What is a Hazardous Material?

A hazardous material is a material which is capable of producing

harmful physical or health effects.Harmful physical effects include fire, sudden release of pressure,

explosion, and other violent reactions.Harmful health effects include acute conditions and chronic

conditions.Acute conditions develop soon after over-exposure to hazardous

materials and include burns, rashes, respiratory distress, convulsions,

and possibly even death.Chronic conditions develop after long term exposure to hazardous

materials and include cancers, nervous system disorders, and damage

to other organ systems.

Acute:

Acute effects usually occur rapidly as a result of “short term”

exposure and are of short duration.

Chronic

Chronic effects generally occur as a result of “long term”

exposure and are of a long duration.

Carcinogen

A carcinogen is a chemical that causes cancer in humans or has the

potential to cause cancer (found causes cancer in laboratory

animals)

Irritant

An irritant chemical is one which is not corrosive but which causes

a REVERSIBLE inflammatory effect on living tissue by chemical

action at the site of contact

Sensitizer

A chemical which causes a substantial portion of exposed people to

develop an allergic reaction in normal tissue after repeated exposure

to the chemical.

• A hazardous material is any solid, liquid, or gas that can harm people, other living organisms, property, or the environment. Hazardous materials (hazmat) may be radioactive, flammable, explosive, toxic, corrosive, biohazardous, an oxidizer, an asphyxiant, a pathogen, an allergen, or may have other characteristics that render it hazardous in specific circumstances.

Classification of Hazardous Materials

Class 1 - Explosives

Class 2 - Gases (flammable, non-flammable, toxic)

Class 3 - Flammable liquids

Class 4 - Flammable solids, solids liable to spontaneous

combustion, and substances that emit flammable gases when wet

Class 5 - Oxidising substances (oxidising agents and organic

peroxides)

Class 6 - Toxic and infectious substances

Class 7 - Radioactive material

Class 8 - Corrosive substances

Class 9 - Miscellaneous dangerous substances

Class 1 - Explosives

Class 1.1 – Explosives with a mass explosion hazard such as TNT,

Gunpowder, Gelignite, etc.

Class 1.2 – Explosives which are a projectile or fragmentation

hazard, but not a significant mass explosion hazard eg. grenades,

ammunition, etc.

Class 1.3 – Explosives which are a fire and minor blast hazard, with

minor projectile or minor fragmentation hazards.

Class 1.4 – Explosives which are not a significant mass explosion

hazard eg. flares, fireworks, safety cartridges, etc.

Class 1.5 – Explosives with a mass explosion hazard, but are

insensitive substances.

Class 1.6 – Substances which are a minor explosion hazard, very

insensitive substances.

Class 2 - gases (flammable, non-flammable, toxic)

Completely gaseous at 20 degrees at Standard Temperature and Pressure

Class 2.1 – Gases that can ignite in air on contact with a source of ignition. The vapour/air density is usually greater than one, therefore many flammable gases will settle in low areas.

Example: propane, butane, ethylene, acetylene and Liquid Petroleum Gas (LPG)

Class 2.2 – Gases that are non flammable but may cause asphyxiation and/or represent stored energy hazard. Non flammable and non toxic gases are asphyxiants, diluting or replacing the oxygen content in the atmosphere.

Example: compressed air, nitrogen, argon and carbon dioxide

Class 2.3 – Gases likely to cause death or serious injury to human

health if exposed or by skin contact. These gases are toxic or

corrosive. Lingering and irritating odours often identify some but

not all toxic gases.

Example: ammonia and sulphur dioxide.

Class 2 - gases (flammable, non-flammable, toxic)

Completely gaseous at 20 degrees at Standard Temperature and Pressure

Liquids, the vapours of which can ignite in air on contact with a

source of ignition. Liquids that can generate a vapour, forming a

flammable mixture with air.

The vapour can flash momentarily when an ignition source is

present. This property of a flammable liquid is regarded as the flash

point. Therefore this is the lowest temperature of a liquid which

generates vapours to form a flammable mixture with air and can

catch fire when a flame is applied.

Examples of Class 3 substances:

petrol, alcohols, thinners, solvents, lacquers and varnishes

Class 3 - Flammable liquids

Flash Point

• Flash point means the minimum temperature at which a liquid

gives off enough vapor to form an ignitable mixture

– The lower the flash point, the greater the hazard

• Flammable liquids have flash points below 100oF

– May be ignited at room temperature

• Combustible liquids have flash points at or above 100oF

– Can pose serious fire and/or explosion hazards when heated

FLAMMABLE OR EXPLOSIVE LIMIT

In the case of gases or vapour, which form flammable mixtures with air, there is a minimum concentration of vapour in air below which the propagation of flame does not occur in contact with a source of ignition. This is called Lower Explosive Limit (LEL). Similarly, there is a maximum concentration of vapour above which the propagation of flame does not occur on contact with a source of ignition. This is called Upper Explosive Limit (UEL). This range of minimum to maximum concentration is termed as Flammable or Explosive range.

 

The flammable limits are not appreciably changed by normal variations in atmospheric pressure and temperature. However, at high temperatures, the upper limit is raised and the lower limit lowered, resulting in greater flammable or explosive range. The effect of high pressures on the limits is different for each gas or vapour depending upon its nature.

