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Korea Fire Facility Manager (소방시설관리사) study materials
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Korea Fire Facility Manager (소방시설관리사) practice questions

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Question 1Combustion, heat transfer and smoke behavior

Which element differentiates the Fire Tetrahedron (연소의 4요소) from the classical Fire Triangle (연소의 3요소), providing the theoretical foundation for chemical flame inhibition by dry chemical and gaseous clean extinguishing agents?

  1. Vaporized combustible fuel (가연물)
  2. Thermal ignition energy (점화원)
  3. Atmospheric oxygen oxidizer (산소공급원)
  4. Uninhibited chemical chain reaction (연쇄반응) Correct answer.

Explanation

The Fire Tetrahedron adds the uninhibited chemical chain reaction (연쇄반응) to fuel, oxidizer, and heat. Halogenated clean agents and dry chemical powders extinguish flames primarily by scavenging free radicals (H· and OH·), thereby breaking this chain reaction (부촉매 소화 / 화학적 억제소화).

Question 2Combustion, heat transfer and smoke behavior

Under South Korean national fire protection standards, which fire classification and identification color correctly correspond to electrical equipment fires (전기화재)?

  1. Class A (일반화재) - White (백색)
  2. Class B (유류화재) - Yellow (황색)
  3. Class C (전기화재) - Blue (청색) Correct answer.
  4. Class K (주방화재) - Black (흑색)

Explanation

In South Korea, fires are classified into Class A (Ordinary combustibles, White mark), Class B (Flammable liquids and gases, Yellow mark), Class C (Electrical equipment fires, Blue mark), and Class K (Commercial cooking kitchen fires, typically uncolored or purple). Electrical fires are designated as Class C with a blue circular marking.

Question 3Combustion, heat transfer and smoke behavior

A storage compartment with a floor area of 100 m² contains 2,000 kg of wood pallets (calorific value 4,500 kcal/kg) and 500 kg of plastic polymers (calorific value 9,000 kcal/kg). Given that the standard reference calorific value of wood (H₀) is 4,500 kcal/kg, what is the calculated Fire Load (화재하중, kg/m²) under compartment fire dynamics principles?

  1. 15 kg/m²
  2. 25 kg/m²
  3. 30 kg/m² Correct answer.
  4. 45 kg/m²

Explanation

Fire Load Q = Σ(M_i × H_i) / (A × H₀). Total heat release = (2,000 kg × 4,500 kcal/kg) + (500 kg × 9,000 kcal/kg) = 9,000,000 + 4,500,000 = 13,500,000 kcal. Equivalent wood mass = 13,500,000 / 4,500 = 3,000 kg. Dividing by floor area A = 100 m² yields Q = 3,000 / 100 = 30 kg/m².

Question 4Combustion, heat transfer and smoke behavior

In compartment fire dynamics, which phenomenon defines Flashover (플래시오버)?

  1. The violent deflagration resulting from fresh air suddenly entering an oxygen-depleted compartment containing accumulated pyrolysis gases
  2. The supersonic shockwave generated by flammable gas mixture detonation in an unventilated corridor
  3. The sudden downward boilover of an open-top liquid storage tank during extinguishment operations
  4. The rapid transition from a localized fuel-bed fire to full room surface involvement driven by radiative feedback from the hot ceiling smoke layer Correct answer.

Explanation

Flashover is the rapid transition from a localized growth-stage fire to a fully developed fire where all combustible surfaces in the compartment ignite nearly simultaneously, driven by radiant heat flux (~20 kW/m²) from the hot smoke layer (~500–600 °C).

Question 5Combustion, heat transfer and smoke behavior

Firefighters arriving at a tightly sealed commercial building observe yellowish-gray puffing smoke pulsing through window seals, blackened glass vibrating under internal suction, and extreme localized heat with no visible interior flames. Which hazardous phenomenon do these warning signs indicate?

  1. Flashover (플래시오버)
  2. Backdraft (백드래프트) Correct answer.
  3. BLEVE (비등액체증기폭발)
  4. Slopover (슬롭오버)

Explanation

Yellowish-gray pulsing/puffing smoke, inward air suction at cracks, stained or vibrating window panes, and lack of visible flame in an airtight enclosure indicate an oxygen-starved, fuel-rich fire undergoing incomplete combustion, which triggers a Backdraft (백드래프트) when fresh air enters.

Question 6Combustion, heat transfer and smoke behavior

What is the fundamental scientific difference in driving mechanism between Flashover (플래시오버) and Backdraft (백드래프트)?

