Hazard ID and Properties of Hazardous Substances

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Hazard ID and Properties of Hazardous Substances

• Heritage Group Safety
• HAZWOPER Training

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Introduction

• In a response situation personnel may be exposed
  to a number of hazardous substances because of
  their chemical characteristics and physical
  properties.
• Basic knowledge of these characteristics and
  properties is paramount to personal safety.
  

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Topics of Discussion

• In Chapter 2 of Manual
• Hazardous Substances
• Physical Properties of Chemicals

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BIOLOGICAL HAZARDS

• The Five Biological Agents which can cause
  infection or disease in humans.
• What are they?
• Like chemical hazards Biological Hazards can be
  dispersed via air and water.
• Protection against these hazards is the same as
  for chemical hazards.

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RADIATION HAZARDS

• The three types of Radiation Alpha, Beta and
  Gamma
• Alpha and Beta are particle radiation while Gamma
  is wave radiations
• All are referred to as IONIZING Radiation and can
  upset human cellular function

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Alpha and Beta

• The Alpha is positively charged
• The Beta is negatively charged -
• Both are normally repelled by clothing or skin.
  They are dangerous when they enter the body
  through ingestion or inhalation.

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CHEMICAL HAZARDS

• Fire Hazards
• Explosive Hazards
• Toxic Hazards
• Corrosive Hazards
• Chemical Reactivity
• Physical Properties

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Fire Hazards

• Combustibility
• Flammability
• Pyrophorics
• Gas or Vapor Explosions

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Combustibility

• The ability of a material to act as a fuel
• OSHA says combustibles have flash point between
  100 F and 200 F
• Anything that can be readily ignited and sustain
  a fire
• Anything that cant is considered non-combustible

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The Fire Triangle

FUEL
OXYGEN
HEAT
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Flammability

• The ability of a material (gas or liquid) to
  produce sufficient vapors to be ignited and
  produce a flame under normal conditions.
• There must be a proper fuel to air mixture to
  sustain combustion. Each material has its own
  mixture range called Flammable Range.

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UFL and LFL

• Concentrations lt the LFL will not burn because
  they are too lean.
• Concentrations gt the UFL will not burn because
  they are too rich.

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OSHA FLAMMABLE

• OSHA considers anything flammable if it has a
  flash point below 100F.
• Flashpoint - See Section 2, page 14.

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REGULATORY CONFUSION

• OSHA-Flammable lt 100F
• Combustible 100F-200F
• Will Not Burn gt 200F
• DOT- Flammable lt 141F
• Combustible gt 141F but lt 200F
• Non-Hazardous Anything gt 200F
• EPA- Anything lt 140F is Ignitable

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GAS OR VAPOR EXPLOSIONS

• A Rapid, Violent Release of Energy
• Large amounts of kinetic energy, heat and gaseous
  products are released.
• The KEY is confinement of a Flammable Material.
  The combustion reaction is more rapid and
  confinement increases energy which enhances the
  explosive process.

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UEL and LEL

• Explosive gases and vapors exhibit an explosive
  range which is the same as the flammable range.
• The UEL (Upper Explosive Limit) and the LEL
  (Lower Explosive Limit) are the same as UFL and
  LFL, but in confined areas.
• Again, CONFINEMENT is the Key!

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EXPLOSIVE HAZARDS

• An Explosive is a substance which undergoes very
  rapid chemical transformation producing large
  amounts of gases and heat.
• Because of the heat the gases expand at
  velocities exceeding the speed of sound which in
  turn produces a shock wave and noise.

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Types of Explosive Hazards

• High or Detonating- Very rapid chemical
  transformation with detonation rates as high as
  four miles per second
• 1. Primary High Explosive
• 2. Secondary High Explosive
• Low or Deflagrating- Deflagration rate up to
  1,000 feet per second.

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Detonating vs Deflagrating

• In a Detonation rapidly expanding gases produce a
  shock wave which may be followed by combustion.
• In a Deflagration combustion is generally
  followed by a shock wave.
• (See examples in Section , page 8)
• WHAT ARE THE PRACTICAL CONSIDERATIONS?

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TOXIC HAZARDS

• Toxic hazards cause either a local or systemic
  effect on an organism and while death is not
  always certain it is an immediate concern.
• Types of toxic hazards are classified as to their
  physiological effect on the organism poisoning,
  asphyxiation, sensitization, and carcinogenicity
  are a few.

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Dose - Response

• Toxic effects on human beings depends on the
  length and amount of exposure and the level of
  toxicity (its lethal dose) of the material.
• HAZARD EXPOSURE TOXICITY
• Therefore, as the dose (length of exposure and
  amount of exposure) increases the human response
  increases also.