Class 4 - Flammable Solids

Solid substances which are flammable in air and can sustain

spontaneous combustion and emit flammable gases upon contact

with water.

Class 4.1 – Solids easily ignited eg. by sparks or flames, or liable

to cause fire through friction.

Example: red phosphorus, picric acid, hexamine, sulphur and

naphthalene.

Class 4.2 – Substances liable to spontaneously heat up and ignite

Examples: activated carbon and white phosphorus.

Class 4.3 – Substance which emits flammable or toxic gases when

wet

Examples: sodium and calcium carbide.

Class 5.1 – Substances likely to increase the risk and intensity of fire

in other materials (ie Contribute to the combustion of other

materials).

Examples: Hydrogen peroxide and ammonium nitrate, chlorates.

Class 5 – Oxidising substances

(oxidising agents and organic peroxides)

Oxygen is generally provided in a reactive form or is liberated to

cause an oxidation process.

Class 5.2 - Substances that are thermally unstable and likely to react

dangerously with other substances. Substances with the ability to

undergo exothermic self accelerating decomposition as the

substance contains its own oxygen in the chemical structure.

Decomposition of organic peroxides can lead to flammable and

toxic gases being generated. Many organic peroxides also burn

rapidly and are very sensitive to impact or friction.

Examples: dibenzoyl peroxide and methyl ethyl ketone peroxide

(MEKP)

Class 5 – Oxidising substances

(oxidising agents and organic peroxides) continued

Oxygen is generally provided in a reactive form or is liberated to

cause an oxidation process.

Class 6

Toxic and infectious substances

Class 6.1 – Toxic substances likely to cause death or severe injury to

human or animal health if swallowed, inhaled or by skin contact.

Examples: Calcium cyanide and lead arsenate.

Class 6.2 - Infectious substances liable to cause death or severe

injury to human or animal health if swallowed, inhaled or by skin

contact.

Class 7 - Radioactive material

Radioactive materials are materials that emit ionizing radiation with

an activity of greater than 0.002 micro curies per gram. Examples:

uranium, plutonium

Class 8 - Corrosive substances

Solids or liquids able to cause, to varying severity, damage to living tissue. Maybe either acidic or caustic in nature.

Cause burns in contact with skin and eyes.

Many form vapours that are harmful to respiratory system. Exposure can occur through breathing vapours.

In the event of a leak, these substances also have the ability to damage or destroy goods and materials or cause other hazards.

Examples:

Zinc Chloride Hydrochloric Acid Nitric Acid Sulfuric Acid (battery acid) Sodium Hydroxide (caustic soda) Ammonia solution

Class 8 - Corrosive substances

Class 9

Miscellaneous dangerous substances

Substances and articles that present a danger especially during

transport, not covered by other dangerous goods classes.

Class 9 substances have separate storage and transport

requirements.

Examples: dry ice and asbestos.

Hazard

Situation with a potential for damage to men, machines and environment.

Example : fire / explosion

• Fire hazard

• Explosion hazard

• Electrical hazard

• Toxic gas release hazard

• Hazardous chemical hazard

• Oil spillage

• Radiation hazard

• Fall from height

Major refinery potential hazards

Fire

Fire is a rapid, self-sustained oxidation process accompanied by the

release of energy in the form of heat and light of varying intensity.

Fire results from the combination of fuel, heat and oxygen. When a

substance is heated to a certain temperature called the ‘ignition

temperature’ the material will ignite and continue to burn as long as there

is fuel, the proper temperature and a supply of oxygen (air).

FIRE TRIANGLE

HEAT

FUEL

OXYGEN

Three elements are necessary for initiation of fire:

1. Fuel in the form of vapour, liquid or solid.

2. A source of ignition sufficient to initiate & propagate the fire.

3. Oxygen in sufficient proportion to form a combustible mixture

There are three requirements for starting and maintaining a fire:

• Fuel - wood, paper, oil, textiles, flammable gases etc.

• An oxidant - usually oxygen fron the air, but may be a chemical

in contact with the

fuel

• Heat - the temperature must be greater than the ignition

temperature of the fuel

There are three approaches to putting out a fire:

• Starvation - cutting off the fuel supply

• Smothering - separating the fuel from the oxidant

• Cooling - lower the temperature, usually with water

Classification of fire

Class A ; Fires involving ordinary combustible material like wood,

paper, textiles etc. where the cooling effect of water is essential for

extinguishments of fire. extinguishing media-water

Class B : Fires in flammable liquids like oils, solvents, petroleum

products, paints etc. Where a blanketing effect is essential to

extinguish the fire. Extinguishing media-foam, carbon dioxide, dry

chemical powder.

Class C: Fires involving gases or liquefied gases in the form of a

liquid spillage, or a liquid or gas leak. Extinguishing media - carbon

dioxide, dry chemical powder. The best way to extinguish such fires is

by stopping the flow of fuel gas to fire.

Class D : Fires involving metals like magnesium, aluminum, zinc,

potassium etc. Where the burning metal is reactive to water and which

require special extinguishing media.

