Chapter 6 Fire Patterns

Question 1

A fire pattern is _____________

Answer 1

The visible or measurable physical changes or identifiable shapes formed by a fire effect or group of fire effects.

Question 2

___________are the observable or measurable changes in or on a material as a result of exposure to the fire.

Answer 2

Fire Effects

Question 3

The mass loss of material is often used as an indication of

Answer 3

the duration and intensity of the fire.

Question 4

The rate of mass loss is generally dependent on

Answer 4

the heat flux to the material surface

Fire growth rate

rate of heat release of the material itself

Question 5

When exposed to elevated temperatures, wood undergoes pyrolysis, a chemical decomposition that drives off

Answer 5

gases

water vapor

various pyrolysis products as smoke.
(the solid residue that remains is mainly carbon)

Question 6

The rate of charring of wood varies widely depending upon variables, including:

Answer 6

Rate and duration of heating

Ventilation effects

Surface to mass ratio

Type of wood

Moisture content

Question 7

The rate of charring and burning of wood in general has no relation to its age once

Answer 7

the wood has been dried.

Question 8

No specific time of burning can be determined based solely on

Answer 8

depth on char.

Question 9

Analysis of the depth of charring is more reliable for evaluating_____, rather than for establishment of specific burn times or intensity of heat from adjacent burning materials.

Answer 9

fire spread

Question 10

________ is characterized by the loss of surface material resulting in cracking, breaking, and chipping or in the formation of craters on concrete, masonry, rock, or brick.

Answer 10

Spalling

Question 11

_________ is the breakdown in surface tensile strength of material caused by changes in temperature, resulting in mechanical forces within the material.

Answer 11

Fire-related Spalling.

Question 12

A mechanism of spalling is the _____ or _______ of the surface while the rest of the mass expands or contracts at a different rate.

Answer 12

expansion or contraction

Question 13

Another factor in the spalling of concrete is loading and stress in the material at the time of the fire. Because these high-stress areas may not be related to the fire location

Answer 13

spalling of concrete on the underside of ceilings may not be directly over the origin of the fire.

Question 14

_________ is the basic chemical process associated with combustion.

Answer 14

Oxidation

Question 15

The melting of certain metals may not always be caused by fire temperatures higher than the metals’ stated melting point; it may be caused by

Answer 15

alloying.

Alloying refers to the mixing of, generally , two or more metals in which one or more of the metals is in a liquefied state, resulting in an alloy.

Question 16

Nearly all materials ____ when heated.

Answer 16

expand

Question 17

Bending and buckling of steel beams and columns occurs when the steel temperature exceeds approximately

Answer 17

900 degrees

Question 18

_________ is a phenomenon whereby the soot particulate forms identifiable patterns on such surfaces of the smoke alarm as the internal and external surfaces of the smoke alarm cover near the edges of the “horn” sound oulets, the edges of and “horn outlets of the interior “horn” enclosures.

Answer 18

Enhanced Soot deposition on smoke alarms

Acoustic Soot Agglomeration

(there will be a buildup of soot around the alarm horn)

Question 19

A ______ is a distinct and visible fire effect generally apparent on non-combustible surfaces after combustible layers have been burned away.

Answer 19

Clean Burn

Clean burn patterns produced by burning away of soot can be produced by direct flame contact or intense radiated heat. The carbon will be oxidized to gases and disappear from the surface.

Question 20

________ of gypsum wallboard involves driving the free and chemically bound water out of the gypsum as well as other chemical and physical changes to the gypsum component itself.

Answer 20

Calcination

Question 21

Calcination involves a chemical change of the gypsum to another mineral,______

Answer 21

anhydrite

Question 22

What causes window glass to break in a fire?

Answer 22

If a pane of glass is mounted in a frame that protects the edges of the glass from radiated heat of fire, a temperature difference occurs between the unprotected portion of glass and the protected edge.

The temperature difference can cause cracks that start at the edge of the glass.