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CORROSIVE HAZARDS

• Corrosion is the process of material degradation.
  Corrosive materials may destroy human tissue,
  metals, plastics and other materials.
• Common corrosives are halogens, acids and bases.
  Skin irritation and possible irreversible tissue
  destruction are possible with exposure to
  corrosives.

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Acids, Bases and pH

• Materials that form the greatest number of
  hydrogen ions (H) are the strongest acids. Those
  that form the most hydroxide ions (OH-) are the
  strongest bases.
• The H ion concentration in solution is called
  pH. Therefore, strong acids have a low pH and
  strong bases have a high pH (fewer H ions) See
  pH scale on page 2-9.

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CHEMICAL REACTIVITY

• Reactivity Hazards- a chemical which undergoes a
  violent reaction with water or under normal
  ambient temperatures. (Pyrophoric liquids and
  water- reactive flammable solids).

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Chemical Reactions

• A Chemical Reaction is the interaction of two or
  more substances, resulting in chemical changes.
• Exothermic, which give off heat, can be the most
  dangerous.
• Endothermic reactions require a separate heat
  source to continue the reaction.

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Compatibility

• When two or more hazardous materials remain in
  contact with each other indefinitely they are
  compatible.
• On a waste clean-up site any number of instances
  where chemicals may be mixed are possible. One
  must know if such materials are compatible. If
  they are not, reactions may range from explosion
  to gas release.

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Compatibility

• See examples in Section 2, page12.
• WHAT ARE THE PRACTICAL CONSIDERATIONS?

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ITS MOVIE TIME!

• Introduction to Hazardous Chemicals
• The Emergency Film Group, Plymouth, MA
• 508-746-0466

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PHYSICAL PROPERTIES OF CHEMICALS

• One of the most ignored parts of an MSDS is the
  part where Physical Properties of Chemicals are
  listed.
• Most people do not understand Physical
  Properties.
• Evaluating risk on an incident depends on
  understanding these properties.

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Solubility/Miscibility

• The amount of chemical (solid, liquid, gas or
  vapor) which can be dissolved in water at 68F.
  Measured in percent, the higher the percentage,
  the more chemical that will dissolve in water.
• Example Sugar is 100 soluable.
• Miscibility refers, specifically, to the
  solubility of a liquid.

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Density and Specific Gravity

• The Density of a substance is its mass per unit
  volume, commonly expressed in grams per cubic
  centimeter (g/cc).
• The density of water is 1 g/cc.
• Specific Gravity is the density of a chemical
  compared to that of water. If the SpG is less
  than 1g/cc the chemical will float. If SpG is
  more than 1 g/cc it will sink.

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Vapor Density

• The Density of a gas or vapor can be compared to
  the ambient atmosphere. If the density of a
  vapor or gas is greater than ambient air, it will
  tend to settle.
• If Vapor Density is close to, or less than,
  ambient air it will rise or disperse in the
  atmosphere.
• Discuss hazards page 2-13.

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Vapor Density, continued

• What are the hazards of a gas or vapor which will
  settle? Use Carbon Monoxide as an example.
• How about Gasoline vapors?

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Vapor Pressure

• Pressure exerted, by a vapor, on the sides of a
  closed container.
• It is Temperature Dependent. As temperature
  increases, so does Vapor Pressure.
• The lower the boiling point of a liquid, the
  greater vapor pressure it will exert at a given
  temperature.

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Vapor Pressure, continued

• Values for Vapor Pressure are most often given as
  millimeters of mercury (mm Hg).
• NIOSH Handbook
• Examples Ammonia- VP 8.5 atm (p. 262)
  Carbon Monoxide (p. 54)
• Methyl hydrazine (p. 210)
• Atmospheric Pressure - 760 mm Hg.

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Boiling Point

• Temperature at which liquid changes to vapor.
  The temperature where the pressure of the liquid
  equals atmospheric pressure (760 mm Hg).
• What it the boiling point of Ammonia?
• What is the boiling point of Sulfuric Acid?
• What is the route of entry for each of these?

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Melting Point

• Temperature at which a solid changes to a liquid.
  It is also the freezing point-depends on the
  direction of the change.
• Example Water (ice) 32F

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Flash Point

• The minimum temperature at which a substance
  produces sufficient flammable vapors to ignite
• Highly Flammable
• Moderately Flammable
• Relatively Inflammable

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Odor Threshold

• The minimum concentration of a substance in air
  that can be detected by the human sense of smell.
  
• It is different for each person.
  Ammonia 5 ppm Ethyl
  alcohol 10 ppm
• The ACGIH STEL for Ammonia 25 ppm. What does
  this mean?

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IDENTIFYING HAZARDS

• Knowledge of the Hazards of various substance
  and an understanding of Physical Properties can
  be the difference between life and death.