Chapter 14 Flashcards
The ISO’s key responsibility is to recognize incident hazards and make corrective recommendations to prevent injuries to responders.
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The ISO must check in with the IC and, after receiving a briefing, conduct an independent 360 degree assessment of the incident.
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High humidity can cause smoke to remain close to the ground, obscuring visibility of the building.
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The ISO must continuously monitor wind velocity and direction to ensure personnel and hose streams are not placed in a windward position.
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Generally, wind speeds greater than 20 mph will reduce aerial ladder load capacity.
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Personnel operating at a scene with high intensity activity must be provided proper work/rest periods and follow the recommendations in NFPA 1584, standard on the rehabilitation process for members during emergency operations and training exercises.
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Cardiac related events at emergency incidents are a leading cause of firefighter illness and death.
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It is critical that medical surveillance monitoring and proper rehabilitation is established at emergency and planned events.
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High noise levels can also lead to a condition called tunnel hearing.
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Tunnel hearing can cause people to concentrate so closely on one task that they lose their sense of situational awareness.
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Longer shifts equate to lessened situational awareness, which increases the risk of injury.
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Research shows that fires go through four distinct stages: incipient, growth, fully developed, and decay.
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ISOs should assume that an entire structure is the compartment that fire is affecting rather than just the compartment of origin.
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Open interior doors, hallways, and stairwells connecting rooms extend the possible growth potential of a fire beyond its compartment of origin.
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At a fire scene, the stages of fire development are a guide for what could occur during the fire but are not a pattern of what will occur every time.
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The ISO should forecast fire spread based on fire department suppression efforts and conduct an ongoing assessment of hazards as they relate to the stages of fire growth.
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The type of fuel involved in combustion affects the heat release rate.
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Fires involving class B and C fuels will eventually spread to the building contents and structure, resulting in a primarily class A fueled fire.
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In a compartment fire, surface to mass ratio is one of the most fundamental class A fuel characteristics influencing fire development.
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Combustible materials with high surface to mass ratios are much more easily ignited and will burn more quickly than the same substance with less surface area.
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Fires involving class B flammable/combustible liquids will be influenced by the surface area and type of fuel involved.
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A liquid fuel spill will increase that liquid’s surface to volume ratio generating more flammable vapors than the same liquid in an open container.
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Burning synthetic fuels produces products of combustion that contain large quantities of solid and liquid particulates and unburned gases.
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Heat release rate - total amount of heat produced or released to the atmosphere from the convective lift phase of a fire, per unit of mass of fuel consumed per unit time.
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Just like with solids, an increase in a liquid’s surface area correlates to the generation of more flammable vapors.
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A compartment fire that results from a flammable/combustible gas leak may begin with a rapid ignition of the gas and an explosion.
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Factors that influence the availability and location of additional fuels include the building configuration, construction materials, contents, and proximity of the initial fire to these exposed fuel sources.
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In buildings where the construction materials are flammable, the materials themselves add to the structure’s fuel load.
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Plywood is easily ignited, even while level and horizontal, because it has a high surface to mass ratio.
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The contents of a structure are often the most readily available fuel source, significantly influencing fire development in a compartment fire.
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When contents rapidly release a large amount of heat, both the intensity of the fire and speed of development will be increased.
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Polyurethane foam has a high surface to mass ratio and will continue to burn after it has liquefied.
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Pyrolize - description of the process of a solid beginning to emit gases due to heat exposure.
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Fuels located in the upper level of adjacent compartments will pyrolize more quickly from the effect of the hot gas layer.
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Residential structures built after 1990 burn hotter, faster, and produce more smoke with flammable properties than traditional or legacy construction.
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Slower fire development is due to the greater volume of air and the increased distance radiated heat must travel from the fire to the contents that must be heated.
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A large volume of air will support the development of a larger fire before the lack of ventilation becomes the limiting factors.
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Ventilation in a compartment significantly influences how fire develops and spreads.
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When sufficient oxygen is available, the characteristics and configuration of the fuel control fire development, Under these conditions, the fire is said to be fuel-controlled.
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Fuel controlled - A fire with adequate oxygen in which the heat release rate and growth rate are determined by the characteristics of the fuel, such as quantity and geometry.
