ISI Investigations
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RADIATION
As used in fire investigation, radiation is one of the three methods or media by which heat is transferred. The three methods being conduction, convection, and radiation. Radiation is the heat transfer, from one body to another, by heat rays, through intervening space, in much the same manner as light is transferred by light rays. Two examples are heat from the sun and heat from an electric heater adjacent to a wall. Radiated heat passes freely through a vacuum and through gases, like light, heat is reflected from glass or another bright surface.
SABOTAGE
The damaging of property or hindering of production in an underhanded effort to defeat or harm persons or property.
SEARCH PATTERN
The method used by the Accelerant Detetion Canine Team to cover a complete area when searching for accelerants.
SELF-INCRIMINATION
The giving of testimony as a witness against one's will. The United States Constitution provides the Fifth Amendment guaranteeing that no one shall be compelled to testify against himself in the Federal courts and nearly every state has embodied the same provisions in their respective constitutions. The guarantee extends to self incrimination situations during interviews by peace officers and certain governmental representatives.
SMOKE
The vaporous matter resulting from some forms of combustion and made visible by minute particles of carbon suspended in the vapor. In chemistry, suspension of solid particles in gas. Under the usual conditions of insufficient oxygen for complete combustion, there may also be present methane, methanol, formaldehyde, and formic and acetic acids. The combination of the combustible, rate of heating, oxygen concentration at or near the combustible surface, along with temperatures, usually determines the composition of fire gases and the resulting smoke, if any. The color of the smoke may vary with the composition of the combustibles and by ventilation or application of water.
Smoke particles may cool to the extent where water vapor, acids, and residues of the combustibles involved may be identified if recovered from areas such as windows or other surfaces. It is, of course, well established that moisture laden particles, if inhaled, may carry highly poisonous or irritating compounds into the respiratory tract and eyes. If allowed to accumulate in a building, hot unburned products of combustion will ignite explosively when a supply of oxygen is suddenly made available. (See Flashover) Some firemen and investigators call this phenomenon a smoke explosion. This is one of the prime reasons why firemen vent fires, usually by opening windows, doors, or by cutting holes in the roof.
SMOKE STAINING
Smoke particles will adhere to unburned surfaces such as walls and windows within a burned structure. Smoke staining assists the investigator in determining whether the fire spread was rapid or slow and whether accelerants were burned.
SPECIFIC GRAVITY
The ratio of the weight or mass of the given volume of a substance to that of an equal volume of another substance used as a standard. (Water for liquids and solids, air or hydrogen for gases) The specific gravity of gasoline and other petroleum products, for example is commonly measured in Degrees API (American Petroleum Institute.)
SPECIFIC HEAT
The ratio of the amount of heat required to raise the temperature of a unit mass of a substance one degree to the amount of heat required to raise the temperature of the same mass of water one degree; the number of calories required to raise the temperature of one gram of a given substance one degree Centigrade.
STATIC ELECTRICITY
Designed as stationary electrical charges or discharges in the atmosphere; frictional electricity such as produced in movement of bodies or fabrics on surfaces. It is relevant to fire investigation in that electrical charges, without proper bonding or grounding, may introduce a spark or arc into an explosive or combustible environment. Some examples are improperly bonded or grounded fuel lines, tanks, and pumping facilities.
SUBROGATION
As used in civil actions, the substitution of one for another so that the new party succeeds to the former's rights or legal claims. It is frequently referred to as the doctrine of substitution. It is a device commonly used in insurance litigation, adopted or invented by equity to compel the ultimate discharge of a debt or obligation. It is the mechanism by which the equity of one man (or party) is worked through the rights of another. The right of an insurer on payment of a loss to be subrogated pro tanto to any right of action which the insured may have had against any third person whose wrongful act or neglect caused the loss insured against by the insurer is one example.
TEMPERATURE
The degree of hotness or coldness of any substance or body, usually measured in terms of Kelvin or Rankine temperature.
THERMOSTAT
Thermostats are widely used, fixed temperature heat detectors used in signaling systems. Probably the most common type is the bimetallic type which utilizes two metals with different expansion coefficients resulting in movement of the strip and closing or opening of the contacts regulated to the temperature function.
TORT
An injury or wrong committed either with or without force, to a person or person's property. Such injury may arise out of nonfeasance, malfeasance, or misfeasance.
TRAILER
A term used to describe the means utilized to extend an ignition point from a location outside an occupancy into the space where the plant or booster may be located. Trailers often connect various "plants" or "sets" inside a space to insure complete involvement within a short period of time. Flammable liquids such as kerosene and charcoal lighter fluid have been frequently used. Gasoline is seldom used as a trailer because of the rapid evaporation characteristics that makes its use unpredictable. Various types of window cord, rope and newspaper have been commonly used, saturated in kerosene or other medium flashpoint fuels and distributed through the premises. Blasting cord has been used, particularly where explosions are desired.
TRANSFORMER
Generally, an apparatus or device for transforming or converting the voltage of an electric current. There are two types; a step down transformer which changes high voltage to lower voltage; and a step up transformer which changes lower voltage to higher voltage. Transformers vary in size and capacity from the liquid and mechanically cooled types found in substations and primary facilities right on down to the smaller units in primary service entrances and secondary areas.
VAPOR DENSITY
Vapor density is the relative density of a gas or vapor (minus air) as compared to air. A figure of less than 1 indicates that a vapor is lighter than air; a figure greater than 1 indicates that the vapor is heavier than air. The vapor density of a compound equals the molecular weight of the compound divided by 29. In the formula, 29 is the composite of the molecular weight of air.
VAPOR PRESSURE
The pressure of a confined vapor that has accumulated above its liquid. It is determined by the nature of the liquid and the temperature. Vapor pressure figures for many substances may be found in chemical handbooks; vapor pressures of petroleum products are usually determined by the Reid method as recommended by the American Society for Testing Materials. ASTM Standard D 323
VENTING
Firemen usually vent fires by opening doors or windows or cutting holes in the roof. The reason for this is to allow gases and hot unburned products of combustion to escape. If this is not done, smoke explosions or flashover may occur.
VOIR DIRE
To speak the truth. An oath is so called when it is administered to a prospective juryman or a witness as a preliminary step to examining his qualifications as a juror or witness.
VOLATILE
Those that may be readily vaporized. The hazards depend upon their flash point and explosive range. Examples of volatile liquids are acetone, allyl alcohol, ethyl alcohol, gasoline, and kerosene.
VOLT (V)
Volt is a unit of electrical pressure, the force which causes electricity to flow through a conductor. Voltage is not necessarily a measure of fire hazard. For example, 1.5 volts through a very fine wire can cause that wire to become red hot. The heat of the wire, if in contact with combustibles, will result in fire.
WATT
The watt is a unit of electrical power. A current of one ampere flowing under pressure of one volt equals one watt. For example, a 100 watt light bulb rated at 110v takes a current of 0.9 amp and has a resistance of 130 ohms. It is the demand for power when using items such as a light bulb, heaters, stoves, and motors that places the load on the conductors. If the demand is more than the size or capacity the conductors can carry (are rated for), heating of the conductors will follow. A fire may follow the heating or arcing growing out of the overload since circuit safety devices, such as fuses or circuit breakers may not open the circuit before ignition of combustibles occurs.
