Chapter 3 Chemical Fires and Explosions

Question 1

What are the four categories of explosions?

Answer 1

Chemical (including explosible dusts), mechanical, electrical and nuclear

Question 2

What are the two types of explosive mixtures and what is the difference?

Answer 2

Diffusive (chemical mixes with air)and Condensed-phase (explosive oxidizes within itself)

Question 3

What impacts diffuse-phase explosions

Answer 3

Type of fuel, concentration, ignition mechanism and degree of confinement

Question 4

If LP gas is a possible cause of a chemical explosion, what must be investigated?

Answer 4

Recent repair work, appliance installations, or any other sources of furtive gas

Question 5

Which type of fuel gas can detonate under some conditions

Answer 5

Acetylene

Question 6

With the exception of natural gas, the vapor densities of most flammable gases in comparison to air are?

Answer 6

Heavier than air

Question 7

The propagation of vapors from a spill or flammable liquid are affected by?

Answer 7

Type of fuel, present of draft conditions or other air movement.

Question 8

What is necessary for a pressure effect to be produced in a deflagration

Answer 8

confinement of reaction in a rigid container or structure

Question 9

What two factors extend the explosive range?

Answer 9

Heat and pressurization

Question 10

UCVE

Answer 10

Unconfined vapor cloud explosion

Question 11

What are the resulting pressures achieved from a backdraft?

Answer 11

.5 to 1.5psi

Question 12

What is the major difference between gas/air deflagrations and dust explosions?

Answer 12

Dust on surfaces can be agitated during the initial phase and will propagate the deflagration much longer

Question 13

In order for an ignition source to ignite a flammable mixture what must be present

Answer 13

The fuel mixture must be present in combustible concentrations in the immediate area of the heat source.

Question 14

What do condensed-phase explosions involve

Answer 14

Liquid or gel explosives in which the fuel and oxidized are mechanically mixed or is able to undergo extremely rapid conversion

Question 15

What do most high explosives require?

Answer 15

An initiating mechanical shock that triggers a cascade effect of reactions throughout the reaction volume

Question 16

Brisance

Answer 16

Shattering power

Question 17

What compounds form the most common types of explosive chemicals

Answer 17

Nitrogen compounds

Question 18

What is one of the most widely used improvised explosive materials

Answer 18

TATP (Tri-acetone, tri-peroxide) made with hair polish remover, hair bleach, and batteries

Question 19

Contents of hobby fuse

Answer 19

pyrotechnic powder wrapped in windings of fine string and coated with a nitrocellulose lacquer

Question 20

Contents of safety fuse

Answer 20

Finely ground black powder supported by wrappings of string, tar and plastic

Question 21

Contents of igniter cord

Answer 21

Perchlorate-based incendiary filler with a multiple spiral wrap of fine, nickel-chrome iron wire

Question 22

Elements of a firing train

Answer 22

initial heat source, fuse, blasting cap, booster, and main charge

Question 23

Mechanical explosion

Answer 23

container or vessel that bursts when the internal gas or liquid pressures exceed the tensile strength of the container