Chap 5 Flashcards
(105 cards)
1
Q
NIOSH
A
National institute of occupational safety and health
2
Q
What is the traditional mission of the fire service
A
Fighting fires in structures, vehicles, vessels, aircraft, , grassland/forests
3
Q
Combustion
A
A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of either a glow or flame
4
Q
Fire
A
A rapid oxidation process, which is a chemical reaction in varying intensities
5
Q
Heat
A
A form of energy characterized by vibration of molecules and caliber of initiating and supporting chemical changes
6
Q
Temperature
A
Measure of a materials ability to transfer heat energy to other objects
7
Q
Fuel
A
A material that will maintain combustion under specified environmental conditions
8
Q
Oxidizer
A
Any material that readily yields o2!or other oxidizing gas, or readily reacts to promote or initiate combustion of combustible materials
9
Q
Matter
A
Anything that occupies space and has mass
10
Q
Energy
A
Capacity to perform work
11
Q
Oxidation
A
Chemical process that occurs when a substance combines with an ozidizer
12
Q
Potential energy
A
Stored energy possessed by an object that can be released in the future to perform work once released
13
Q
Kinetic energy
A
The energy possessed by a body bc of its motion
14
Q
Firefighters should have a scientific understanding of
A
Combustion, fire, heat, and temp
15
Q
All fires involve a chemical reaction between
A
fuel and oxidizer
16
Q
What is physical science
A
The study of matter and energy, includes chemistry and physics
17
Q
A chem reaction occurs when a substance:
A
Changes from one type of matter into another
18
Q
Types of energy
A
Chemical,thermal,mechanical, electrical, light, nuclear, and sound
19
Q
Exothermic reaction
A
Chem reaction that releases thermal energy or heat
20
Q
Endothermic reaction
A
Absorbs thermal energy or heat
21
Q
Pyrolysis
A
Chem decomposition of a solid material by heating, precedes combustion
22
Q
Vaporization
A
Physical process that changes a liquid to a gas
23
Q
Ignition
A
Process of initiating self sustained combustion (NFPA 921)
24
Q
Piloted ignition
A
Movement when a mix of fuel and o2 encounters an external heat source with sufficient heat or thermal energy to start the combustion process
25
Auto ignition
Initiating of combustion by heat but without a spark or flame (NFPA 921)
26
True or False
| Combustion can occur with out fire?
True
27
Auro ignition temp
Lowest temp that a combustible material ignites in air w/o a spark or flame
(NFPA 921)
28
Fire triangle
Products necessary for combustion
Heat, o2,fuel
29
Fire tetrahedron
Elements/conditions necessary to have a fire.
Fuel, heat, O2 and self sustaining chem chain reaction
30
Passive agent
Materials that absorb heat but do not participate actively in the combustion process
31
What’s the most common passive agent
Drywall, gypsum board
32
Outside of structures what commonly acts as a passive agent
Vegetation
33
What are examples of non flaming combustion
Burning charcoal, smoldering wood or fabric
34
Carbon monoxide
Colorless, odorless gas
Headache, dizziness, weakness,confusion, nausea, unconsciousness, death
0.2 ppm can result in unconsciousness in 30 min
35
Formaldehyde
Colorless gas with a pungent irritating odor that is highly irritating to the nose.
50-100 ppm can cause severe irritation to the respiratory track and serious injury.
Can cause injury to skin
36
Hydrogen cyanide
Colorless, toxic, and flammable liquid below 79 F produced by combustion of nitrogen-bearing substances.
Chem asphyxiant that acts to prevent body from using o2
Commonly encountered in smoke
37
Nitrogen dioxide
Reddish-brown or yellowish-brown liquid, which is highly toxic and corrosive
38
Particulates
Small particles that can be inhaled and deposited in the mouth, trachea,or the lungs
39
Sulfur dioxide
Colorless gas with a choking or suffocating odor.
Toxic and corrosive, can irritate eyes and mucous membranes
40
What causes most fire deaths?
Toxic smoke
41
What is smoke
An aerosol comprised of gases, vapor, and solid particulates
42
Smoke is the product of
Incomplete combustion
43
True or false
| Carbon monoxide is the frequently identified as the cause of death of civilian and firefighter fatalities at a fire.
True
44
Where is hydrogen cyanide commonly used
Furniture and bedding
45
True or false
| Carbon dioxide is the product of complete combustion
True
46
What is the most common source of heat incombustion reactions
Chemical energy
47
Resistance heating
When electric current flows through a conductor, heat is produced
48
Overcurrent or overload
When the current flowing through a conductor exceeds its design limits
49
Arcing
An arc is a high temp luminous electric discharge across a gap or through a medium
50
Sparking
When an electric arc occurs , luminous particles can be formed and spatter away from the point of arcing
51
Heat flux
Measure of the rate of heat transfer to a surface
52
Conduction
Transfer of heat through or between solids that are in direct contact
53
Convection
Heat transfer by circulation within a medium such as a gas or a liquid
54
Radiation
Heat transfer by way of electromagnetic energy
55
What are the 3 ways heat is transferred from one body to another
Conduction
Convection
Radiation
56
Conduction occurs between
Solids
57
What 3 factors does heat transfer due to conduction depend on
Area being heated
Temp difference between the heat source and the the material being heated
Thermal conductivity of the heated material
58
Buoyant
The tendency or capacity to remain afloat in a liquid or rise in air or gas
59
As temp of heat source increases, radiant energy increases by a factor of the:
4th power
60
What is power
The rate at which energy is being transferred over time
61
Watt
One joule/sec
62
Upper layer
Buoyant layer of hot gases and smoke produced by a fire in a compartment
63
Reducing agent
The fuel that is being oxidized or burned during combustion
64
Heat of combustion
Total amount of thermal energy that could be generated by the combustion reaction if a fuel were completely burned
65
Heat release rate (HRR)
Total amount of heat released per unit time.
