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MAGNESIUM Magnesium (Mg) is a metallic element, discovered as an oxide by Sir Humphrey Davy in 1808. A ductile, silver-white, chemically active Alkaline-Earth Metal, it is the eighth most abundant element in the earth's crust. Its commercial uses include lightweight alloys in aircraft fuselages, jet-engine parts, rockets and missiles, cameras, and optical instruments. The metal is used in pyrotechnics. Magnesium is found in plant chlorophyll and is necessary in the diet of animals and humans . (Hydro Cut General Terminology & Resource Information)

MAJOR OCCUPANCY ...means the principal occupancy for which a building or part thereof is used or intended to be used, and includes the subsidiary occupancies that are an integral part of the principal occupancy. (Ontario Fire Code 1996)

MANHATTAN PROJECT The Manhattan Project was the wartime effort to design and build the first nuclear weapons (Atomic Bomb). A $2-billion effort, centered at Oak Ridge, Tenn., and Hanford, Wash., was required to obtain sufficient amounts of the two necessary isotopes, uranium-235 and plutonium-239. The design and building of the bombs took place at Los Alamos, N.Mex., where J. Robert Oppenheimer directed a large group of American and European-refugee scientists. Following the test explosion of a plutonium device on July 16, 1945, near Alamogordo, N.Mex., a uranium bomb and a plutonium bomb were dropped on, respectively, Hiroshima (Aug. 6) and Nagasaki (Aug. 9) . (Hydro Cut General Terminology & Resource Information)

MANIFEST, UNIFORM HAZARDOUS WASTE A document required by 40 CFR 262 to accompany any shipment of hazardous waste from the point of generation to the point of final disposal/destruction. (See Shipping Papers, and Hazardous Waste Manifest, Uniform (EPA).) HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

MARKING The required descriptive name, instructions, cautions, weight, or specifications or combination thereof on containers of hazardous materials/hazardous waste . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

MASS The inertial property of an object, which is proportional to force needed to accelerate the object in the absence of resistance . [Friedman 1989]

MASS Confusion often exists between mass and weight. Weight refers to the force acting on an object because of gravitational attraction, and is a convenient way to measure mass on Earth at sea level. However, if an object were on the moon, its weight would be only about 1/6th of its weight on Earth, or if the object were in an orbiting space station it would be weightless; however, its mass would be the same in each case . [Friedman 1989]

MASS Mass in physics is the quantity of matter in a body regardless of its volume or of any forces acting on it. There are two ways of referring to mass, depending on the laws of physics defining it. The gravitational mass of a body may be determined by comparing the body on a beam balance with a set of standard masses; in this way the gravitational factor is eliminated ( Gravitation; Weight). The inertial mass of a body is a measure of the body's resistance to acceleration by some external force. All evidence seems to indicate that the gravitational and inertial masses are equal. According to the special theory of Relativity, mass increases with speed according to the formula m = m0/_1-v2/c2, where m0 is the rest mass (mass at zero velocity) of the body, v its speed, and c the speed of light in vacuum. The theory also leads to the Einstein mass-energy relation E = mc2, where E is the energy and m the relativistic mass . (Hydro Cut General Terminology & Resource Information)

MASS NUMBER Mass number is represented by the symbol A, the total number of nucleons ( Neutons and Protons) in the nucleus of an Atom. All atoms of a chemical Element have the same Atomic Number but may have different mass numbers (from having different numbers of neutrons in the nucleus). Atoms of an element with the same mass number make up an Isotope of the element. Isotopes of different elements may have the same mass number but different numbers of protons . (Hydro Cut General Terminology & Resource Information)

MASS RATIO The ratio of the initial mass of the propellant to the mass of the complete rocket motor . (Hydro Cut General Terminology & Resource Information)

MATERIAL FIRST IGNITED The fuel that is first set on fire by the heat of ignition. To be meaningful, both a type of material and a form of material should be identified . [NFPA 921 - 1992]

MATERIAL SAFETY DATA SHEET (MSDS) A document which contains information regarding the specific identity of hazardous chemicals, including information on health effects, first aid, chemical and physical properties, and emergency phone numbers . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

