KU Fire 1 Exam Review

What are the four components of the fire tetrahedron?

Oxygen, fuel, heat, and a self-sustained chemical chain reaction.

What is the definition of flashpoint?

The minimum temperature at which a liquid gives off sufficient vapors to ignite, but not sustain combustion, when exposed to an ignition source.

What is the definition of ignition temperature?

The minimum temperature to which a fuel in the air must be heated in order to start self-sustained combustion without a separate spark or flame.

What is the difference between piloted ignition and autoignition?

Piloted ignition requires an external spark or flame; autoignition occurs purely from heat without an external flame source.

Which gas is a byproduct of combustion and binds to hemoglobin faster than oxygen?

Carbon Monoxide (CO).

What are the three methods of heat transfer?

Conduction, convection, and radiation.

How does radiation transfer heat?

Through electromagnetic waves travelling in a straight line through space until they hit an object.

What type of heat transfer occurs through a circulating medium like air or liquid?

Convection.

What is a Class A fire?

A fire involving ordinary combustibles such as wood, cloth, paper, rubber, and plastics.

What is a Class B fire?

A fire involving flammable or combustible liquids, gases, greases, and similar materials.

What is a Class C fire?

A fire involving energized electrical equipment.

What is a Class D fire?

A fire involving combustible metals such as magnesium, titanium, zirconium, sodium, and potassium.

What is a Class K fire?

A fire involving combustible cooking media such as vegetable oils, animal fats, or greases in commercial cooking equipment.

What is the definition of pyrolysis?

The chemical decomposition of a solid fuel material through the application of heat, prior to actual combustion.

What are the stages of fire development?

Incipient, growth, fully developed, and decay.

What occurs during the flashover stage of a fire?

A rapid transition where all the combustible contents and gases in a compartment simultaneously ignite.

What are the warning signs of an impending flashover?

Rapidly lowering smoke layer, high heat build-up, and isolated flames dancing in the smoke layer (rollover).

What is a backdraft?

An explosive ignition of accumulated hot fire gases when oxygen is suddenly introduced into an oxygen-depleted, superheated space.

What are the structural and smoke indicators of a potential backdraft?

Yellowish-brown dense smoke, puffing/pulsing smoke (breathing building), smoke-stained or vibrating window glass, and little or no visible flame.

How does a thermal layer form in a compartment fire?

Through thermal layering (buoyancy), where the hottest gases rise to the ceiling and cooler air sinks to the floor.

What is isolated flame or 'rollover'?

Unburned fire gases at the top of a compartment ignite and burn across the ceiling level.

What is the lower explosive limit (LEL)?

The minimum concentration of fuel vapor in the air that will support combustion; anything below this is 'too lean'.

What is the upper explosive limit (UEL)?

The maximum concentration of fuel vapor in the air that will support combustion; anything above this is 'too rich'.

What happens if a fuel-air mixture is 'too lean' to burn?

There is too much air and not enough fuel vapor to ignite.

What happens if a fuel-air mixture is 'too rich' to burn?

There is too much fuel vapor and not enough oxygen to ignite.

How does surface-area-to-mass ratio affect solid fuel ignition?

A higher surface-area-to-mass ratio (like wood shavings vs. a log) allows the fuel to heat up, pyrolyze, and ignite much faster.

What is the primary extinguishing mechanism of water?

Cooling (absorbing heat from the fire).

What is an endothermic reaction?

A chemical reaction or process that absorbs heat energy.

What is an exothermic reaction?

A chemical reaction or process that releases heat energy.

How does oxygen concentration impact fire intensity and growth?

Normal air is 21% oxygen; lower concentrations slow or stop flaming combustion, while enriched environments wildly accelerate fire growth.

What NFPA standard establishes requirements for structural firefighting PPE?

NFPA 1971.

What are the three layers of a structural firefighting turnout coat?

Outer shell, moisture barrier, and thermal liner.

What is the purpose of the moisture barrier in structural turnout gear?

It prevents the transfer of hot liquids, water, and bloodborne pathogens to the skin while remaining breathable.

