NFPA 472 Definitions

Question 1

Acid

Answer 1

Compounds that forms hydrogen ions in water. These compounds have a pH less than 7, and acidic aqueous solution will turn litmus paper red. Materials with a pH less than 2 are considered strong acid.

Question 2

Concentration

Answer 2

The percentage of an acid or a base dissolved in water concentration is not the same strength.

Question 3

Compound

Answer 3

Chemical combination of two or more elements, either the same elements or different ones, that is electrically neutral. Compounds have a tendency to break down hinto their component parts, sometimes explosively.

Question 4

Air Reactivity

Answer 4

A substance that ignites spontaneously in air at or below 130.19 Fahrenheit. Most pyrophoeic fires should be extinguished with a class D extinguisher for burning metals.

Question 5

Chemical Change

Answer 5

Chemical changes occur when a substance combines with another to form a new substance, called synthesis or, alternatively, decomposes into two or more difference substances.

Question 6

Ignition (auto ignition) temperature

Answer 6

Minimum temperature required to ignite gas or vapor without a spark or flame being present. Significant in Evaluating the ease at which a flammable material may ignite.

Question 7

Auto-refrigeration

Answer 7

Auto-refrigeration is a phenomenon common to liquefied compressed gases. This is the process in which Liquefied gases are kept at its boiling point, so that any added heat is countered by energy lost from the boil off.

Question 8

Inhibitor

Answer 8

Added to products to control their chemical reaction with other products. If the inhibitor is not added or escapes during an incident, the material will begin to polymerize, possibly resulting in container failure.

Question 9

Halogenated Hydrocarbon

Answer 9

A hydrocarbon with halogenated atom (chlorine, Bromine, Fluorine) substituted for a hydrogen atom. They are often more toxic than naturally occurring organic chemicals, and they decompose for a smaller, more harmful elements when exposed to high temperature for a sustain period of time.

Question 10

Dose Response (relationship)

Answer 10

Basic principle of toxicology. The intensity of a response elicited by a chemical within a biologic mechanism is a function of the administered dose.

Question 11

Fire Point

Answer 11

Minimum temperature at which a liquid gives off sufficient vapors that will ignite and sustain combustion. It is typically several degrees higher than the flash point. In assessing the risks posed by a flammable liquids release, greater emphasis is placed upon the flash point, since it is a lower temperature and sustain combustion is not necessary for significant injuries or damage to occur.

Question 12

Flash point

Answer 12

Minimum temperature at which a liquid gives off enough vapors that will ignite and flash over but will not burn without the addition of more heat. Significant in determining the temperature at which the vapors from a flammable liquid are readily available and may ignite.

Question 13

Caustic (Base, alkaline)

Answer 13

Compound that forms hydroxides ion in water. These compounds have a pH of >7, and caustic solutionsa will turn litmus paper blue. Materials with a pH >12 are considered a strong base. Also known as alkali, alkaline or base.

Question 14

Critical temperature and pressure

Answer 14

Is the minimum temperature at which a gas can be liquified no matter how much pressure is applied.

Question 15

Expansion Ratio

Answer 15

The amount of gas produced by the evaporation of one volume of liquid at a given temperature. Significant property when evaluation liquid and vapor release of liquefied gases and cryogenic materials. The greater the expansion ratio, the more gas that is produced and the larger the hazard area.

Question 16

Dose

Answer 16

The concentration or amount of material to which the body is exposed over a specific time period. the amount of a substance ingested, absorbed and/or inhaled during an exposure period.

Question 17

Blood agents

Answer 17

Chemical agents that consists of a cyanide compound, such as hydrogen cyanide and cyanogen chloride. These agents are identical to their civilian counterparts used in industry.

Question 18

Half Life

Answer 18

The time it take for the activity of a radioactive material to decreases to one half of its initial value through radioactive decay. The half life of known materials can range from a fraction of a second to millions of years.

Question 19

Chemical interaction

Answer 19

Reaction cause by mixing two or more chemicals together. Chemical interactions of materials within a container may result in a build up of heat and pressure, leading to container failure.

