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