MATTER Matter is anything that has mass. Because of its mass, all matter has Weight, if it is in a gravitational field, and Inertia. The three common States Of Matter are solid, liquid, and gas; scientists also recognize a fourth, Plasma. Ordinary matter consists of Atoms and Molecules. See also Element; Elementary Particles . (Hydro Cut General Terminology & Resource Information)

MEAN OR AVERAGE MEAN Unless otherwise specified, this is the arithmetic mean of the observations. A measure of the variability or dispersion of a number of observations . (Hydro Cut General Terminology & Resource Information)

MEANS OF EGRESS ...means a continuous path of travel provided for the escape of persons from any point in a building or contained open space to a separate building, an open public thoroughfare or an exterior open space protected from fire exposure from the building and having access to an open public thoroughfare. Means of egress includes both exits and access to exits. (Ontario Fire Code 1996)

MECHANICS Mechanics is a branch of physics concerned with Motion and the Forces causing it. The field includes the study of the mechanical properties of matter, such as Density, Elasticity ( Strength Of Materials), and Viscosity. Mechanics is divided into Statics, which deals with bodies at rest or in equilibrium, and Dynamics, which deals with bodies in motion. Isaac Newton, who derived three laws of motion and the law of universal Gravitation, was the founder of modern mechanics. For bodies moving at speeds close to that of light, Newtonian mechanics is superseded by the theory of Relativity, and for the study of very small objects, such as Elementary Particles, Quantum theory is used . (Hydro Cut General Terminology & Resource Information)

MEDIAN The halfway point in the measurements when they have been arranged in order of size . (Hydro Cut General Terminology & Resource Information)

MELTING POINT Melting point, temperature at which a substance changes its state from solid to liquid (see States Of Matter). Under standard atmospheric pressure, different pure crystalline solids will each melt at a different specific temperature; thus melting point is a characteristic of a substance and can be used to identify it. The quantity of heat necessary to change 1 gram of any substance from solid to liquid at its melting point is known as its latent heat of fusion . (Hydro Cut General Terminology & Resource Information)

... The temperature at which a material changes from a solid to a liquid . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

MELTING POINTS OF AIRCRAFT MATERIALS

6170 F TUNGSTEN melts
4760 F MOLYBDENUM melts
3430 F CHROMIUM melts
3150 F VANADIUM melts
3100 F PURE TITANIUM melts
2820 - 3000 FTITANIUM ALLOYS melt
2800 F IRON melts
2700 FSTAINLESS STEEL melts
2650 F NICKEL melts
2600 F SILICON melts
2270 F MANGANESE melts
2250 F Porcelain glazes
2000 F COPPER melts
1940 F GOLD melts
1760 F SILVER melts
1675 F BRONZE melts
1600 - 2000 F BRASS BEARINGS melt
1400 - 1600 F Glass softens
1250 F ALUMINIUM ALLOYS melt
Magnesium alloys melt
1220 - 1250 F Aluminium bearings melt
1200 F PURE MAGNESIUM melts
Glass cloth fuses
1175 F PURE ALUMINIUM melts
Aluminium panelling melts
1165 - 1450 F SILVER SOLDER melts
890 F ALUMINIUM EUTECTIC melting
850 F Aluminium becomes plastic, sags
780 F ZINC melts
700 F SILCON RUBBER blisters
630 F TEFLON INSULATION melts
625 F LEAD melts
610 F CADMIUM melts
480 F NYLON melts
450 F TIN melts
430 F SELENIUM melts
275 F Wool decomposes
250 - 300 F Nylon spaghetti melts
250 F PHENOLIC delaminates
210 F POLYSTYRENE distorts
Methyl methacrylate distorts
185 F Plastic PCV distorts
130 F Wax melts

Source : R. H. WOOD, R.W. SWEGINNIS; AIRCRAFT ACCIDENT INVESTIGATION , Endeavor Books, Casper WY, 1995, p.59

MERCANTILE OCCUPANCY (Group 'E') ...means the occupancy or use of a building or part thereof for the displaying or selling of retail goods, wares or merchandise. (Ontario Fire Code 1996)

