Hazmat Chapter 4
Partially water soluble chemicals penetrate into the lower respiratory system, causing delayed symptoms that include breathing difficulties, pulmonary edema, & coughing up blood.
12 - 24 hours
All flammable materials have auto ignition temperatures, in these are considerably higher than the flash and fire points. For example, the auto ignition temperature of gasoline is about___, but the flashpoint of gasoline is___.
536°F -45°F This difference means that @ -45° , gasoline will ignite if a match is waived through its vapors, whereas at 536°F it ignites all by itself.
Vapor density less than 1 indicates a vapor lighter than air,
A vapor density greater than 1 indicates a vapor heavier than air.
All reactions require some energy to get them started, which is commonly referred to as
Activation energy
All reported hazmat incidents are caused by container failure
Almost one fourth
Reactivity triangle Can be used to explain the basic components of many so not all chemical reactions
An oxidizing agent oxygen, a reducing agent fuel, & an activation energy source often heat, but not always so
Exposure/Contact
Anything such as persons, environment, or property that is in area of release exposed
Inhibitors
Are materials that are added to products that easily, rise in order to control or prevent an undesired reaction.
Strong oxidizers
Are materials that encourage a strong reaction by readily accepting electrons from reducing agents (fuel)
GEBMO helps 1st responders predict course of incident, thereby enabling them to limit effects of hazmat
Basically a defensive mode action that is concerned with potential hazmat emergencies involving containers
More predictable way of explaining the results of BLEVE
Blast Leveling Everything Very Evenly
Other important properties include
Boiling point, vapor pressure, vapor density, specific gravity, & solubility
Within the upper and lower limits, the gas or vapor concentration will
Burn rapidly if ignited
All vapors & gases will mix with air
But the lighter materials tend to rise and dissipate unless confined.
Reactivity triangle
Can be used to explain the basic components of many so not all chemical reactions
Boiling Liquid Expanding Vapor Explosion (BLEVE) also called violent rupture
Can occur when a liquid within a container is heated, causing the material inside to boil or vaporizer such as in the case of a liquefied petroleum gas tank exposed to a fire. If the resulting increase in internal vapor pressure exceeds the vessels ability to relieve the excess pressure, it can cause the container to fail catastrophically
When evaluating container stress,
Consider type of container, type & amount of stress, & its potential duration
Miscibility
Degree or readiness to which 2 or more gases or liquids are able to mix with or dissolve into each other
Harm
Depending on container, product, & energy involved, exposures may be harmed.
Persistent nerve agents will remain effective at their point of___ for a much longer time then non-persistent nerve agents.
Dispersion
Some substances will actually sublime or change directly from a solid, into a gas without going into a liquid state in between.
Dry ice (carbon dioxide) & mothballs both sublime rather than melt
The most common particulate contaminants include
Dust, fumes, mist, aerosols, & fibers,
Water solubility is also an important contributor for symptom development. Irritant agents that are water soluble usually cause
Early upper respiratory tract irritation, resulting in coughing & throat irritation.
Thermal
Excessive heat or cold causing intolerable expansion, contraction, weakening loss of temper, or consumption of the container & its parts
Mist
Finely divided liquid suspended in atmosphere. They are generated by liquids condensing from a vapor back to liquid or by breaking up liquid into dispersed state by splashing, foaming, or atomizing
The majority of hazardous materials incidents involvement areas that are
Flammable
A flammable hazard depends on properties such as
Flashpoint, autoignition temperature (sometimes called the autoignition point), & flammable (explosive or combustible) range.
Gas
Fluid that has neither independent shape nor volume, gases tend to expand indefinitely
Liquid
Fluid that has no independent shape but does have a specific volume. Liquids flow in accordance with laws of gravity
Aerosol
Form of mist characterized by highly respirable, minute liquid particles
3 states of matter
Gas, liquid, solid,
Vapor
Gaseous form of a substance that is normally in a solid or liquid state at room temperature & pressure. It is formed by evaporation from liquid or sublimation from a solid. Examples can be found where parts cleaning & painting takes place in solvents are used. Vapors are the volatile forms of these substances
Difficult if not possible to contain for mitigation purposes & will move according to prevailing wind & air movement
Gases
The majority of gases have a vapor density
Greater than 1
Ludwig Benner Jr.'s definition states that
Hazmats are things that can escape from their containers & hurt or harm things that they touch
Examples of materials with a vapor density less than 1 include
Helium, neon, acetylene, & hydrogen.
