Flashcards in book 83 fire chemistry Deck (44):
Liquids having a flash point at or above 100 degrees F.
Rapid oxidation of a substance accompanied by the release of energy usually in the form of heat and light.
The lowest temperature of a liquid in an open container at which vapors evolve fast enough to support continuous combustion.
The term lower flammable limits (LFL) describes the minimum concentration of vapor -to -air below which propagation will not occur in the presence of an ignition source. The "upper flammable limit" (UFL) is the maximum vapor-to-air concentration above which propagation of flame will not occur.
Liquids having a flash point below 100 degrees F.
The minimum temperature at which a liquid gives off vapors in sufficient concentrations to form an ignitable mixture with air near the surface of the liquid.
A form, of energy associated with the motion of atoms and molecules.
The amount of heat released during the complete oxidation of a substance.
Heat of combustion
The minimum temperature to which a substance must be heated in air in order to initiate or cause combustion, independent of the heating element or source. The ignition temperature of ordinary combustibles is between 300 and 1000 degrees. F
As a substance burns, it mixes with oxygen and produces heat.
The ratio of the weight of a solid or liquid substance to the weight of an equal volume of water.
The quantity of heat concentration. The intensity of heat is measured in degrees (Fahrenheit or Celsius).
The weight per unit volume of a pure gas or vapor. In fire protection, vapor density is reported in terms of the ratio of the relative weight of a volume of vapor to the weight of an equal volume of air under the same conditions of temperature and pressure.
A vapor denisty less than 1.0 indicates a vapor is ____ than air.
A vapor density more than 1.0 indicates a vapor ______ than air.
Heat , fuel, oxygen equals?
The fire triangle
Heat , Fuel , Oxygen and Uninhibited chain reaction among all parts of the ________
The Chemical decomposition of matter through the action of heat.
The transfer of heat from one object to another through direct physical contact.
The transfer of heat by some circulating medium (liquid or gas). This is the form of heat transfer most RESPONSIBLE for fire spread in structural fires.
Example; The spreading of fire from lower to upper structural areas when upper areas become heated to their ignition temperature is ____.
The transfer of heat as energy traveling through space or materials as waves.
example: exposure problems in large fires...
Although actual flame temperatures can reach 1000 degrees F. temperatures in the surrounding area are not greatly increased. There is free burning with open flame. Oxygen in the area remains new 21%. Thermal updrafts causes heat to accumulate at the higher portions of the area.
Incipient phase (growth)
air from surrounding atmosphere is drawn into the fire fire.
Mushrooming may take place and flame is present. Oxygen content of area is usually reduced to 16%-18% Fire gases which may be present are carbon, carbon monoxide, carbon dioxide, water, sulfur dioxide,
Flashover frequently occurs during this phase.
Free burning phase.
Free burning may cease in the fire area. Area fills with dense smoke. Oxygen may drop below 15%. Temperature may reach 1000 degrees F. thought the area. Improper /uncontrolled air admission may result in "backdraft"
A ________ is defined as an explosion or rapid burning of heated fire gases resulting from the introduction of oxygen when air is admitted into a building heavily charged by smoke from a fire which has depleted the oxygen content of a building.
Heavy smoke conditions on arrival
Lack of Visible flame
Improper method of entering a structure may cause a backdraft
Movement of smoke prior to explosion
Structure may appear to breathe
Whistle, jet or train sound
_____ is the stage of the fire when all combustibles in an area have become heated to their ignition temperature, then ignite simultaneously.
Fire resistive, structural elements in Type ___ fire resistive buildings shall be of steel, iron , concrete, or masonry. Walls and permanent partitions shall be of noncombustible fire-resistive construction except that permanent non-bearing partitions may have fire -retardant wood.
Type ____ Noncombustible /fire-resistive , one-hour or no-hour construction.
construction in which walls, partitions, and structural members are of noncombustible material but do not qualify as type 1 fire-resistive
Type _____ Ordinary construction , in which exterior bearing walls or bearing partitions of exterior wall are of noncombustible materials and have a minimum hourly fire-resistive rating. Wood allowed for interior use.
Type ____ heavy timber construction where exterior bearing and non-bearing walls are noncombustible and have a minimum fire-resistive rating of four hours. Colums, beams and girder are commonly heavy timber with wood floors and roof construction built without concealed spaces..
Type ______ Wood frame construction in which exterior walls, bearing walls, partitions, floors and roofs as well as their supports are wholly or partly wood or other combustibles.
The weight of the building and any equipment permanently attached or built-in
Any load other than a dead load. _____ loads vary with intended or actual use of the structure. Examples of common _____ loads ae occupants, storage, and furnishings.
_____loads which are delivered in a short period of time. ______loads may be more harmful when supported as dead or live loads. Examples are explosions, wind and earthquakes.
_____ loads: the total number of BTU's which might be evolved during a fire in the building or area under consideration and the rate at which the heat will be evolved. Occupancy type has a direct relationship to fire load and generally dictates the possible _____ load
Conventional or ordinary construction consists of a ridge board and rafters from the ridge board down to and across the outside walls (studs). Ridge and rafters are usually 2 by6 inches or larger. Rafters are usually 16 inches to 24 inches on center. Additional support is provided by collar beams and ceiling joists. Roofs are constructed in semi-flat to steep pitches.
Similar to gable roof. Ends of roof terminate in hip. Conventional or ordinary construction consist of ride pole and hip rafters rom the ridge board down to and across the corners at the outside walls. valley rafters are utilized where two roof lines are joined together. Ridge and rafters are usually 2 by 6 inches or lager. Rafters are usually 16 to 24 inches on center.
Wood joists (rafters) of various sizes laid across the outside walls or outside walls to interior walls or structural supports Joist may also be suspended by metal hangers. Joist are covered with 1 by 6 inch sheathing or plywood and composition roofing material.
wooden truss members constructed from 2 by 12 inch lumber with sloping ends. Usually a heavy grade construction. Metal tie rods may be used vertically for additional support. Joists are 2 by 6 inches and 2 by 8 inches covered with 1 by 6 inch sheathing and composition roofing mater.
Bridge truss roof
_____ roff with ties rods and turnbuckles offering lateral support. Tie rods with turnbuckles are used below each arch member to support the exterior walls. Tie rods may pass through exterior walls to an outside plate facilitating identification. Tension is maintained by the turnbuckles top chords of arch members may utilize laminated 2 by 12 or larger. Two by 10 inch rafters are covered by 1 by 6 inch sheathing and composition roofing material.
Bowstring are roof
Usually large size (2 by 12, 2 by 14 inch) wooden members utilized to construct truss arch. Some arches have multiple laminated beams to form one arch. Rafters ( 2 by 10 inch or larger) are covered with 1 by 6 inch: sheathing and composition roofing material.
Ribbed ( trussed) arch roof