Extinguishing media- special dry powder.

Electrical fire : Electrical fires are not treated as a class of their own,

since any fire involving, or started by, electrical equipment must, in

fact, fall into one of the other categories.

The normal procedure for dealing with an electrical fire is to cut off

electricity and use an extinguishing media appropriate to what is

burning.

FIRE RISK MANAGEMENT

Fire risk is ‘the chance/possibility of loss due to fire’. Three aspects

to deal with fire risk management are:

FIRE PREVENTION

FIRE PROTECTION

FIRE FIGHTING

WATER

The water is the best extinguishing media for Class A Fires. It is

• Readily available.

• Have good absorbing capacity.

• can be used as cooling agent, fire fighting, producing foam etc.

• Water extinguishes the fire by cooling , smothering ,

emulsification [only in case of heavy oils], dilution.

• Limitations: On

1. Energized equipments and

2. Water reactive metals.

Carbon Dioxide (CO2) extinguishers

The use of CO2 as an extinguishing agent is based on the principle

of lowering the percentage of oxygen within the fire area. The

fire is extinguished by a reduction of the oxygen content from the

normal 21 percent to 15 percent.

Further as carbon dioxide is denser than air it can form a blanket

over burning material. It is the smothering effect and not the

cooling effect which is most important.

The rapid expansion of the gas on discharging produces a

refrigerating effect, as indicated by the CO2 snow, which has a

temperature of minus 79°C (-110°F). This snow turns into gas and

in the process absorbs heat from the surrounding atmosphere.

. You cannot use a water extinguisher for a Class -B fire,

(flammable liquids), as flammable liquids are lighter than water and

will float on the surface of the water. This will simply aid in the

spread of the fire. Water fire extinguishers work by cooling and quenching a fire

(removing the element of heat from it) and carbon dioxide fire

extinguishers work by displacing oxygen at the source of the fire

with an inert gas (removing the element of oxygen from it) and they

also have a limited cooling effect.

FoamsA foam is a stable mass of air filled bubbles and has a lower

density than oil, gasoline or water. Surfactants which give water

surface properties suitable for foam formation are dissolved in

water, and when pressure is released on a mixture of the solution

and air a foam is formed.Foams work by:

• blanketing the fuel surface smothering the fire

• separating the surface of the fuel from the flames

• cooling the fuel and adjacent surroundings

• suppressing the release of flammable vapours that can mix with

airA variety of surfactants, based on fluorocarbons, hydrocarbons,

hydrolysed protein and solvents are used. They are used on both

class A and class B fires.

The dry chemical powder is used to extinguish the Class B and

Class C fires. The DCP for Class A fires is also available and for

Class D fires special dry chemical is used. Mainly sodium

bicarbonate is used

Sodium bicarbonate melts and decomposes at 270oC on heating.

2NaHCO3 = H2O + CO2 + Na2CO3

Thus at the temperature of the fire heat is absorbed by the

bicarbonate and carbon dioxide and water are produced. Thus

sodium bicarbonate works by absorbing heat from the fire and

giving products which would help smother it. Na2CO3 itself melts

at 851oC.

Dry chemical powder

CLASS OF FIRE

DESCRIPTION EXTINGUISHING MEDIUM

A Fire involving ordinary combustible materials like wood, paper, textiles, etc. Where the cooling effect of water is essential for the extinction of fires

Water

B Fire inflammable liquids like oils, solvents, petroleum products, varnishes, paints etc. where a blanketing effect is essential

Foam ** carbon dioxide dry chemical powder. Not suitable for alcohol and other water miscible flammable liquids

C Fires involving gaseous substances under pressure where it is necessary to dilute the burning gas at a very fast rate with an inert gas or powder.

Carbon dioxide dry chemical powder. The best way to extinguish such fires is by stopping the flow of fuel gas to the fire. Container is kept cool with water spray

D Fires involving metals like magnesium, aluminum, zinc, potassium etc. where the burning metal is reactive to water and which require special extinguisher media or technique

Special dry powder

Sources of Ignition

• Open flames• Smoking• Static electricity• Cutting and welding• Hot surfaces• Electrical and mechanical sparks• Lightning

Must take adequate precautions to prevent ignition of flammable vapors. Some sources of ignition include:

Static Electricity

• Static electricity can be generated by the contact and separation of dissimilar materials. For example: belts and pulleys, tires and the road, fluid flow through a pipe, agitation and mixing of fluids, and splash filling of flammable liquids.

• Generated when a fluid flows through a pipe or from an opening into a tank

• Main hazards are fire and explosion from sparks containing enough energy to ignite flammable vapors

• Bonding or grounding of flammable liquid containers is necessary to prevent static electricity from causing a spark

Bonding

• Physically connect two conductive objects together with a bond wire to eliminate a difference in static charge potential between them

• Must provide a bond wire between containers during flammable liquid filling operations, unless a metallic path between them is otherwise present

Grounding

• Eliminates a difference in static charge potential between conductive objects and ground

• Although bonding will eliminate a difference in potential between objects, it will not eliminate a difference in potential between these objects and earth unless one of the objects is connected to earth with a ground wire