  1. Flashover generates supersonic shockwaves exceeding 1,000 m/s, whereas Backdraft is a slow smoldering reaction
  2. Flashover occurs exclusively in hydrocarbon liquids, whereas Backdraft occurs exclusively in cellulosic solid materials
  3. Flashover requires negative compartment gauge pressure, whereas Backdraft occurs only under positive mechanical pressurization
  4. Flashover is driven by thermal radiation feedback during the growth stage, whereas Backdraft is an explosive deflagration driven by sudden oxygen introduction into an under-ventilated compartment Correct answer.

Explanation

Flashover is a thermal transition occurring when radiative heat flux from the upper smoke layer ignites all exposed fuel surfaces simultaneously (usually fuel-controlled or pre-ventilation limit). Backdraft is a ventilation-induced deflagration occurring when fresh air mixes with hot unburned pyrolysis products in an oxygen-depleted (ventilation-controlled) enclosure.

Question 7Combustion, heat transfer and smoke behavior

In high-rise building smoke dynamics during winter conditions (indoor temperature T_i > outdoor temperature T_o), which statement accurately describes the Stack Effect (굴뚝효과 / 연돌효과) and pressure distribution?

  1. Indoor pressure is lower than outdoor pressure on upper floors, causing cold outside air to infiltrate at the roof
  2. Indoor pressure is higher than outdoor pressure above the Neutral Pressure Plane, driving smoke outward through upper floors and vertical shafts Correct answer.
  3. Air flows downward inside vertical shafts because warm air cools as it moves toward the roof
  4. The theoretical stack effect pressure difference is inversely proportional to building vertical height

Explanation

Under normal winter stack effect (T_i > T_o), warm air inside vertical shafts rises by buoyancy. Below the Neutral Pressure Plane (NPP), indoor pressure is lower than outside, drawing cold air inward. Above the NPP, indoor pressure exceeds outside atmospheric pressure, driving smoke and gases outward from shafts into upper floors. Korean terminology: 중성대.

Question 8Combustion, heat transfer and smoke behavior

What is the definition and physical significance of the Neutral Pressure Plane (중성대, NPP) across a vertical building boundary or compartment opening?

  1. The flame base level where fuel vaporization equals air entrainment
  2. The ceiling layer elevation where smoke temperature drops below 100 °C
  3. The boundary where oxygen concentration reaches 21% by volume
  4. The horizontal boundary elevation where indoor hydrostatic pressure exactly equals outdoor atmospheric pressure (ΔP = 0) Correct answer.

Explanation

The Neutral Pressure Plane (중성대) is the horizontal plane where the pressure difference between the interior of the compartment/building and the outside atmosphere is zero (ΔP = 0). Below the NPP, flow moves from higher to lower pressure (inward in winter); above the NPP, flow moves outward.

Question 9Combustion, heat transfer and smoke behavior

In performance-based life safety egress design (성능위주설계), a compartment's Available Safe Egress Time (ASET) is determined by CFD modeling to be 300 seconds. The egress evacuation timeline calculation establishes: detector activation time t_det = 25 s, alarm broadcasting delay t_alarm = 25 s, occupant pre-movement time t_pre = 60 s, and travel egress time t_travel = 120 s. What is the Required Safe Egress Time (RSET) and the resulting evacuation Safety Margin (여유시간)?

  1. RSET = 205 s, Safety Margin = 95 s
  2. RSET = 230 s, Safety Margin = 70 s Correct answer.
  3. RSET = 255 s, Safety Margin = 45 s
  4. RSET = 300 s, Safety Margin = 0 s

Explanation

RSET = t_det + t_alarm + t_pre + t_travel = 25 + 25 + 60 + 120 = 230 seconds. The Safety Margin = ASET - RSET = 300 - 230 = 70 seconds. Because ASET > RSET, life safety tenability is maintained.

Question 10Combustion, heat transfer and smoke behavior

A fuel gas mixture consists of 60% Methane (CH₄, lower flammable limit LFL = 5.0 vol%) and 40% Propane (C₃H₈, LFL = 2.1 vol%) by volume. Using Le Chatelier's Law (르샤틀리에 법칙), what is the calculated Lower Flammable Limit (L_mix) of this mixture in air?

  1. 2.85 vol%
  2. 3.22 vol% Correct answer.
  3. 3.55 vol%
  4. 4.10 vol%

Explanation

Le Chatelier's formula: 100 / L_mix = Σ(V_i / LFL_i) = (60 / 5.0) + (40 / 2.1) = 12 + 19.0476 = 31.0476. Therefore, L_mix = 100 / 31.0476 ≈ 3.22 vol%.