How often should structural firefighting PPE be inspected?

Routinely after every use/shift change, and formally at least twice a year.

What does PASS stand for in reference to safety devices?

Personal Alert Safety System.

What triggers a PASS device to sound an alarm?

Lack of motion for 30 seconds (pre-alarm at 20 seconds), or manual activation by the firefighter.

What NFPA standard regulates Self-Contained Breathing Apparatus (SCBA)?

NFPA 1981.

What are the two types of SCBA air-supply systems?

Open-circuit (exhaled air goes into the atmosphere) and closed-circuit (exhaled air is scrubbed and re-breathed).

What type of SCBA system is used exclusively in structural firefighting?

Open-circuit, positive-pressure SCBA systems.

At what percentage of cylinder capacity should an SCBA bottle be replaced?

Below 90% of maximum rated cylinder pressure.

What is the purpose of the SCBA regulator?

It reduces the high pressure from the cylinder down to a safe, breathable pressure just above atmospheric pressure.

What is the purpose of the SCBA bypass/purge valve?

It allows air to bypass the regular mechanics and flow directly into the mask if the main regulator fails.

What does the HUD (Heads-Up Display) inside an SCBA mask show?

Visual lights indicating the remaining air supply in the cylinder.

When does the SCBA low-air alarm sound?

When the cylinder drops to 35% of its rated capacity.

What is the primary limitation of a firefighter wearing an SCBA?

Increased weight, physical fatigue, and reduced visibility/mobility.

How often must an SCBA facepiece be fit-tested?

Annually (at least once every 12 months).

What is hydrostatic testing, and how often is it required for composite SCBA cylinders?

High-pressure water testing to verify cylinder integrity; required every 3 or 5 years depending on the cylinder material (5 years for carbon-fiber).

What should you do if your SCBA malfunctions inside a burning structure?

Stay calm, activate the bypass valve if needed, call a Mayday, and exit the building immediately with your partner.

What is the proper technique for cleaning an SCBA facepiece?

Wash with mild soap and warm water, rinse thoroughly, and air dry (do not use harsh chemicals or paper towels).

What type of protection does a fire shelter provide for wildland firefighters?

It reflects radiant heat and traps breathable air, protecting against burn injuries during a fire entrapment.

What is the definition of an IDLH atmosphere?

Immediately Dangerous to Life or Health.

Name two toxic gases commonly found in structure fires besides carbon monoxide.

Hydrogen Cyanide (HCN) and Phosgene.

What is the dangerous physiological effect of Hydrogen Cyanide (HCN)?

It acts as a chemical asphyxiant by blocking cells from utilizing oxygen at the cellular level.

How do you perform a positive pressure check on an SCBA mask?

Block the exhalation valve with your palm and gently exhale to check if the mask pushes slightly away from your face without leaking air.

How do you perform a negative pressure check on an SCBA mask?

Block the regulator intake with your hand, inhale gently, and ensure the mask collapses flat against your face and holds the vacuum.

What is the maximum time allowed for a firefighter to don turnout gear and SCBA?

Typically 60 seconds (1 minute) according to NFPA and training performance standards.

Why shouldn't you wear synthetic materials like nylon under turnout gear?

Synthetic fabrics melt under high heat and fuse directly to your skin, causing severe burns.

What is the purpose of the physical protection layer on an SCBA cylinder?

To prevent deep cuts, abrasions, and structural weakness to the composite wrap material.

How does heat stress affect a firefighter wearing full PPE?

Turnout gear traps metabolic body heat, leading to rapid dehydration, elevated heart rates, and heat exhaustion.

When can a firefighter safely remove their SCBA during overhaul?

Only after atmospheric air testing proves the air is free of toxic gases, particulates, and carbon monoxide.

What does the acronym PASS stand for when operating a fire extinguisher?

Pull the pin, Aim the nozzle, Squeeze the handle, Sweep the base of the fire.

How are Class A fire extinguishers rated?

Numerically based on the amount of water they hold and the volume of wood/excelsior fire they can extinguish (1-A to 40-A).

How are Class B fire extinguishers rated?

