Download Chemical Chain Reaction

Fire Loss Control - Basic Elements
Mgt. &
Maint.
Building
Construction
Ignition
Sources
OCCUPANCY
Code
Enforcement
• Jail
• Fireworks Factory
Fuel
Sources
• Day Care
Response
On &
Offsite
FP 3 - 1
Detection &
Suppression
Combustion
Products
NFPA 921 Fire Definition
 A rapid oxidation process with the
evolution of light & heat in varying
intensities.
FP 3 - 2
Oxidation as a Chemical Reaction
 Breaks down the fuel & oxidizer,
allowing the atoms to recombine in the
form of compounds different from those
from which was started:
 Reactants
- fuel & oxidizers
 Products - new components
FP 3 - 3
Fire Definition
 A rapid oxidation process that generates
heat.
 Self-sustaining
 Exothermic
 Smoke
FP 3 - 4
producing
Fire Definition
 Rapid, self-sustaining oxidizing process
that evolves heat, light & smoke in
varying quantities
FP 3 - 5
Fire vs. Combustion
Fire
 Unplanned
 Uncontrolled
FP 3 - 6
Combustion
 Level of control
 Fuel & oxidizers are
regulated
 High efficiency
Fire Triangle
FP 3 - 7
Fuel (stored energy)
 Wood, paper
 Hydrocarbons (methane, butane,
propane)
 Petroleum products
FP 3 - 8
Oxygen & Oxidizers
Unlocks the stored energy
 Oxygen
 Chlorine
 Nitrates
 Chlorates
 Concentrated nitric acid
FP 3 - 9
Sources of Heat Energy





FP 3 - 10
Chemical
Electrical
Mechanical
Nuclear
Decaying organic material (oily
rags - spontaneous combustion)
Fire Tetrahedron
FP 3 - 11
Chemical Chain Reaction
FP 3 - 12
Combustion Chain Reactions
FP 3 - 13
Heat Transfer
 Conduction
 Radiation
 Convection
FP 3 - 14
Convection / Conduction
FP 3 - 15
Radiation
FP 3 - 16
Fire Extinguishment Theory
 Heat removal (water / cooling)
 Fuel removal (sometimes partial)
 Oxygen removal
 Stop chemical chain reaction
FP 3 - 17
Definitions
 Upper Flammable Limit - The largest
concentration of gas or vapor in air
which can catch fire or explode when
exposed to a source of ignition.
 Lower Flammable Limit - The smallest
concentration of gas or vapor in air
which can catch fire or explode when
exposed to a source of ignition.
FP 3 - 18
FLAMMABLE LIMITS
6.7%
Lower
Flammable Limit
(LFL)
36%
Upper
Flammable Limit
(UFL)
LEL Meter
reads 0 - 100% of
Too Lean Region
Too Rich
25%
0%
Fire
Range
50%
Percent Gas - Vapor in Air
Methyl Alcohol
FP 3 - 19
75%
100%
FLAMMABLE LIMITS
1.5%
Lower
Flammable Limit
(LFL)
6.7%
Upper
Flammable Limit
(UFL)
LEL Meter reads 0
- 100% of Too
Lean Region
Too Rich
0%
25%
Fire
Range
50%
Percent Gas - Vapor in Air
Pentane
FP 3 - 20
75%
100%
LEL / UEL
0
HYDROGEN
ACETONE
BENZENE
ETHYLENE
10
20
FP 3 - 21
40
50
4.1
2.5
1.3
7.9
2.7
36.0
16.0
5.3
60
70
80
90
74.2
13.0
AMMONIA
METHANE
30
15.0
25.0
100
LEAN REGION
LEL
UEL
RICH REGION
TOO MUCH
AIR
EXPLOSIVE
TOO MUCH
GAS
FP 3 - 22
Liquid Fuels
Key Definitions
 Evaporation
 Vapor Pressure - The pressure exerted by a
volatile liquid at a specified temperature.
 Flash Point - The lowest temperature at which
a liquid gives off enough vapor to form an
ignitable mixture with air and produce a flame
when a source of ignition is present.
FP 3 - 23
Liquid Fuels
 Ignition Temperature -The minimum
temperature to which a fuel in air must be
heated in order to start self sustained
combustion independent of the heating source.
 Auto-ignition Temperature - The lowest
temperature that a flammable gas-air or
vapor-air mixture will ignite from its own heat
source or contact with a hot surface, without
spark or flame.
FP 3 - 24
Classes of Flammable Liquids
 Class IA - flashpoint below 73oF &
boiling points below 100oF
 Class IB - flashpoint below 75oF &
boiling point at or above 100oF
 Class IC - flashpoint at or above 73oF &
below 100oF
FP 3 - 25
Combustible Liquids
 Class II - flashpoint at or above 100oF &
below 140oF
 Class IIIA - flashpoint at or above 140oF
& below 200oF
 Class IIIB - flashpoint at or above 200oF
FP 3 - 26
Solid Fuels
Key Definitions
 Pyrolysis - the chemical decomposition of a
substance through the action of heat
 Piloted ignition temperature - heat level
required to form a gas that will ignite when
exposed to a spark
 Auto-ignition temperature - The lowest
temperature that a flammable gas-air or
vapor-air mixture will ignite from its own heat
source or contact with a hot surface, without
spark or flame.
FP 3 - 27
Classes of Fire
 A - Ordinary combustibles
 B - Flammable liquids
 C - Energized electrical equipment
 D - Combustible metals
 K - Cooking appliances involving
combustible cooking media (vegetable or
animal oils & fats)
FP 3 - 28