Fire Protection and Prevention. Physics and Chemistry of Fire Fire: The rapid oxidation of material...

Fire Protection and Fire Protection and PreventionPrevention

Physics and Chemistry of Physics and Chemistry of FireFire

FireFire: The rapid oxidation of material during : The rapid oxidation of material during which heat and light are emitted.which heat and light are emitted.

CombustionCombustion: an exothermic, self-: an exothermic, self-sustaining reaction involving a solid fuel, a sustaining reaction involving a solid fuel, a gaseous fuel or both. Most often the gaseous fuel or both. Most often the reaction is oxidation of a fuel by oxygen in reaction is oxidation of a fuel by oxygen in air.air.

Reducing AgentReducing Agent: Rubber, Wood, Plastic, : Rubber, Wood, Plastic, MethaneMethane

Oxidizing AgentOxidizing Agent: Oxygen, Fluorine, : Oxygen, Fluorine, Chlorine, HNOChlorine, HNO33, HF, H, HF, H22SOSO44

Ignition TemperatureIgnition Temperature: The minimum : The minimum temperature that each material must be temperature that each material must be reached for ignition to occur.reached for ignition to occur.

When some external source such as flame, When some external source such as flame, spark causes ignition, the process is called spark causes ignition, the process is called piloted ignitionpiloted ignition..

When there is no external source, the When there is no external source, the process is called process is called auto-ignitionauto-ignition, , spontaneous ignitionspontaneous ignition..

The piloted ignition temperature is lower The piloted ignition temperature is lower than the than the auto-ignition temperatureauto-ignition temperature..


Auto-ignition is often caused by heat Auto-ignition is often caused by heat buildup resulting from the oxidation of buildup resulting from the oxidation of organic material.organic material.

Bacteria and decomposition can contribute Bacteria and decomposition can contribute to the process in some material. The to the process in some material. The material ust reach the auto-ignition material ust reach the auto-ignition temperature and have enough oxygen for temperature and have enough oxygen for combustion.combustion.


The components necessary for fire or The components necessary for fire or combustion are (a) fuel, (b) a source of combustion are (a) fuel, (b) a source of oxygen, and (c) a source of heat or flame.oxygen, and (c) a source of heat or flame.


O2 Fuel

Heat

O2

FuelHeat

Chain ReactionFire Triangle Fire Pyramid

Method for controlling combustion and Method for controlling combustion and extinguishing fires:extinguishing fires:– Cool the fireCool the fire– Limit the oxygen supplyLimit the oxygen supply– Remove the fuelRemove the fuel– Inhibit the chain reactionInhibit the chain reaction


Ignition SourcesIgnition Sources ElectricElectric 2323 %% SmokingSmoking 1818 %% FrictionFriction 1010 %% Overheated materials Overheated materials 8 8 %% Hot surfacesHot surfaces 7 7 %% Burner flames Burner flames 7 7 %% Combustible sparksCombustible sparks 5 5 %% Auto-ignitionAuto-ignition 4 4 %% Cutting and WeldingCutting and Welding 4 4 %% Others (exposure, incendiarismOthers (exposure, incendiarism 1414

%%Mechanical sparks, chemical reactionMechanical sparks, chemical reactionmolten substance, static sparks, etc.)molten substance, static sparks, etc.)


Carbon monoxideCarbon monoxide Carbon monoxide forms when there is not enough Carbon monoxide forms when there is not enough

oxygen for complete combustion of the fuel.oxygen for complete combustion of the fuel. It is a major cause of death in fires because:It is a major cause of death in fires because:

– It is a very common product of combustionIt is a very common product of combustion– Relatively low concentrations can be lethal. A Relatively low concentrations can be lethal. A

concentration of 1.0% or higher can cause concentration of 1.0% or higher can cause death in 1 min or less.death in 1 min or less.

It attaches easily to the hemoglobin of the blood’s It attaches easily to the hemoglobin of the blood’s red cells. It does not easily release.red cells. It does not easily release.

Products of Combustion and Products of Combustion and Their HazardsTheir Hazards

Carbon dioxideCarbon dioxide Carbon dioxide can contribute to fire related Carbon dioxide can contribute to fire related

deaths.deaths. It is a common product of combustion in cell It is a common product of combustion in cell

metabolism of the body. A physiological response metabolism of the body. A physiological response to increasing carbon dioxide in the blood is to increasing carbon dioxide in the blood is increased respiration rate. When one exercises, increased respiration rate. When one exercises, the increase in carbon dioxide signals the body the increase in carbon dioxide signals the body that more oxygen is needed for the exercising that more oxygen is needed for the exercising muscles.muscles.