Question 20

Boiling Point

Answer 20

The temperature at which a liquid changes it’s phase to a vapor or gas. The temperature where the vapor pressure of the liquid equals atmospheric pressure.

Question 21

Flammability (Explosive) range (LEL & UEL)

Answer 21

The range of gas or vapor concentration (percentage by volume in air) that will burn or explode if an ignition source is present. Limiting concentrations are commonly called the “lower flammability (explosive) limit and the upper flammability (explosive) limit. Below the lower flammability, the mixture is too lean or rich to burn; above the upper flammability limit, the mixture is too rich to burn. If the gas or vapor is released into oxygen enriched atmosphere, the flammability range will expand. Likewise if the vapor is released into a oxygen deficient atmosphere, the flammability range will contract.

Question 22

Biological agents and Toxins

Answer 22

Biological threat agents consist of pathogens and toxins. Pathogens are disease producing organisms and include bacteria and virus. Toxins re produced by a biological source and include ricin, botulinum and mycotoxins.

Question 23

Aromatic Hydrocarbon

Answer 23

A hydrocarbon containing benzene “ring” which is formed by six carbon atoms and contains resonant bonds.

Question 24

Instability (reactivity)

Answer 24

The ability of a material to undergo a chemical reaction with the release of energy. It could be initiated by mixing or reacting with other materials, application of heat, physical shock, etc.

Question 25

Corrosive

Answer 25

A material that causes visible destruction of or irreversible altercation to living tissues by chemical actions at the point of contact.

Question 26

Corrosivity

Answer 26

A material that causes visible destruction of or irreversible alterations to living tissue by chemical actions at the point of contact.

Question 27

Inorganic Materials

Answer 27

Compounds derived from other thanvegetable or animal sources which lack carbon chains , but may contain a carbon atom (Sulfur dioxide & Cyanide)

Question 28

Catalyst

Answer 28

Used to control the rate of chemical reaction by either speeding up or slowing down. If used improperly, catalyst can speed up a reaction and cause a container failure due to pressure or heat build up.

Question 29

Inorganic Materials

Answer 29

Compounds derived from other than vegetables and animals sources which lack carbon chains, but may contain a carbon atom

Question 30

Instability

Answer 30

The ability of a material to undergo a chemical reaction with the release of energy. It could be initiated by mixing or reacting with other materials, applications of heat, physical shock, etc.

Question 31

Ionic and Covalent compounds

Answer 31

The electrostatic attention of oppositely charged particles. Atoms or groups of atoms can form ions or complex ions. Covalent bonding is the force holding together atoms that share electrons

Question 32

Irritants (riot control agents)

Answer 32

Usually solid materials that are dispersed in a liquid spray and cause pain or burning on exposed mucous membranes and skins. Like pepper spray.

Question 33

Maximum safe storage Temperature (MSST)

Answer 33

The maximum storage temperature that an organic peroxide may be maintained, above which a reaction and explosion may occur.

Question 34

Melting Point/ Freezing Point

Answer 34

The temperature at which the a solid changes into a liquid. This temperature is also the freezing depending on direction of the change.

Question 35

Miscibility

Answer 35

Refers to the tendency or ability of two or more liquids to form a uniform blend or to dissolve in each other. Liquids may be totally miscible, partial or non miscible.h

Question 36

Mixture

Answer 36

Substance made up from two or more compounds, physically mixed together. A mixture may also contain elements and compounds mixed together.

Question 37

Nerve Agents

Answer 37

Nerve agents are a class of phosphorus containing organic chemicals that’s disrupt the mechanism by which nerves transfer messages to organs.

Question 38

Organic Materials

Answer 38

Material that contain carbon. Organic material are derived from materials that are living or were once living, such as plants or decayed products. Most organic materials are flammable.

Question 39

Oxidation potential (ability)

Answer 39

The ability of a material to either give up its oxygen molecule to stimulate the oxidation of organic material or receives electrons being transferred from the substance undergoing oxidation.

Question 40

Persistence

Answer 40

Refers to the length of time a chemical agent remains as a liquid. A chemical agent is said to be persistent it remains as a liquid for longer than 24 hours and non persistent if it evaporates within that time.