion?

Answer 25

The large ball of fire produced at the instant of detonation

Question 26

What is a low explosive?

Answer 26

Explosion with velocity less than 3280 fps where the oxygen and fuel is mixed

Question 27

What is a high explosive?

Answer 27

explosion with velocity greater than 3280 fps where a shock is required to break the bonds between oxygen and the fuel

Question 28

What type of explosive aims to push rather than shatter?

Answer 28

Low explosive

Question 29

What leads to a low order explosion, where the explosion occurs at less than optimal efficiency?

Answer 29

Using an old explosive, exposure to moisture and improper construction

Question 30

What is in explosive residue?

Answer 30

Undetonated explosive and exploded residue products