In a fire increased inhalation of other combustion In a fire increased inhalation of other combustion products creates greater danger for a person.products creates greater danger for a person.


Hydrogen Cyanide (HCN)Hydrogen Cyanide (HCN) HCN is an extremely toxic gas in HCN is an extremely toxic gas in

comparison to the CO. The amount of 100 comparison to the CO. The amount of 100 ppm in the air can cause the death within ppm in the air can cause the death within 30-60 min.30-60 min.

It occurs in the combustion of plastic, It occurs in the combustion of plastic, rubbish, wool, silk.rubbish, wool, silk.


Hydrogen Sulfide (HHydrogen Sulfide (H22S)S) Hydrogen sulfide is a colorless gas with an Hydrogen sulfide is a colorless gas with an

offensive stench and is said to smell like offensive stench and is said to smell like rotten eggs. It is the flammable gas.rotten eggs. It is the flammable gas.

It can be formed when there is not enough It can be formed when there is not enough oxygen for complete combustion of the oxygen for complete combustion of the sulfide compound materials (i.e., rubbish, sulfide compound materials (i.e., rubbish, carpet, wood, wool).carpet, wood, wool).

The concentration of 400-700 ppm. can The concentration of 400-700 ppm. can cause the death within 30-60 min.cause the death within 30-60 min.


Sulfur Dioxide (SOSulfur Dioxide (SO22)) Sulfur dioxide is a colorless gas with a Sulfur dioxide is a colorless gas with a

suffocating, choking odor. It is toxic to suffocating, choking odor. It is toxic to humans and concentrations as low as 8 humans and concentrations as low as 8 ppm will produce coughing.ppm will produce coughing.

It can occur from the complete combustion It can occur from the complete combustion of the sulfide compound materials.of the sulfide compound materials.

The concentration as low as 150 ppm. Can The concentration as low as 150 ppm. Can cause the death.cause the death.


Lack of OxygenLack of Oxygen A fire can consume much of oxygen available. As A fire can consume much of oxygen available. As

the normal 21 % oxygen content declines, the the normal 21 % oxygen content declines, the capability of the hemoglobin of the red cells to capability of the hemoglobin of the red cells to transport oxygen to body tissues decreases.transport oxygen to body tissues decreases.

Reduced oxygen supply can impair tissue Reduced oxygen supply can impair tissue function, and when muscles are affected, motor function, and when muscles are affected, motor performance go sown; when muscles are affected, performance go sown; when muscles are affected, motor performance can further impaired and motor performance can further impaired and mental processes reduced. If oxygen supply is mental processes reduced. If oxygen supply is reduced enough, unconsciousness results.reduced enough, unconsciousness results.


Fire Hazards of MaterialsFire Hazards of Materials

Flammable and Combustible LiquidsFlammable and Combustible Liquids Many of the common fuels, such as gasoline, Many of the common fuels, such as gasoline,

diesel fuel and heating oil, are in liquid form.diesel fuel and heating oil, are in liquid form. The The flash pointflash point of a liquid is the lowest of a liquid is the lowest

temperature at which the vapor pressure of temperature at which the vapor pressure of the liquid is just sufficient to produce a the liquid is just sufficient to produce a flammable mixture at the lowest limit of flammable mixture at the lowest limit of flammability.flammability.

The The fire pointfire point is he lowest temperature of a is he lowest temperature of a liquid in an open container at which vapors liquid in an open container at which vapors evolve fast enough to support continuous evolve fast enough to support continuous combustion.combustion.


Flammable and Combustible LiquidsFlammable and Combustible Liquids Vapor pressureVapor pressure is a property of a liquid in a is a property of a liquid in a

closed container. The atmosphere above the closed container. The atmosphere above the liquid is a mixture of air and vapors of the liquid. liquid is a mixture of air and vapors of the liquid. The portion of a vapor that will form in this The portion of a vapor that will form in this mixture is a function of the vapor pressure of the mixture is a function of the vapor pressure of the liquid.liquid.

The The boiling pointboiling point is the temperature at which the is the temperature at which the equilibrium vapor pressure of a liquid equals the equilibrium vapor pressure of a liquid equals the total pressure on the surface. It is the total pressure on the surface. It is the temperature that liquid boils under some temperature that liquid boils under some surrounding total pressure.surrounding total pressure.