METAL A chemical Element displaying certain properties, notably metallic luster, the capacity to lose electrons and form a positive Ion, and the ability to conduct heat and electricity ( Conduction), by which it is normally distinguished from a nonmetal. The metals comprise about two thirds of the known elements. Some elements, e.g., arsenic and antimony, exhibit both metallic and nonmetallic properties, and are called metalloids. Metals fall into groups in the Periodic Table determined by similar arrangements of the orbital electrons and a consequent similarity in chemical properties. Such groups include the Alkali Metals (Group la in the periodic table), the Alkaline - Earth Metals (Group IIa), and the Rare - Earth Metals ( Lanthanide and Actinide series). Most metals other than the alkali metals and the alkaline-earth metals are called transition metals ( Transition Elements). The oxidation states, or Valence, of the metal ions vary from +1 for the alkali metals to +7 for some transition metals. Chemically, the metals differ from the nonmetals in that they form positive ions and basic oxides and hydroxides. Upon exposure to moist air, a great many metals undergo corrosion, i.e., enter into a chemical reaction, the oxygen of the atmosphere uniting with the metal to form the oxide of the metal, e.g., rust on exposed iron . (Hydro Cut General Terminology & Resource Information) f

METALS Metals are a special kind of solid. Metals generally consist of positively charged atomic ions in a geometrically defined crystal lattice, with electrons free to move through the lattice. The fact that metals conduct heat and electricity far !better than other solids is due to the high mobility of the electrons through the crystal lattice. A metal can consist of a single pure element (such as copper, aluminum, iron, or 24-carat gold), or it can be an alloy of two or more elements. For example, brass is an alloy of copper and zinc, steel is an alloy of iron and carbon, and 18-carat gold is an alloy of gold and silver . [Friedman 1989]

METAPHOR / implied comparison achieved through a figurative use of words; the word is used not in its literal sense, but in one analogous to it.
*Life's but a walking shadow; a poor player, That struts and frets his hour upon the stage. Shakespeare, Macbeth
*. . . while he learned the language (that meager and fragile thread . . . by which the little surface corners and edges of men's secret and solitary lives may be joined for an instant now and then before sinking back into the darkness. . . ) Faulkner, Absalom, Absalom!
*From Stettin in the Baltic to Trieste in the Adriatic, an iron curtain has descended across the continent. W. Churchill (A Glossary of Rhetorical Terms with Examples, Ross Scaife)

METHANE

Methane (CH4) is a colorless, odorless, gaseous Hydrocarbon formed by the decay of plant and animal matter. It occurs naturally as the chief component of Natural Gas, as the firedamp of coal mines, and as the marsh gas released in swamps and marshes. Methane can also be made synthetically by various means. It is combustible and can form explosive mixtures with air. Used for fuel in the form of natural gas, methane is also an important starting material for making solvents and certain Freons. (Hydro Cut General Terminology & Resource Information)

METHANE If there is a stoichiometric mixture of methane and air (9.5% CH4, 19% O2, and 71.5% N2), it would burn and the flame temperature would be 1940C . [Friedman 1989]

METHANOL Methanol, or methyl alcohol or wood alcohol (CH3OH), a colorless, flammable liquid and the simplest Alcohol. Methanol is a fatal poison. Small internal doses, prolonged exposure of the skin to the liquid, or continued inhalation of the vapor may cause blindness. It can be obtained from wood, but now is made synthetically from the direct combination of hydrogen and carbon monoxide gases. Methanol is used to make Formaldehyde, as a solvent, and as an Antifreeze . (Hydro Cut General Terminology & Resource Information)

METONYMY / substitution of one word for another which it suggests.
*He is a man of the cloth.
*The pen is mightier than the sword.
*By the sweat of thy brow thou shalt eat thy bread. (A Glossary of Rhetorical Terms with Examples, Ross Scaife)

MICROMETER An instrument used for measuring extremely small distances. In the micrometer caliper, the object to be measured is held between the two jaws of the instrument; the distance between the jaws is measured on a scale calibrated to the rotation of the finely threaded screw that moves one of the jaws. In astronomical and microscopic micrometers, the distance that a filament moves from one end to the other of the image of an object is read on a calibrated scale . (Hydro Cut General Terminology& Resource Information)

MICRON One micron equals 10-4 cm or may also be expressed as 10-6 meters. . A unit of length, the thousandth part of one millimeter. A particle of diameter between 0.01 and 0 0001 millimeter . (Hydro Cut General Terminology & Resource Information)