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Ventilation controlled - Fire with limited ventilation in which the heat release rate and growth is limited by the amount of oxygen available to the fire.
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When the available air supply begins to limit fire development in a compartment fire, the fire is said to be ventilation controlled.
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When a fire becomes ventilation controlled, the available supply will determine the speed and extent of fire development and the direction of fire travel.
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When considering fire development, personnel should consider potential openings that could change the ventilation profile under fire conditions.
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Bi direction flow paths, sometimes created by the task ventilation, can be deadly to firefighters and civilians inside the structure.
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When the fire becomes ventilation controlled, the fire’s HRR will decrease.
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Heat reflectivity - increases fire spread through the transfer of radiant heat from wall surfaces to adjacent fuel sources.
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Retention - maintains temperature by slowly absorbing and releasing large amounts of heat.
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Ambient conditions, such as high humidity and cold temperatures, can slow the natural movement of smoke.
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If a window fails or a door is opened on the windward side of a structure, fire intensity and spread can increase significantly, creating a blowtorch effect.
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A compartment’s thermal properties contribute to the accumulation of heat.
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Cold temperatures can cause smoke to appear white and give a false impression of the interior conditions based upon the color of smoke.
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Atmospheric air pressure can also cause smoke to remain close to the ground, obscuring visibility during size up.
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A ceiling jet convects heat through the ceiling, which in turn radiates heat back down toward the room some distance away.
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Unconfined fires draw air from all sides and the entrainment of air cools the plume of hot gases, reducing flame length and vertical extension.
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When the fuel package is not in the middle of the room, the combustion zone expands vertically.
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The expanded combustion zone increases both the temperatures in the developing hot gas layer at ceiling level and the spread of the ceiling jet.
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The thermal layering of gases, sometimes referred to as heat stratification and thermal balance, is the tendency of gases to form into layers according to temperature.
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Changes in ventilation and flow path can significantly alter the thermal layering.
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As the volume and temperature of the hot gas layer increases, so does the pressure.
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The interface of the hot and cooler gas layers at the opening is commonly referred to as the neutral plane because the pressure is neutral where the layers meet.
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The neutral plane will lower as the fire burns the available fuel in the compartment.
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During the development of a compartment fire, pyrolysis of exposed fuels can produce combustible gases, which can gather at locations in the layer some distance away from the fire plume.
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Radiated heat from a fire can pyrolize nearby materials.
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Use effective fire control and ventilation tactics to raise the position of the hot gas layer.
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As the fire moves through the growth stage and becomes ventilation controlled, isolated flames may be observed moving through the hot gas layer.
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Rapid transition from the growth stage to the fully developed stage is known as flashover.
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Most fires that develop beyond the incipient stage become ventilation controlled.
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Under laboratory conditions or when fire is fuel controlled, flashover occurs during the growth stage.
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The fully developed stage occurs when all combustible materials in the compartment are burning.
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Increases in the available air supply will result in higher heat release.
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A compartment fire will decay as the fuel is consumed or if the oxygen concentration falls to the point that flaming combustion is diminished.
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As the fire consumes the available fuel in the compartment and the heat release rate begins to decline, it enters the decay stage.
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If there is adequate ventilation, the fire becomes fuel controlled.
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When a compartment fire enters the decay stage due to a lack of oxygen, the rate of release also declines.
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When a flashover occurs, the combustible materials in the compartment and fuel gases ignite almost simultaneously, resulting in full room involvement.
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Flashover typically occurs during the growth stage of a fire but may occur in the fully developed stage.
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During flashover, the volume of the fire can increase from approximately 1/4 to 1/2 of the room’s upper volume filling the entire volume of the room and potentially extending out of any openings in the room.
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Regardless of the type, quantity, or configuration of fuel, heat release is dependent on oxygen.
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While no exact temperature is associated with flashover, it typically occurs at 1,100*F ceiling temperature.
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Rollover describes a condition where the unburned fire gases that have accumulated at the top of a compartment ignite and flames propagate through the hot gas layer across the ceiling.
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Rollover may occur during the growth stage as the hot gas layer forms at the ceiling of the compartment.
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A ventilation controlled compartment fire can produce a large volume of flammable smoke and other gases due to incomplete combustion.
