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EMERGENCIES STAFF TRAINING PROGRAMS
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EMERGENCIES STAFF TRAINING PROGRAMS
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HAZARD
CLASSES All
chemicals, including hazardous ones, are commonly described in terms of their
physical, chemical, and biological properties.
It is necessary to understand the meaning and importance of the various
individual properties and also to have some grasp of the significance of the
numerical values given to chemical properties in order to fully use this
information to recognize and predict behavior so as to avoid potentially
dangerous situations.
D.O.T.: The Federal Department of Transportation (DOT) groups chemicals into 9 classes, depending on specific properties. Some classes are also broken up into divisions to further clarify groups within each class. Examples and general hazardous properties of different substances are shown in Table DOT. DOT CLASSES:
DOT 9: Miscellaneous Hazardous Materials Labels and Placards: The
identification system used in transportation consists of labels and placards. Labels: Labels are symbols (minimum of a 4-inch square diamond) that are attached to the shipping package. Packages classified as hazardous must have appropriate DOT markings or labels, unless otherwise specified. Additional requirements:
Placards: Placards are larger symbols (10-3/4” square diamond) that are attached to each side and end of a rail car, freight or portable tank container, or motor vehicle containing hazardous materials (> 640 ft3). Class 1 - Explosives: Explosives are materials that can react very rapidly, releasing a lot of energy. Flammables can act like explosives, depending on the container. Explosions are extremely difficult to protect against since they are not detectable. TNT (2,4,6-trinitrotoluene) and nitroglycerin are examples of explosives. The explosives hazard class placard is orange with an exploding ball icon. Class 2.1 - Flammable Gas: Any material which is a gas at 20°C (68°F) or less which is ignitable when in a mixture of 13% or less by volume with air; or has a flammable range with air of at least 12% regardless of lower limit. The placard for flammable gas has a red background with white lettering. Class 2.2 - Non-flammable Gas: Non-flammable gases are usually non-toxic, but pose hazards because they can displace oxygen, are under high pressure, and can be extremely cold or cryogenic. Examples of non-flammable gases are nitrogen, argon, and helium. The placard for non-flammable gas has a green background with white lettering. Class 2.3 - Inhalation Hazard: A material poisonous by inhalation (see § 171.8 of 49 CFR Part 171, May 6. 1997). Class 3 - Flammables and Combustibles: The ease of which a material burns can be categorized as either flammable or combustible. The flashpoint is what determines whether a material is flammable or combustible. Flammable liquids have a flashpoint equal to or less than 141o F and are by far the most common hazard class. Most solvents are flammable and can cause irritation and defatting when in contact with skin. Inhalation of vapors can cause dizziness and headache. The DOT placard for flammable materials is a flame on a red background with white lettering. Combustible liquids do not meet the definition of any other DOT hazard class and have a flashpoint more than 141o F and up to 200o F. Liquids that do not meet the definition of any other DOT hazard class and have a flashpoint of more than 200o F are classified as non-combustible. CLASS 4
- FLAMMABLE SOLIDS; SUBSTANCES THAT SPONTANEOUS COMBUST or SUBSTANCES, WHICH IN
CONTACT WITH WATER EMIT FLAMMABLE GASES Class
4 deals with substances, other than those classified as explosives, which, under
conditions of transport, are readily combustible or may cause or contribute to a
fire. Class 4 is subdivided as follows: Class 4.1 Flammable solids: Solids
which, under conditions encountered in transport, are readily combustible or may
cause or contribute to fire through friction; self-reactive substances (solids
and liquids) which are liable to undergo a strongly exothermic reaction; solid
desensitized explosives which may explode if not diluted sufficiently. The DOT placard for flammable
solids is a red and white vertical striped background
with black lettering and a black flame. Class 4.2 Substances liable to spontaneous combustion:
Substances (solids and liquids) which are liable to spontaneous
heating under normal conditions encountered in transport, or to heating up in
contact with air, and being then liable to catch fire. The DOT placard for
spontaneously combustible materials is a black flame with a white upper and a red
lower background
with black lettering. Class
5 - Oxidizers:
Oxidizing agents are usually recognizable by their structures or names.