Upper explosive limit UEL or upper flammable limit UFL of a vapor or gas is
Highest concentration or highest percentage of the substance in air that will produce a flash of fire when an ignition source is present. At higher concentrations the mixture is too rich to burn.
Lighter than air gases, 13 chemicals that have a vapor density lighter than air normally presented using an acronym 4H MEDIC ANNA
Hydrogen .07 Hydrogen Cyanide 1.0 Helium .14 Hydrogen fluoride .34 Methane.55 Ethylene.96 Diborane.96 Illuminating gases .6 Carbon monoxide .96 Acetylene .9 Neon .34 Nitrogen .96 Ammonia .59
Stress
If a container is stressed beyond its design strength it fails or breaches
The weight of a substance compared to the weight of an equal volume of water is an expression of the density of a material for example
If a volume of a material weighs 8 pounds & equal volume of water weighs 10 pounds, material is said to have specific gravity of .8
And hazmat incidents the following sequence generally occurs
In this order, • stress • breach • release • dispersion/engulfed • exposure / contact • harm
Polymerization
Is a chemical reaction in which a catalyst causes simple molecules to combine to form long-chain molecules.
General Emergency Behavior Model (GEBMO)
Is based on a definition of hazardous materials developed by Ludwig Benner Jr.
Fire
Is just one type of chemical reaction
Wood, for example,
Is not as prone to undergo rapid oxidation that is, it will not burn as easily as a highly flammable liquid like MEK
Specific gravity
Is the ratio of the density heaviness of a material to the density of some standard material at standard conditions of pressure & temperature.
The reducing agent in the fire tetrahedron acts as the fuel source for the reaction, which basically means that
It is combining with oxygen or losing electrons to the oxidizer in such a way that energy is being released
If this reaction is uncontrolled,
It often results in a tremendous release of energy.
Persistence of a chemical is
Its ability to remain in the environment
Reactivity of a substance is
Its relative ability to undergo a chemical reaction with another material
In addition to other major categories of chemical reactive, first responders may see terms like these on MSDS &/or manufacturers labels, indicating that those products have an increased susceptibility to those particular sources of activation energy
Light sensitive, heat sensitive, or shock sensitive
Examples of catalysts include
Light, heat, water, acids, or other chemicals.
This will flow or pool according to surface contours & topography, providing opportunities for containment or confinement, naked wallpapers that become inhalation hazards, is primarily a splash or contact hazard.
Liquids
Heavier vapors & gases are likely to concentrate in
Low places along or under floors, in sumps, sewers, and manholes, and in trenches and ditches where they may create a fire or health hazards
Lower explosive limit LEL or lower flammable limit LFL of a vapor or gas is the
Lowest concentration or lowest percentage of the substance in air that will produce a flash of fire when an ignition source is present. At concentrations lower than the LEL, the mixture is too mean to burn
Reactions that have very low activation energies happen very easily for need very little help to begin the process. For example,
Materials that are generally classified as water reactive typically react with water easily at room temperature simply because heat being provided from surroundings is sufficient to start reaction.
Materials with specific gravities less than 1 will float in or on water.
Materials with specific gravity is greater than one will sink in water.
Flashpoint
Minimum temperature at which a liquid or volatile solid gives off sufficient vapors to form in ignitable mixture with air near its surface. At this temperature the vapors will flash (in the presence of an ignition source) but will not continue to burn
NFPA defines ignition temperature as
Minimum temperature required to initiate or cause self-sustained combustion, independent of heating element.
Autoignition temperature
Minimum temperature to which the fuel in air must be heated to initiate self-sustained combustion without initiation from an independent ignition source. This temperature is the point at which a fuel spontaneously ignites.
Chemicals that remain in the environment for a long time are
More persistent than chemicals that quickly dissipate or break down.
Some reducing agents fuels are
More volatile than others.
Release
One container is breached or fails, its contents, stored energy, and pieces of the container may release. The released product disperses.
Materials that may undergo violent polymerization is subjected to heat or contamination are designated with a
P in the blue and yellow sections of the ERG.
Air contaminants are commonly classified as either
Particulate or gas and vapor contaminants
Mechanical
Physical application of energy resulting in containers/attachment damage, may change shape of container crushing, reduce the thickness of container surface abrading or scoring, crack or produce gouges, unfasten or disengage the valves & piping, or penetrate container wall
Another term with which first responders should be familiar is
Polymerization
Compressed gases will expand rapidly when released
Potentially threatening large areas
Events in a hazmat incident follow general pattern or model.