MICROPHONE A device (invented c.1877) used in radio broadcasting, recording, and sound-amplifying systems to convert sound into electrical energy. Its basic component is a flexible diaphragm that responds to the pressure or particle velocity of sound waves. In a Capacitor, or condenser, microphone, used in high-quality sound systems, two parallel metal plates are given opposite electrical charges. One of the plates is attached to the diaphragm and moves in response to its vibrations, generating a varying voltage . Also Telephone. (Hydro Cut General Terminology & Resource Information)

MICROSECOND One millionth of a second, 10-6 second, expressed as msec . (Hydro Cut General Terminology & Resource Information)

MIDNIGHT DUMPING Illegal disposal of hazardous materials . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

MILLISECOND One thousandth of a second, 10-3 second, expressed as msec . (Hydro Cut General Terminology & Resource Information)

MINIMUM IGNITION ENERGY The energy, in milijoules, of the weakest spark that is just capable of igniting a gas mixture. The minimum energy depends on the composition, temperature, and pressure of the mixture . [Friedman 1989]

MISHAP That process by which a normal, stable activity is transformed and produces an undesired and usually unplanned outcome . (Synonym for accident) [Benner 1997]

MISSILE Any object thrown, dropped, fired, launched or otherwise projected with the purpose of striking a target. Short for "ballistic missile", "guided missile." (Missile is loosely used as a synonym for "rocket" or spacecraft by some careless writers.) (Hydro Cut General Terminology & Resource Information)

MIST Suspended liquid droplets generated by condensation from the gaseous to the liquid state or by breaking up a liquid into a dispersed state, such as by splashing, foaming, or atomizing. A mist is formed when a finely divided liquid is suspended in air . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

MOCKUP A model (often crude) for study or training . (Hydro Cut General Terminology & Resource Information)

MOLE A quantity of a chemical substance equal to its molecular weight in grams . [Friedman 1989]

MOLE A mole in chemistry is a quantity of particles of any type equal to Avogadro's number. One gram-atomic weight (or one gram-molecular weight) the amount of an atomic (or molecular) substance whose weight in grams is numerically equal to the Atomic Weight (or Molecular Weight) of that substance contains exactly one mole of atoms (or molecules). (Hydro Cut General Terminology & Resource Information)

MOLECULAR WEIGHT

Molecular weight is the weight of a Molecule of a substance expressed in atomic mass units ( Atomic Weight). The molecular weight is the sum of the atomic weights of the atoms making up the molecule. (Hydro Cut General Terminology & Resource Information)

MOLECULE

A molecule is the smallest particle of a Compound that has all the chemical properties of that compound. Molecules are made up of two or more Atoms, either of the same Element or of two or more different elements. Ionic compounds, such as common salt, are made up not of molecules but of ions arranged in a crystalline structure ( Crystal). Unlike Ions, molecules carry no electrical charge. Molecules differ in size and Molecular Weight as well as in structure ( Isomer). (Hydro Cut General Terminology & Resource Information)

MOTION Motion, in Mechanics, the change in position of one body with respect to another. The study of the motion of bodies is called Dynamics. The time rate of linear motion in a given direction by a body is its velocity; this rate is called the speed if the direction is unspecified. If during a time t a body travels over a distance s, then the average speed of that body is s/t. The change in velocity (in magnitude and/or direction) of a body with respect to time is its acceleration. The relationship between Force and motion was expressed by Isaac Newton in his three laws of motion: (1) a body at rest tends to remain at rest, or a body in motion tends to remain in motion at a constant speed in a straight line, unless acted on by an outside force; (2) the acceleration a of a mass m by a force F is directly proportional to the force and inversely proportional to the mass, or a = F/m; (3) for every action there is an equal and opposite reaction. The third law implies that the total Momentum of a system of bodies not acted on by an external force remains constant ( Conservation Laws). Motion at speeds approaching that of light must be described by the theory of Relativity, and the motions of extremely small objects (atoms and elementary particles) are described by quantum mechanics (Quantum theory). (Hydro Cut General Terminology & Resource Information)

MULTI-HAZARD FUNCTIONAL PLANNING

The California format used for developing disaster and emergency plans . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

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NAPALM A gasoline thickener . (Hydro Cut General Terminology & Resource Information)

NARCOTIC EFFECT The effect of producing drowsiness and ultimately unconsciousness. Chemical substances in smoke, when inhaled, can enter the bloodstream and interfere with the oxygen supply to the brain, causing narcosis and possibly death . [Friedman 1989]