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An increase in low level ventilation prior to upper level ventilation can result in an explosively rapid combustion of the flammable gases, called backdraft.
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Backdraft occurs in the decay stage, in a space containing a high concentration of heated flammable gases that lack sufficient oxygen for flaming combustion.
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A smoke explosion may occur before or after the decay stage.
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Smoke explosions are violent because they involve premixed fuel and oxygen.
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Fire is controlled and extinguished by limiting or interrupting one or more of the essential elements in the combustion process.
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Cooling low flashpoint flammable liquid with water cannot sufficiently reduce vapor production.
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Water absorbs significant heat as its temperature is raised, but it has its greatest effect when it is vaporized into steam.
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When water is converted to steam at 212*F, it expands approximately 1,700 times.
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Firefighters can control steam production by: using good nozzle technique, applying the appropriate amount of water, applying water using the most effective form.
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The simplest method of fuel removal is to allow a fire to burn until all fuel is consumed.
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Reducing the oxygen available to the combustion process reduces a fire’s growth and may extinguish it over time.
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Flooding an area with an inert gas, such as carbon dioxide, displaces oxygen and disrupts the combustion process.
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Door control - firefighting tactic intended to reduce available oxygen to a fire and create a controlled slow path in a structure for tactical ventilation, firefighter survivability, and occupant survivability.
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Blanketing foam prevents oxygen from mixing with fuel gases which in turn inhibits the combustion process.
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Unplanned ventilation can result from wind outside the structure.
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Wind can affect ventilation operations and may also create a pressure differential between the interior and exterior pressures which causes windows to fail.
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Tactical ventilation is the planned, systematic, and coordinated introduction of air and removal of hot gases and smoke from a building.
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Increased ventilation to a ventilation controlled fire will quickly result in an increase in the heat release rate.
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Even with coordinated tactical ventilation, there will be an increase in the combustion rate when the fire is ventilation controlled.
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Smoke volume is the quantity of smoke visible.
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Volume pushed smoke will usually flow neither smooth nor turbulent.
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High neutral plane may indicate that the fire is in the early stages of development.
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Mid-level neutral plane could indicate that the compartment has not ventilated yet and that flashover is approaching.
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Very low level neutral plane may indicate that the fire is reaching backdraft conditions.
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There are three ways to describe how smoke moves: floating or hanging, volume pushed, and heat pushed.
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The heat within the smoke will dictate speed.
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Floating smoke is the same temp as the air around it and is often found in air conditioned buildings or fires that are sprinkler controlled.
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Floating or hanging smoke will move according to air currents and indicates a small, early stage fire, mostly containing moisture from the first stage of pyrolysis.
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Fast exiting smoke indicates a large fire and or a high rate of fire spread.
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If the fire is under-ventilated, pressurization can reduce flame action.
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Turbulent black smoke has lots of particles and, indicative of vent controlled smoke, has heat.
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Laminar/straight line smoke that is thin and fast moving is heat pushed, not under ventilated, and is exiting from opening near active flaming fire.
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Smoke color and location are possible indicators of the location of the fire, its intensity, and possibly the fuel being consumed.
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Tar, soot, and carbon are the most common heated particles found in smoke, giving it the black color.
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Moisture and heated gases give the smoke its white color.
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Light white smoke indicates that pyrolysis is occurring in areas adjacent to the main body of fire.
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When a product is heated at a consistent temp, it can pyrolize and release types of flammable gases.
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Brown smoke is common in mid-stage heating as moisture mixes with gases and carbon as pyrolysis increases.
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Caramel colored smoke usually indicates clean wood burning, such as a fire involving structural wood members.
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Gray smoke indicates a combination of mixing smoke colors.
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Black smoke contains high quantities of carbon particles and is an indicator of the amount of ventilation available at the seat of fire.
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The darker and more turbulent the smoke is, the closer you are to a rapid fire event.
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The denser the smoke, the lower the visibility, and the more likely that heat build up indicates a pending flashover.
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Thin black smoke is the direct result of heat from a flame.
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The term black fire refers to a dark black, thick, turbulent smoke that is ready to ignite.
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When black fire is present, applying water to cool the ceiling area is encouraged in an effort to reduce the potential for a flashover.