Flammable and Combustible LiquidsFlammable and Combustible Liquids The mixture of fuel and standard air The mixture of fuel and standard air

necessary for combustion of fuel vapors necessary for combustion of fuel vapors must be within certain limits which is must be within certain limits which is the the flammable rangeflammable range..

The The lower flammable limitlower flammable limit (LFL) is the (LFL) is the minimum concentration of vapor-air below minimum concentration of vapor-air below which propagation of a flame will not occur which propagation of a flame will not occur in a presence of an ignition source.in a presence of an ignition source.

The The upper flammable limitupper flammable limit (UFL) is the (UFL) is the maximum vapor-air mixture above which maximum vapor-air mixture above which propagation will not occur.propagation will not occur.


Flammable gasFlammable gas Flammable gas must combine in appropriate Flammable gas must combine in appropriate

mixtures with air for combustion to occur mixtures with air for combustion to occur and they must be at or above their ignition and they must be at or above their ignition temperature to burn.temperature to burn.

Nonflammable gases are those that do not Nonflammable gases are those that do not burn in any concentration of air or oxygen. burn in any concentration of air or oxygen. Inert gases are those that will not support Inert gases are those that will not support combustion.combustion.

Some gases, called reactive gases, will react Some gases, called reactive gases, will react with other materials in processes other than with other materials in processes other than combustion (i.e., Chlorine – hydrogen).combustion (i.e., Chlorine – hydrogen).


WoodWood Wood and wood products, like pulp, paper Wood and wood products, like pulp, paper

and cardboard will burn.and cardboard will burn. During combustion, wood will char, that is, During combustion, wood will char, that is,

form a layer of partially burned material, form a layer of partially burned material, which insulates material below it from the which insulates material below it from the heat of combustion and slows the burning heat of combustion and slows the burning rate.rate.

Ignition temperatures vary significantly, Ignition temperatures vary significantly, depending on the moisture content, density depending on the moisture content, density and other factors.and other factors.


MetalsMetals Most metal will burn under certain Most metal will burn under certain

conditions.conditions. Small cross sections and fine particles will Small cross sections and fine particles will

burn more readily than thick solids.burn more readily than thick solids. Some metals are called combustible Some metals are called combustible

because they are relatively easy to ignite.because they are relatively easy to ignite. Combustible metals include magnesium, Combustible metals include magnesium,

titanium, zinc, sodium, lithium. titanium, zinc, sodium, lithium. Burning metals create special Burning metals create special

extinguishment problems.extinguishment problems.


Metals (cont.)Metals (cont.) Dumping water on a titanium fire may add to Dumping water on a titanium fire may add to

the fire. The water may break down into oxygen the fire. The water may break down into oxygen and hydrogen and the oxygen combining with and hydrogen and the oxygen combining with titanium and hydrogen becomes another fuel.titanium and hydrogen becomes another fuel.

Magnesium will burn in a carbon dioxide Magnesium will burn in a carbon dioxide atmosphere.atmosphere.

Aluminum, iron and steel will not burn easily Aluminum, iron and steel will not burn easily because they do not react with oxygen easily.because they do not react with oxygen easily.

Fine metal powders may ignite easily and Fine metal powders may ignite easily and explode.explode.


PlasticsPlastics There is a wide variety of plastics, some with There is a wide variety of plastics, some with

special additives to achieve particular properties.special additives to achieve particular properties. Plastic tends to have higher ignition Plastic tends to have higher ignition

temperatures than wood. Some have a rapid temperatures than wood. Some have a rapid flame spread rate and some are easily ignited flame spread rate and some are easily ignited and burn rapidly.and burn rapidly.

Many plastics produce dense black smoke during Many plastics produce dense black smoke during combustion, often due to the additives that combustion, often due to the additives that inhibit flammability.inhibit flammability.

Most plastics produce carbon monoxide and Most plastics produce carbon monoxide and many also produce other toxic gases.many also produce other toxic gases.

Fire Detection SystemFire Detection System

There are several kinds of detectors. There There are several kinds of detectors. There are detectors for heat, smoke, flame, and gas are detectors for heat, smoke, flame, and gas content.content.