NATIONAL FIRE PROTECTION ASSOCIATION Standards for explosive materials and ammonium nitrate issued by the National Fire Protection Association . (Hydro Cut General Terminology & Resource Information)

NATIONAL FIRE PROTECTION ASSOCIATION (NFPA) An international voluntary membership organization to promote improved fire protection and prevention, establish safeguards against loss of life and property by fire, and writes and publishes the American National Standards . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

NATIONAL INTERAGENCY INCIDENT MANAGEMENT SYSTEM (NIIMS) A standardized systems approach to incident management that consists of five major sub-divisions collectively providing a total systems approach to all-risk incident management . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH (NIOSH) A Federal agency which, among other activities, tests and certifies respiratory protective devices, air sampling detector tubes, and recommends occupational exposure limits for various substances . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

NATIONAL RESPONSE CENTER (NRC) A communications center operated by the United States Coast Guard headquarters located in Washington, DC. They provide information on suggested technical emergency actions, and must be notified by the spiller within 24 hours of any spill of a reportable quantity of a hazardous substance . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

NATIONAL SAFETY COUNCIL (NSC) A nonprofit organization chartered by Congress to provide a regular information service on the causes of accidents and ways to prevent them . (Hydro Cut General Terminology & Resource Information)

NATURAL GAS Natural gas, natural mixture of flammable gases found issuing from the ground or obtained from specially driven wells. Largely a mixture of Hydrocarbons, natural gas is usually 80 to 95% Methane. The composition varies in different localities, and minor components may include carbon dioxide, nitrogen, hydrogen, carbon monoxide, and helium. Often found with Petroleum, natural gas also occurs apart from it in sand, sandstone, and limestone deposits. Natural gas began to be used as an illuminant and a fuel on a large scale in the late 19th century, when pipelines were built to provide it to large industrial cities. Liquified natural gas (LNG) is natural gas that has been cooled and pressurized to liquify it for convenience in shipping and storage . (Hydro Cut General Terminology & Resource Information)

NEON (Ne), gaseous element, discovered in 1898 by William Ramsay and M.W. Travers. A colorless, odorless, and tasteless inert gas, it emits a bright-red glow when conducting electricity in a tube. Neon is used in advertising signs, Lasers, Geiger counters, Particle Detectors, and high-intensity beacons. Liquid neon is a cryogenic refrigerant . (Hydro Cut General Terminology & Resource Information)

NEUTRALIZATION The process by which acid or alkaline properties of a solution are altered by addition of certain reagents to bring the hydrogen and hydroxide concentrations to equal value (pH 7 is neutral) . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

NEWTON, SIR ISAAC Sir Isaac Newton, 1642 - 1727, English mathematician and natural philosopher (physicist); considered by many the greatest scientist of all time. He was Lucasian professor of mathematics (1669û1701) at Cambridge University. Between 1664 and 1666 he discovered the law of universal Gravitation, began to develop the Calculus, and discovered that white light is composed of every color in the Spectrum. In his monumental Philosophiae naturalis principia mathematica {Mathematical Principles of Natural Philosophy} (1687), he showed how his principle of universal gravitation explained both the motions of heavenly bodies and the falling of bodies on earth. The Principle covers Dynamics (including Newton's three laws of Motion), Fluid mechanics, the motions of the planets and their satellites, the motions of the comets, and the phenomena of tides. Newton's theory that Light is composed of particles ù elaborated in his Opticks (1704) ù dominated optics until the 19th cent., when it was replaced by the wave theory of light; the two theories were combined in the modern Quantum theory. Newton also built (1668) the first reflecting telescopeE, anticipated the calculus of variations, and devoted much energy towards alchemy, theology, and history. He was president of the Royal Society from 1703 until his death . (Hydro Cut General Terminology & Resource Information)