KW and MW of output
66
Vapor density
Weight of a givien volume of pure vapor or gas compared to the weight of an equal volume of dry air at same temp an pressure
67
Spec gravity
Mass of a substance compared to mass of an equal volume of water at a given temp
68
Vapor pressure
Measure of the tendency of a substance to evaporate
69
Flash point
Minimum temp at which a liquid gives off enough vapors to form an ignitable mixture with air near the liquids surface
70
Fire point
Temp at which a liquid fuel produces sufficient vapors to support combustion once fuel is ignited
71
Solubility
Degree to which a solid, liquid or gas dissolves in a solvent
72
Miscible
Materials that are capable of being mixed in all proportions
73
Hydrocarbon fuel
Petroleum based organic compound that contains only hydrogen and carbon
74
Polar solvents
Flammable liquids that have an attraction for water
75
Heated gases ________ and become less dense; when ________ They contract and become more dense
Expand, cooled
76
In order to burn liquids must be
Vaporized
77
True or false
| Liquids that are less dense than water or more difficult to extinguish using water as the sole extinguishing agent
True
78
Pyrolysis of wood begins at temperatures below
400 degrees F
79
Pyrolysis occurs faster or slower in plastics Than in wood
Faster
80
Gasoline
```
Water soluble:no
Specific gravity: 0.72
Flashpoint: (-45°F)-43°C
Auto ignition:(853°F) 456°C
Flammable range:1.4%- 7.4%
```
81
Diesel
```
Water soluble: no
Specific gravity: >1.00
Flashpoint: (125°F) 52°C
Auto ignition: (410°F) 210°C
Flammable range: 1.3%-6%
```
82
Ethanol
```
Water soluble: yes
Specific gravity: 0.78
Flashpoint (55°F) 13°C
Auto ignition (689°F) 363°C
Flammable range: 3.3% -19%
```
83
Methanol
```
Water soluble: yes
Specific gravity: 0.79
Flashpoint: (52°F) 11°C
Auto ignition: (864°F) 464°C
Flammable range 6%- 35.5%
```
84
Oxidizers are not combustible but they will
Support or enhance combustion
85
Upper flammable limit (UFL)
Upper limit at which a flammable gas or vapor will ignite
86
Free radicals
Molecular fragments that are highly reactive
87
Chemical flame inhibition
Extinguishment of a fire by interruption of the chemical chain reaction
88
Factors that affect Fire development
```
Fuel type
Availability and location of additional fuels
Compartment volume and ceiling height
Ventilation
Therm properties of the compartment
Ambient conditions
Fuel load
```
89
In a compartment Fire what is one of the most fundamental class a fuel characteristics influencing Fire development
Surface to mass ratio
90
What are factors that influence the ability and location of additional fuels in building configuration
```
Number of stories above or below ground
Compartmentation
Floor plan
Openings between floors
Continuous voids or concealed spaces
Barriers to fire spread
```
91
What are three ways ventilation occurs in a building
Constructed opening such as windows doors and passive ventilation devices
Leakage through cracks and other gaps in construction
Heating ventilating and air-conditioning systems
92
What two forms due room or compartment fires take
Fire controlled and ventilation controlled
93
Fuel controlled
A fire with adequate oxygen in which the heat release rate and growth rate are determined by characteristics of the fuel (NFPA 921)
94
Ventilation controlled
A fire with limited ventilation in which the heat release rate or growth is limited by the amount of oxygen available to the Fire (NFPA 921)
95
What are thermal properties of a compartment
Insulation
Heat reflectivity
Retention
96
Plume
Column of hot gases flames and smoke rising above the fire
97
Ceiling jet
A relatively thin layer of flowing hot gases that develops under horizontal surface as a result of Plume impingement and flowing gas being forced to move horizontally
98
Flash over
Rapid transition from the growth stage to the fully developed stage
99
During the flash over the volume of fire can increase from approximately ________of the rooms upper volume to filling the entire room and potentially extending out of any openings in the room
1/4-1/2
100
What are the four common elements of flashover
Transition in fire development
Rapidity
Compartment
Ignition of all exposed surfaces
101
What temperature does flashover typically occur at
1100°F
102
Flashover indicators
```
Building indicators
Smoke indicators
Airflow indicators
Heat indicators
Flame indicators
```
103
What does smoke look like for flashover conditions
Rapidly increasing volume, turbulence, darkening color, density, lowering of the hot gas level
104
Smoke indicators for Backdraft
Dense smoke, light colored or black becoming dense gray yellow, neutral plain rising and lowering similar to a pulsing or breathing movement
105
Backdraft can vary considerably depending on what factors
```
Volume of smoke
Degree of confinement
Pressure
Speed with which fuel and air are mixed
Location where ignition occurs
```