Oxygen is usually in their structure and often released as a result of thermal
decomposition. Oxidizing agents often has “per-“ prefixes (perchlorate,
peroxide, and permanganate) and often ends in Strong
oxidizers have a larger potential incompatibility than perhaps any other
chemical group (with the exception of water reactive substances). It is safe to
assume that they shouldn’t be stored or mixed with any other material except
under carefully controlled conditions. The placard for the Oxidizer hazard class has a yellow back- ground with black lettering. The icon is a burning “0” which stands for oxygen. Oxidizers give off oxygen and promote the combustion process in other materials; therefore they are a fire hazard. Oxidizers increase the hazard of a material catching fire. Oxidizers can make flammables extremely flammable, and they make many corrosives act like flammables. Some oxidizers are very reactive and can cause burns similar to corrosives. Oxidizers can also bleach skin and hair. Class 6.1, Packing Group I or II - Poisons: A material, other than a gas, which is known to be so toxic to humans as to afford a hazard to health during transportation; or which, in the absence of adequate data on human toxicity, is presumed to be toxic to humans because it falls within any one of the following categories when tested on laboratory animals: oral toxicity, dermal toxicity, or inhalation toxicity. Poisons must enter the body to cause injury or illness and usually only a small amount of material is needed. The extent of injury depends on the route of exposure, the concentration or strength of the chemical, and the length of exposure time. Arsenic and cyanide are examples of poisons. The poison hazard class placard has a white background with black lettering and a skull and cross-bones icon. Class 6.1, Packing Group I or II - Inhalation Hazard: A material poisonous by inhalation (see § 171.8 of 49 CFR Part 171, May 6. 1997). Class 6.1, Packing Group III - Keep Away from Food: Substances that are liable to cause death, serious injury or harm to human health if swallowed, inhaled, or contacted by skin. This poison hazard class placard has a white background with black lettering and an X-ed out ear of corn. Class 6.2, - Infectious Substance:
A viable microorganism (or its toxin) which causes or may cause disease in
humans or animals. Includes those agents listed in the Department of Health and
Human Services' Regulations (42 CFR 72.3) and any other agent that has the
potential to cause severe, disabling, or fatal disease. Class 7 - Radiation has two sources: Natural background sources (70%) such as rocks which emit radon gas or contain other radioactive elements, and man-made sources (30%) such as X-ray machines. Man-made or naturally occurring radioactive isotopes are used every day and waste products from these manmade sources fall into two categories: High-level radioactive waste and low-level radioactive waste. There are two common types of radiation. 1) Ionizing Radiation (concentrated package of energy). Alpha radiation. Alpha particles are double-charged
helium ions and are Beta radiation. Beta radiation is a fast moving
electron that is produced Gamma, X-ray. Gamma
rays and X-rays are commonly classified as 2) Non-ionizing Radiation (energy transmitted as a wave). These types of radiation
are heat producing. Non-ionizing radiation can be created or is utilized for many operations. Radar detectors, microwaves, radio, TV, and cellular phones all use non-ionizing radiation. Electromagnetic radiation is emitted as two fields (magnetic and electrical). The electrical field is produced from the transmitted current and the voltage transmitted produces the magnetic field. Radiation protection measures are based upon limiting or minimizing the absorbed dose. This can be accomplished by reducing the time exposed, increasing the distance from the source, and utilizing shielding (i.e., water, concrete, steel, soil, etc.). Class 8 - Corrosives are defined in terms of pH by the EPA and have a pH < 2 or > 12.5. The DOT defines corrosivity in terms of the substance’s ability to cause visible destruction or changes in skin tissue at the site of contact or a liquid that has a severe corrosion rate on steel or aluminum. Strong acids and strong bases are corrosive. Acids are compounds that yield H+ (hydrogen) ions when dissolved in water. Chemicals ending with “ic” are always acids. Examples of these acids include hydrochloric and acetic acids. The terms “concentrated” and “dilute” refer to the concentration of the acid in solution. Acids are defined as solutions with a pH < 7. The pH is defined as the negative logarithm of the molar H+ concentration (i.e. –log[H+]). Bases are materials that produce hydroxide ions (OH-) when dissolved in water. The words “alkaline,” “basic,” and “caustic” are often used interchangeably. Chemicals ending with "ide" are bases 60% of the time and are bases 100% of the time when ending with "hydroxide." Common bases include sodium hydroxide (lye), potassium hydroxide (potash lye), and calcium hydroxide (slaked lime). Strong versus weak bases, and concentrated versus dilute bases are terms that are exactly analogous to those for acids. Strong bases dissociate completely while weak bases such as the amines dissociate only partially. As with acids, bases can be either inorganic or organic. The halogens such as iodine, fluorine, chlorine and bromine are also very strong corrosives. Although they are too reactive to occur naturally in the environment, they can form dangerous compounds. Extreme caution is necessary when handling halogen compounds because they are also strong oxidizers and readily bond with hydrogen to form acids. The placard for corrosives consists of white lettering on a split background showing a hand and a piece of material being eaten away. Contacting corrosives causes immediate damage to skin or eyes, and inhalation of vapors will cause irritation and burning of the nose, throat, and lungs. Ingesting corrosives will irritate and bum the mouth, throat and stomach. Corrosives will chemically react and generate heat that can act as an ignition source, potentially causing a fire. Class 9 - Miscellaneous: A material which presents a hazard during transport but which is not included in any other hazard class. This class includes any material which has an anesthetic, noxious, or other similar property which could cause extreme annoyance or discomfort, or any material (not included in any other hazard class) which meets the definition of a hazardous substance or hazardous waste. This placard has a white background with black vertical stripping on the upper half.
INCOMPATIBLES:Chemical
incompatibility can manifest in many ways, with combinations resulting in fires,
explosions, extreme heat, evolution of toxic gases, and polymerization. Because
of the great number of chemicals and subsequent multiple numbers of potential
reactions, it is impractical to list all potential reactions; five of the more common incompatibility reactions are shown below. Different hazard
classes should never be stored together because violent reactions occur when the
following hazard classes are mixed together:
1. CORROSIVES + FLAMMABLES ==> EXPLOSION/FIRE 2. CORROSIVES + POISONS ==> POISON GAS 3. FLAMMABLES + OXIDIZERS ==> EXPLOSION/FIRE 4. ACIDS + BASES ==> SALTS/HEAT 5. WATER REACTIVES + WATER ==> TOXIC or FLAMMABLE GAS NFPA NFPA Labeling System The diamond shaped diagram gives a general idea of the inherent hazards and the severity of these hazards under emergency conditions. The Health, Flammability and Reactivity are designated with 0 (or blank) indicating no hazard and 4 indicating an extreme or severe hazard; Special Hazards contain symbols that designate other hazards (if present). Table NFPA contains the full explanation of the numbering system for Health, Flammability and Reactivity. The symbols seen in Special Hazards include: Oxidizer OXY Acid ACID Alkali ALK Corrosive COR
Radiation Hazard Use NO
AIR Table NFPA:
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DOT/
DOT 1: Explosives 
DOT 2: Gases
DOT 3: Flammable
Liquids
DOT 4:
Flammable Solids
DOT 5: Oxidizing Substances
DOT 6: Poisons
DOT 7: Radioactive
Materials
DOT
8: Corrosive Materials