Each type is suited for particular Each type is suited for particular applications, depending on the type of fire applications, depending on the type of fire that can occur and the kind of flammable and that can occur and the kind of flammable and combustible materials presetcombustible materials preset

Smoke

Fire

Heat

Detect Warn

Exit

Extinguish

Heat DetectorsHeat Detectors Fixed temperatureFixed temperature

– Thermo conductive detectorsThermo conductive detectors Fusible elements made from metal that melt at a Fusible elements made from metal that melt at a

preset temperature.preset temperature. Thermo conductive detectors: two continuous wires, Thermo conductive detectors: two continuous wires,

separate by insulation.separate by insulation.– Thermo expansion detectors: two metal forming Thermo expansion detectors: two metal forming

the strip each expand at different rates with the strip each expand at different rates with temperature increases, which cause the strip to temperature increases, which cause the strip to bend or the disk to snap to a different bend or the disk to snap to a different temperature.temperature.

Rate of riseRate of rise– The detectors response to fires that flame up The detectors response to fires that flame up

quickly (in general, 12 F/min) but do not react to quickly (in general, 12 F/min) but do not react to lower changes in ambient temperature.lower changes in ambient temperature.


Smoke DetectorsSmoke Detectors IonizationIonization

– The detectors contains contain a very small The detectors contains contain a very small quantity of radioactive material. They ionize quantity of radioactive material. They ionize the zone of air around the radioactive material, the zone of air around the radioactive material, making the air conductive. When smoke making the air conductive. When smoke particles enter the zone, thr conductivity particles enter the zone, thr conductivity decreases. They are most sensitive to small decreases. They are most sensitive to small smoke particles found in high energy, open smoke particles found in high energy, open flame fires.flame fires.

Photo electricityPhoto electricity– The detectors depend on a source and receiver The detectors depend on a source and receiver

of light. A beam is directed from the source to of light. A beam is directed from the source to the receiver or sensor.the receiver or sensor.


Four Classes of FiresFour Classes of Fires

Class AClass A Class "A" fires are Class "A" fires are the ordinary firesthe ordinary fires. These are fires . These are fires

which leave an ash. Wood, cloth, paper, leaves, and which leave an ash. Wood, cloth, paper, leaves, and rubbish are good examples of Class "A" fire rubbish are good examples of Class "A" fire materials. The fire in fire-place is a Class "A" fire.materials. The fire in fire-place is a Class "A" fire.

The best way to put out a Class "A" fire is to The best way to put out a Class "A" fire is to use use waterwater. .

Water helps to remove two of the three things which Water helps to remove two of the three things which are necessary before a Class "A" fire can burn.are necessary before a Class "A" fire can burn.– water cools the burning material down below the water cools the burning material down below the

temperature where it will burn. Second,temperature where it will burn. Second,– water coats the burning material and keeps oxygen away.water coats the burning material and keeps oxygen away.

Without oxygen. The fire quickly goes out.Without oxygen. The fire quickly goes out.


Class BClass B These are fires involving highly These are fires involving highly flammable liquidsflammable liquids

such as gasoline, oil, paint thinner and naphtha. such as gasoline, oil, paint thinner and naphtha. The starter fluid you pour on your outdoor The starter fluid you pour on your outdoor barbecue is a good example of a Class "B" fire.barbecue is a good example of a Class "B" fire.

These materials will usually burn at fairly low These materials will usually burn at fairly low temperatures. Because of this, the best way to temperatures. Because of this, the best way to put these fires out is to put these fires out is to remove the supply of remove the supply of oxygenoxygen. .

This is usually done by using a fire extinguisher This is usually done by using a fire extinguisher which blankets the fire with a layer of foam, or which blankets the fire with a layer of foam, or some other material which will not burn.some other material which will not burn.


Class CClass C These are fires involving These are fires involving electrical equipmentelectrical equipment. .

These can be very dangerous because you can These can be very dangerous because you can receive a serious electrical shock if you try to put receive a serious electrical shock if you try to put the fire out in the wrong way.the fire out in the wrong way.

Unless the Unless the electricity to the burning material has electricity to the burning material has been turned offbeen turned off an extinguisher which will not an extinguisher which will not conduct electricity ,must be used in order to put conduct electricity ,must be used in order to put these fires outthese fires out

You might find a Class "C" fire in a fuse box or an You might find a Class "C" fire in a fuse box or an electric motor. These fires should be put out with a electric motor. These fires should be put out with a Carbon dioxide fire extinguisher. Carbon dioxide fire extinguisher.