NFPA 907M - 1983 MANUAL ON THE INVESTIGATION OF FIRES OF ELECTRICAL ORIGIN 1-1 Scope To establish guidelines and techniques for use in investigating fires to determine whether or not a fire is of electrical origin with a view TO IMPROVING THE CREDIBILITY OF SUCH INVESTIGATIONS and developing information that can be useful in improving the fire safety of electrical equipment. 1-2 Purpose. This manual is intended to establish guidelines [directives] and techniques for use in investigating and reporting fires so that it can be determined if the fire was or may have been of electrical origin. The fire officer at the scene is potentially the best source of accurate information as to the location and origin of a fire. This manual is intended to provide the fire officer with additional background so that an accurate determination can be made to establish whether the ignition of the fire was a direct or indirect result of electricity. [...] The primary emphasis is on buildings with 120/240 volt electrical systems which include most one- or two-family dwellings and some small commercial establishments . [NFPA 907M-1983]

NFPA 921 - 1992 GUIDE FOR FIRE AND EXPLOSION INVESTIGATIONS This is the first edition of NFPA 921, Guide for Fire and Explosion Investigations. It was developed by the Committee on Fire Investigations to assist in IMPROVING THE FIRE INVESTIGATION PROCESS and the quality of information on fires resulting from the investigative process. The guide is intended for use by both public sector employees who have statutory responsibility for fire investigation and private sector persons conducting investigations for insurance companies or civil litigation. Throughout the development of this document, it has been the goal of the Committee to provide guidance that is BASED ON ACCEPTED SCIENTIFIC PRINCIPLES OR SCIENTIFIC RESEARCH . [NFPA 921-1992]

NINE - ONE - ONE (9-1-1) Enhanced 911, or E911, is an emergency phone system that provides the caller's address, response district, and other important information. When the caller dials 911 to report an emergency, this information automatically appears on the dispatcher's computer screen, along with dispatch information for fire, police, EMS, or other emergency responder. This system is invaluable, especially in those cases where the caller is in an agitated state and may be unable to give information fully or clearly. Such a system, thereby, can have a dramatic effect on reducing response time . [NFPA Handbook 1991]

NONCOMBUSTIBLE CONSTRUCTION means that type construction in which a degree of fire safety is attained by the use of noncombustible materials for structural members and other building assemblies. (Ontario Fire Code 1996)

NONFLAMING COMBUSTION There is another mode of combustion not involving any flame. It is called smoldering, glowing, or nonflaming combustion. The rate of burning during flaming combustion is many times as great as during smoldering combustion . [Friedman 1989]

NON-FLAMMABLE GAS Any material or mixture, in a cylinder or tank, other than poison or flammable gas, having an absolute pressure in the container exceeding 40 psi at 70oF, or having an absolute pressure exceeding 104 psi at 130oF . (49 CFR) HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

 

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OBJECTIVE The desired accomplishment for which a process is undertaken . (Benner 1997)

OBSERVATION A noting and recording of an event or condition / state . (Benner 1997)

OCCUPANCY means the use or intended use of a building or part thereof for the shelter or support of persons, animals or property. (Ontario Fire Code 1996)

OCCUPANT LOAD means the number of persons for which a building or part thereof is designed. (Ontario Fire Code 1996)

OCTANE NUMBER Octane number, a quality rating for Gasoline indicating the ability of the fuel to resist premature detonation and to burn evenly when exposed to heat and pressure in an Internal Combustion Engine. Premature detonation, indicated by knocking and pinging noises, wastes fuel and may cause engine damage. The octane number can be increased by varying the relative amounts of the different Hydrocarbons that make up the gasoline or by additives, e.g., tetraethyl lead. Federal regulations in the U.S. require commercial gasoline pumps to indicate the octane number, which is usually 87 or 89 for regular grade gasoline and 93 for premium grade. Since the early 1970s most Automobiles have been built to operate on low octane gasoline with little or no lead added . (Hydro Cut General Terminology & Resource Information)

ODOR THRESHOLD The lowest concentration in the atmosphere which can be detected by the human sense of smell. Often a poor indicator of toxicity risk . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

OFFICER IN CHARGE The officer is not only in charge of his assigned unit at fires but is the administrative officer in charge of the men, equipment,! and station of his command. Moreover, the establishment of a company officer rank provides the opportunity for specifying higher qualifications and skills than those normally expected of experienced apparatus operators. These skills include both greater understanding of fire protection as well as administrative and management skills. Normally, officer selection is made on the basis of competitive examination with due credit for experience. Unless a chief arrives in time to direct the placement of companies at a fire, much of his value as a fireground coordinator and supervisor is lost. The success with which the work of various fire fighting units are COORDINATED in large measure determines the OVERALL EFFICIENCY obtained with the men and equipment employed . [Kimball 1969]

