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JATC STEP 1A questions with complete solutions
JATC STEP 1A questions with complete solutions
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JATC STEP 1A questions with completesolutions
Backdraft - correct answer ✔✔The explosive burning of heated gases that occurs when oxygen is
introduced into a compartment has a high concentration of flammable gases and a depleted supply of
oxygen due to an existing fire. An increase in low-level ventilation prior to upper level ventilation can
result in a backdraft. Signs of backdraft indicators include blackened windows, turbulent smoke, rapid
airflow, "puffing" of smoke, etc. The best tactic to prevent backdraft is to vertically ventilate above the
fire.
Flashover - correct answer ✔✔A rapid transition from the growth stage to the fully developed stage.
When flashover occurs, combustible materials in the compartment and gases produced by pyrolysis
ignite almost simultaneously; the result is full-room involvement. During flashover, volume of fire can
increase from 1/4th of room to entire room.
-Two significant factors for flashover progression:
-Sufficient fuel and heat release rate
-Ventilation/Oxygen
Smoke Explosion - correct answer ✔✔Form of fire gas ignition; the ignition of accumulated flammable
products of combustion and air that are within their flammable range
Rollover - correct answer ✔✔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 or across the ceiling. May
indicator flashover conditions.
Dead Load - correct answer ✔✔Weight of the building itself and any equipment permanently attached
to it or built in. AKA Self Weight.
-A structure's dead load is often increased during alteration of a building. Added dead loads for which
the building has not been designed can be deadly. Examples: air conditioning units, additional trusses,
renovations to roof, etc.
, Live Load - correct answer ✔✔Live loads are any loads other than dead loads. Loads that are movable:
Water, snow, safes, firefighters, etc. Water and snow are significant collapse factors, especially when
added to a roof. Additionally FF efforts can cause building to collapse due to added weight of water.
Impact Load - correct answer ✔✔Impact loads are loads that are delivered in a short time. Crashes, fires,
explosions, collapse of structures, weight of equipment/FF placed on structure, falling trees, etc. Added
stress to a building that is under attack by fire is very dangerous. There is no such thing as no impact
load. Any stress can lead to added collapse potential. Lateral impact loads can produce disastrously high
stresses.
Describe the special considerations to firefighting that come with construction using steel beams and
members. - correct answer ✔✔During a fire, it is essential to determine how long steel members have
been exposed to heat. Critical temperature for steel is 1000 degrees F. This temp can easily be reached at
ceiling level from rising heat and smoke. Elongating steel can push out load-bearing walls and cause
collapse. If the walls are able to withstand the elongation, the steel will fail and sag somewhere in the
middle, causing collapse of upper floors or roof. A 50ft steel beam can elongate as much as 4 inches.
Water can cool steel structural members and stop elongation, which reduces the risk of a structural
collapse. Lightweight steel truss will fail much quicker than a large, heavy I-beam.
List the factors that should be considered when trying to determine the potential for structural collapse.
CACAL-SLAW - correct answer ✔✔1. Construction type
-Lightweight construction
2. Length of time fire burns
-The longer a fire burns, the greater the temperature of the fire gases in the upper levels of the structure
or compartment
3. Stage of the fire
-Collapse not likely in incipient stage. Collapse potential increases as stage of fire increases
4. Contents
3 ways:
-Contents may generate higher temperatures and rapid combustion due to higher fuel load
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