Numerically based on the approximate square foot area of a flammable liquid fire that a non-expert can safely extinguish (1-B to 640-B).

What type of extinguishing agent is commonly used in Class C fires?

Non-conductive agents such as Carbon Dioxide (CO2), clean agents, or dry chemicals.

Why should you never use water on a Class D fire?

Combustible metals react violently with water, causing rapid steam explosions and severe chemical flare-ups.

What type of agent is found in a Class K extinguisher?

A wet chemical potassium-acetate based solution that cools and creates a soapy blanket (saponification).

How does a dry chemical extinguisher extinguish a fire?

It interrupts the chemical chain reaction of the fire tetrahedron.

How does a carbon dioxide (CO2) extinguisher work?

It displaces oxygen and cools the burning fuel.

What is the main hazard of using a CO2 extinguisher in a confined space?

Asphyxiation due to the rapid displacement of oxygen.

What type of fire extinguisher is best suited for ordinary combustibles?

Stored-pressure water extinguishers (Class A).

How far away should you stand when initiating the discharge of a portable extinguisher?

Approximately 6 to 8 feet away from the fire.

What classification symbol is a green triangle?

Class A (Ordinary Combustibles).

What classification symbol is a red square?

Class B (Flammable Liquids).

What classification symbol is a blue circle?

Class C (Electrical Equipment).

What classification symbol is a yellow star?

Class D (Combustible Metals).

What is the difference between life-safety rope and utility rope?

Life-safety rope is used exclusively to support people; utility rope is used for hoisting tools, securing objects, and stability.

What type of rope construction is required for life-safety applications?

Block creel kernmantle construction using continuous synthetic filaments.

What percentage of strength does a knot typically reduce in a rope?

Between 20% to 50%, depending on the type of knot tied.

What is the 'working end' of a rope?

The part of the rope used actively to tie the actual knot.

What is the 'running part' of a rope?

The long, free portion of the rope used for hoisting or pulling.

What is the 'standing part' of a rope?

The section of rope between the working end and the running part.

Which knot is used to form a secure loop that will not constrict?

The Bowline knot.

What is the purpose of a clove hitch?

To securely fasten a rope around a cylindrical object like a pike pole, axe, or post.

What is a half-hitch used for?

As a secondary addition to secure and stabilize long tools when they are being hoisted.

Which knot is used to join two ropes of unequal diameters together?

The Becket bend (sheet bend).

What is a safety knot (or overhand knot) used for?

To prevent the loose working end of a rope from slipping back through the primary knot.

How should ropes be dried after being cleaned?

Suspended loosely or air-dried out of direct sunlight (never dry in a commercial heat dryer).

What is a rope log used for?

To record the service history, dates of use, inspections, and any incident/load stresses applied to life-safety ropes.

What is the beam of a ladder?

The main structural side member that holds and supports the rungs.

What are the rungs of a ladder?

The cross-members that provide footsteps for climbing.

What is the fly section of an extension ladder?

The upper section(s) of an extension ladder that move up and down to extend the height.

What is the bed section of an extension ladder?

The bottom or base structural section that remains fixed in place on the ground.

What are the halyard and pawls (dogs) on an extension ladder?

The halyard is the rope used to raise the fly section; pawls (dogs) are mechanical locking hooks that catch rungs to keep the fly section extended.

What is the proper climbing angle for a ground ladder?

75 degrees.

How do you calculate the correct distance to place the butt of a ladder from a building?

Divide the working length of the ladder by 4 (e.g., if the ladder touches at 20 feet up, the base must be 5 feet away).

For window rescue, where should the tip of the ladder be placed?

Right at or just below the windowsill.

For roof access, how many rungs must extend above the roofline?

A minimum of 3 to 5 rungs.

What is the weight capacity rating for standard fire service ground ladders?

750 pounds (rated for a three-person load including equipment).

How many firefighters are typically required to safely carry a 35-foot extension ladder?

Three to four firefighters.

What is a roof ladder, and how is it secured?

A straight ladder equipped with folding hooks at the tip that hook securely over the roof ridge.