Prediction may be based on past experience
Vapor pressure
Pressure exerted by saturated vapor above its own liquid in a closed container, or more simply, it is the pressure produced or exerted by the vapors released by liquid
Examples of materials with a vapor density greater than 1 include
Propane, hydrogen sulfide, ethane, butane, chlorine,& sulfur dioxide.
Dust
Solid particle that is formed or generated from solid organic or inorganic materials by reducing its size through mechanical processes such as crushing, grinding, drilling, abrading, or blasting.
Fiber
Solid particles whose length is several times greater than its diameter
May be moved by exterior forces (wind, water, gravity, etc) but will typically remain in place unless acted upon. Particle size such as dust, fumes, or powders may influence their behavior, example, how long particles may remain suspended in air. Larger particles will settle out more quickly.
Solids
Container stress is classified as
Stimulus causing strain excessive tension or compression, pressure force applied at right angles to a surface, or deformity distortion by torque or twisting
Solid
Substance that has both a specific shape without a container + volume
Undesirable effects may occur as a result of a reaction
Such as pressure build up, temperature increase, &/or formation of noxious, toxic, or corrosive by-products
Fume
Suspension of particles that form when material from volatilized(vapor state) solid condenses in cool air. In most cases, solid smoke like particles resulting from condensation react with air to form an oxide
Freezing point
Temperature at which a liquid becomes a solid at normal atmospheric pressure. For example, water freezes at 32°F it's freezing point.
NFPA defines auto ignition temperature as
Temperature at which a mixture will spontaneously ignite.
Melting point
Temperature at which a solid substance changes to a liquid state at normal atmospheric pressure for example an ice cube melt at just above 32°F
Fire point
Temperature at which enough vapors are given off to support continuous burning. This is usually only slightly higher than the flash point
Boiling point
Temperature at which vapor pressure of liquid is equal to or greater than atmospheric pressure. In other words, it is the temperature at which a liquid changes to a gas at a given pressure.
Solubility in water
Term expressing the percentage of a material by weight that will dissolve in water at ambient temperature
Flammable, explosive, or combustible range is
The percentage of the gas or vapor concentration in air that will burn or explode if ignited.
If liquid oxygen a cryogenic liquid is spilled on an asphalt roadway and sufficient activation energy is supplied from shock or friction such as someone stepping on it,
The roadway could explode
When a water soluble liquid combines with water
The two liquids mix easily, such as polar solvent alcohol, methanol, methyl ethyl ketone (MEK)
When a non water soluble liquid combines with water,
The two liquids remain separate, such as a hydrocarbon gasoline, diesel fuel, pentane
Breach
The way in which a container breaches is based on the material of which it is constructed, type of stress that it is exposed to, and pressure inside the container at the time that it fails. A breach container releases its contents
Common stressors are as follows
Thermal, Chemical, & Mechanical
Oxidation reduction reactions can be extremely violent and dangerous because
They are releasing a tremendous amount of energy.
Inhibitors maybe___ in that they may be___ over a period of time or when exposed to circumstances / unexpected contamination that cause them to be___ more rapidly, such as being___ by exposure to heat or other reaction triggers
Time sensitive Exhausted Consumed Overwhelmed
Oxidizing agent in the reactivity triangle provides the oxygen necessary for the chemical reaction.
True
The term ignition temperature is often used synonymously with auto ignition temperature or auto ignition point. They are always the same temperature.
True
Chemical
Uncontrolled reactions/interactions of contents in container & container itself, resulting in sudden or long-term deterioration of container.
Vapor density
Weight of a given volume of pure vapor or gas compared to the weight of an equal volume of dry air at the same temperature and pressure.
Breach p216
When container is stressed beyond its limits of recovery it's design strength or ability to hold contents, it opens & releases its contents
Dispersion / Engulf
When released, the product inside the container, any storage energy, & container disperse.
For example, many hydrocarbons such as petroleum products ignite spontaneously
When they come into contact with a strong oxidizer
The following facts regarding vapor pressure are important to first responders
• higher the temp of a substance, higher vapor pressure will be • vapor pressures reported on MSDS in mmHg are usually very low • lower the boiling point of substance, higher is the vapor pressure will be