Don't use a water extinguisher. The electricity can Don't use a water extinguisher. The electricity can follow the stream of water right back to you, and follow the stream of water right back to you, and you could receive a serious or fatal shock.you could receive a serious or fatal shock.


Class DClass D These are fires involving These are fires involving flammable metalsflammable metals such such

as Magnesium, Lithium, Titanium, Sodium.as Magnesium, Lithium, Titanium, Sodium. These fires must be put out with dry chemicals fire These fires must be put out with dry chemicals fire

extinguishers which have been filled with special extinguishers which have been filled with special chemicals. chemicals.

These extinguishers help to These extinguishers help to keep oxygen awaykeep oxygen away from the burning materials.from the burning materials.

Many different kinds of metal will burn if they get Many different kinds of metal will burn if they get hot enough.hot enough.

Six types of Fire Six types of Fire extinguisherextinguisher

(1) Soda acid:

For only

Class "A" Fire

(2)Foam

For

Class "B"and "C" Fire

(3)Water

pressure

For only Class

"A" Fire

(4) Carbondioxide

Gas

For Class

"B" and "C" Fire

(5)Dry

chemical powder

For Class "B" and "C"

Fire"A" for experts

(6)Halogenat

e Non CFC agent

For Class"C" and "B"

Fire"A" for experts

Always test extinguisher before taking to fire.

Summary of the Notification of the Ministry of InteriorRe: Safety of Work Relating to Fire Prevention

in Workplaces in Regard for the Employee's Safety

Intention of the Law• To protect the employee from the dangers of

fire. • To prevent fire-incurred losses for employees

and for the workplace. • To prevent causes of fire, which affect the

general public.

Framework and Enforcement of the Law• To have effect on all industrial factories, hotels,

service industries, mining and transporting, etc.

1.1. The workplace or buildings used to store highly The workplace or buildings used to store highly explosive material are to be separated from other explosive material are to be separated from other buildings.buildings.

2.2. The notification specifies the type and number of The notification specifies the type and number of storeys a workplace can have, fire escape routes for storeys a workplace can have, fire escape routes for which there is to be no less than two clearly marked which there is to be no less than two clearly marked exits of no less than 1.50 meters in width. Fire exits of no less than 1.50 meters in width. Fire escape stairs must be fire resistant, smoke escape stairs must be fire resistant, smoke protected and opening out to a safe place, for protected and opening out to a safe place, for instance. instance.

3.3. As for fire fighting equipment, the employer is to As for fire fighting equipment, the employer is to provide the specified quantity of water and fire provide the specified quantity of water and fire extinguishers of certain types and capacities and extinguishers of certain types and capacities and install them at the locations as dictated by law. install them at the locations as dictated by law.



Main Points of the Law

3.3. The notification specifies measures used in The notification specifies measures used in monitoring the storage, quantity and usage of monitoring the storage, quantity and usage of inflammable substances stored within or inflammable substances stored within or without a building. without a building.

4.4. The notification specifies that inflammable The notification specifies that inflammable substances are to be stored in fire resistant substances are to be stored in fire resistant containers. It also specifies details on the containers. It also specifies details on the cleaning, collecting, elimination, burning and cleaning, collecting, elimination, burning and elimination of the ashes from these substances. elimination of the ashes from these substances.

5.5. Fire alarms are to be installed.Fire alarms are to be installed.




6.6. There are to be preventive measures for fires There are to be preventive measures for fires caused from heat of various sources such as caused from heat of various sources such as from electricity, friction of machinery, from electricity, friction of machinery, chimneys, heat waves, static electricity or chimneys, heat waves, static electricity or lightning, for instance. lightning, for instance.

7.7. Employees are to be trained to extinguish fires Employees are to be trained to extinguish fires in no less than 40% of the total space and fire in no less than 40% of the total space and fire drills are to be conducted at least once a year. drills are to be conducted at least once a year.

8.8. Employees are to be provided with individual Employees are to be provided with individual safety gear such as coats, shoes, gloves, hats safety gear such as coats, shoes, gloves, hats and heat resistant masks to be used in putting and heat resistant masks to be used in putting out fires or in drills.out fires or in drills.




Fire Protection and Prevention. Physics and Chemistry of Fire Fire: The rapid oxidation of material...

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Transcript of Fire Protection and Prevention. Physics and Chemistry of Fire Fire: The rapid oxidation of material...