OHM Ohm, symbol O, unit of electrical Resistance, defined as the resistance to the flow of a steady electric current offered by a column of mercury 14.4521 grams in mass with a length of 1.06300 m and with an invariant cross-sectional area, when at a temperature of 0°C . (Hydro Cut General Terminology & Resource Information)

OIL Any of numerous mineral, vegetable, and synthetic substances and vegetable and animal fats that are generally slippery, combustible, viscous, liquid or liquefiable at room temperature . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

OLFACTORY Pertaining to the sense of smell . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

ONOMATOPOEIA / use of words to imitate natural sounds; accommodation of sound to sense. (A Glossary of Rhetorical Terms with Examples, Ross Scaife)

OPERATIONS That organizational level within the Incident Command System (ICS) immediately subordinate to the Incident Commander. When established, this position is responsible for the direct management of all incident tactical activities. (NIIMS) HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

OPINION A belief held confidently, but reached without positive proof . (Benner 1997)

OPTICS Scientific study of light. Physical optics is concerned with the genesis, nature, and properties of light; physiological optics with the part light plays in vision; and geometrical optics with the geometry involved in the reflection and refraction of light as encountered in the study of the mirror and the lens . (Hydro Cut General Terminology & Resource Information)

ORDER means an order made under subsection 21(1) of the Fire Protection and Prevention Act. (Ontario Fire Code 1996)

ORGANIC CHEMISTRY Organic chemistry, branch of Chemistry dealing with Carbon compounds. Of all the elements, carbon forms the greatest number of different compounds; moreover, compounds that contain carbon are about 100 times more numerous than those that do not. Compounds containing only carbon and Hydrogen are called Hydrocarbons. Organic compounds containing Nitrogen are of great importance to Biochemistry. Organic chemistry is of importance to the petrochemical, pharmaceutical, and textile industries; in textiles a prime concern is the synthesis of new organic molecules and Polymers . (Hydro Cut General Terminology & Resource Information)

ORGANIC PEROXIDE Strong oxidizers which are often chemically unstable, containing the -o-o structure. They react readily with solvents or fuels resulting in an explosion or fire . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

OSHA Occupational Safety and Health Administration. An agency of the Department of Labour in the United States, active in eliminating occupational hazards and promoting employee health and safety . (Hydro Cut General Terminology & Resource Information)

OVERHAUL Fire department procedure of inspecting premises after extinguishment to insure that the fire is completely extinguished and will not rekindle later on, and rendering the fire-damaged premises in a safe condition before returning control over to the owner and/or occupants . ... [Fire Cause Determination, IFSTA 1986]

OVERHAUL Teamwork necessary. Overhaul is closely related to fire extinguishment and salvage operations. It is not a separate or individual FUNCTION to which certain men may be detailed as in salvage operations . (Fire Chief's Handbook, 4e, 1978)

OWNER means any person, firm or corporation having control over any portion of the building or property under consideration and includes the persons in the building or property. (Ontario Fire Code 1996)

OXIDIZER A chemical, other than a blasting agent or explosive, that initiates or promotes combustion in other materials thereby causing fire either of itself or through the release of oxygen or other gases . (49 CFR 173.151) HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

OXIDIZING AGENT A chemical substance that can react with hydrogen or with metals. Examples are oxygen, ozone, nitrate salts, perchlorate salts, and halogens . [Friedman 1989]

OXIDIZING MATERIAL means a material, other than ordinary atmospheres, that by itself is not necessarily combustible, but that may, generally by yielding oxygen, cause or contribute to the combustion of another material. (Ontario Fire Code 1996)

OXYGEN DEFICIENCY A concentration of oxygen insufficient to support life . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

OXYGEN DEFICIENT ATMOSPHERE An atmosphere which contains an oxygen content less than 19.5 % by volume at sea level . HAZARDOUS MATERIALS EMERGENCY RESPONSE GLOSSARY OF STANDARDIZED TERMS, State of California's Chemical Emergency Planning and Response Commission, 1991

OXYMORON / apparent paradox achieved by the juxtaposition of words which seem to contradict one another.
*I must be cruel only to be kind. Shakespeare, Hamlet (A Glossary of Rhetorical Terms with Examples, Ross Scaife)


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