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Flow path is the movement of fresh air toward the base of a fire and the movement of smoke and heated gases out of a structure, understanding this phenomenon can help in the ventilation of a fire.
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Heat is a form of energy transferred from one body to another as a result of a temperature difference.
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Double paned windows resist failure due to heat, however, the interior pane may be cracked due to heat.
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Blistered paint indicates both extreme temperature and location of the neutral plane.
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Flame color is usually an indicator of the oxygen supply and the extent of fuel-oxygen pre-mixing, which determines the rate of combustion.
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Fire growth requires sufficient oxygen, and flames will naturally seek out the path of least resistance toward the available oxygen.
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Type 1, fire resistive, construction provides the highest level of protection from fire development and spread as well as collapse.
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Fire resistance is required to be 3 to 4 hours depending on the component.
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Reinforced concrete and precast concrete along with protected steel frame construction meet the criteria for type 1 construction.
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Type 2 construction is normally used when fire risk is expected to be low or when fire suppression and detection systems are designed to meet the fuel load of the contents.
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Type 3 ordinary construction is commonly found in churches, schools, mercantile buildings, and residential structures.
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Type IV construction, heavy timber, is characterized by the use of large dimensional lumber.
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Type V construction is commonly known as wood frame or stick frame.
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NFPA 501, standard on manufactured housing, addresses criteria for manufactured homes.
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Manufactured homes are the most common type of factory built homes, almost completely prefabricated prior to delivery, and the least expensive.
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Current estimates indicate that manufactured homes make up 25 percent of all housing sales in the U.S.
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Manufactured homes built before 1976 have less fire resistance than those of current construction.
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NFPA analysis of fires in residential occupancies indicates a steady decline in fires in manufactured homes since 1980.
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Only about 6 percent of all factory built housing starts are modular homes.
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Almost 1 million residential roof structures were constructed utilizing fire retardant plywood sheathing, these roofs disintegrate rapidly and only had a maximum 10 year lifespan.
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Laminate beams - structural members created from layers of composite plywood or OSB.
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It is estimated that more than 60 percent of roof systems are constructed using a truss system.
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Bowstring trusses apply outward pressure to exterior walls, which could contribute to collapse under fire conditions.
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Rain roof - second roof constructed over an existing roof.
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Protected and non-protected lightweight construction assemblies fail much faster than legacy construction assemblies.
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Temperatures at the bottom of basement stairs were often higher than those encountered at the top of the stairs.
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In 10 minutes, a master stream delivering 250 gallons per minutes can add approximately 10 tons of weight to the structural components.
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The size up assessment should provide critical decision making information about the access and egress points available.
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Thermal and photovoltaic are two types of solar power systems that fire and emergency personnel are most likely to encounter.
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Treat the solar power system and panels as Class C fire.
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Knowing the construction material and how fire affects the materials will assist in the risk benefit analysis.
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Every gallon of water that is used to suppress the fire adds approximately 8 pounds of weight to floors that may already be weakened.
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Natural gas is an odorless gas that is lighter than air.
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If natural gas is leaking from an underground line, fire crews should use a fog stream to disperse the concentration of gas at the site and reduce the chance of an explosion.
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Propane, an odorless gas that is heavier than air, is transported by railcar and tanker truck.
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OSHA defines a pressurized vessel as one which operates above 15 pounds per square inch gauge.
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The boundary between wildland areas and residential growth has become known as a wildland urban interface.
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All firefighting personnel with the potential for wildland response should seek formal training resulting in national wildfire coordinating group red card certification.
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Fire can grow and spread rapidly through the upper portions of trees in what are known as crowning fires.
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In hot and dry conditions, vegetation will have little moisture content and ignite easily, which will cause rapid fire growth even with low winds.
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Weather and wind conditions should be assessed prior to initiating wildland fire suppression activities.
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Weather, wind, fuel, and topography play a part in the blowup potential.
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Flaring is a short lived, high intensity fire in a small area.
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Flaring can cause spot fires and be a good indicator of the potential for a blowup.
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The position of advanced warning devices should take into account several factors, such as weather, day/night, topography, and roadway speed.
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A vapor suppressant can be applied to gasoline or diesel to reduce the risk of fire.
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Apparatus and personnel should be downhill of the main body of fire as wildland fires move uphill faster than on flat terrain or downhill.
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