Question 11Combustion, heat transfer and smoke behavior

Which action or condition will INCREASE the Minimum Ignition Energy (MIE, 최소발화에너지) of a combustible vapor-air mixture, thereby reducing its ignition sensitivity?

  1. Preheating the gas mixture to an elevated initial temperature
  2. Increasing the initial pressure of the mixture
  3. Enriching the oxidizer with pure oxygen above 21%
  4. Introducing an inert gas such as Nitrogen (N₂) or Carbon Dioxide (CO₂) Correct answer.

Explanation

Introducing inert gases (N₂, CO₂, Ar) dilutes reactant concentrations, absorbs thermal energy through their heat capacity, and lowers radical collision rates, which increases the Minimum Ignition Energy (MIE) required to establish self-sustaining flame propagation.

Question 12Combustion, heat transfer and smoke behavior

Which operating condition produces the HIGHEST theoretical adiabatic flame temperature (이론단열화염온도) during hydrocarbon combustion?

  1. Combustion with 100% excess air (equivalence ratio Φ = 0.5)
  2. Combustion at stoichiometric ratio in pure Oxygen (O₂) with preheated reactants Correct answer.
  3. Combustion at atmospheric pressure with 80% relative humidity
  4. Combustion in air under intense radiative cooling and high CO dissociation

Explanation

Theoretical adiabatic flame temperature reaches its absolute maximum when combustion occurs at stoichiometric proportions in pure oxygen (eliminating the substantial thermal heat sink of atmospheric nitrogen) with reactants preheated prior to ignition.

Question 13Combustion, heat transfer and smoke behavior

According to the Stefan-Boltzmann law (E = ε·σ·T⁴), thermal radiation from a hot smoke layer increases with the fourth power of absolute temperature (K). If the absolute temperature of a ceiling smoke layer doubles from 400 K to 800 K, by what factor does its radiant emissive power increase?

  1. 2 times
  2. 4 times
  3. 8 times
  4. 16 times Correct answer.

Explanation

Radiant emissive power is proportional to T⁴. When T increases by a factor of 2 (800 / 400 = 2), emissive power increases by 2⁴ = 16 times. This extreme non-linear growth explains why radiative heat flux accelerates compartment fire growth toward flashover.

Question 14Combustion, heat transfer and smoke behavior

Which sequence correctly details the physical chain of events that triggers a BLEVE (Boiling Liquid Expanding Vapor Explosion, 비등액체증기폭발) in an LPG storage container?

  1. Subsurface water layer is heated to boiling point → steam piston lifts burning fuel out of tank → slopover deflagration occurs
  2. Combustible gas in the vapor space reaches detonation velocity → inward implosion of vessel walls
  3. Static electricity ignites vent emissions → steady relief flare combustion without tank wall failure
  4. External fire impinges on the tank vapor space → wall temperature rises and steel strength drops rapidly → container shell ruptures catastrophically → superheated liquid boils instantaneously → massive vapor fireball expands Correct answer.

Explanation

A BLEVE occurs when an external fire heats the vapor space of a pressurized liquid tank. Because vapor cannot cool the metal as effectively as liquid, the unwetted shell steel loses structural tensile strength, ruptures under pressure, causing instantaneous flash vaporization of superheated liquid and an expanding fireball.

Question 15Combustion, heat transfer and smoke behavior

In buoyant diffusion flame dynamics, McCaffrey correlated vertical plume properties into three distinct aerodynamic zones based on the height-to-heat release parameter z / Q^(2/5). What are these three zones from the fuel surface upward?

  1. Primary reaction zone → Neutral interface zone → Quenching zone
  2. Smoldering region → Pyrolysis region → Radiation flash region
  3. Laminar boundary zone → Sonic transition zone → Dissipation zone
  4. Continuous flame region → Intermittent flame region → Buoyant plume region Correct answer.

Explanation

McCaffrey's buoyant plume model defines three vertical zones: 1. Continuous flame region (연속화염영역, z/Q^(2/5) < 0.08) where gas accelerates and temperature is constant; 2. Intermittent flame region (간헐화염영역, 0.08 ≤ z/Q^(2/5) < 0.20) with fluctuating flame tips; and 3. Buoyant plume region (부력플룸영역, z/Q^(2/5) ≥ 0.20) where temperature and velocity decay due to air entrainment.

Question 16Mechanical and electrical protection-system principles

Under Bernoulli's Theorem for steady, frictionless, incompressible fluid flow along a streamline, which term represents the total head (전수두, H)?

  1. H = z + (P / ρ) + (v / 2g)
  2. H = (z / g) + P + v²
  3. H = γ·z + P·v + (g / 2)
  4. H = z + (P / γ) + (v² / 2g) Correct answer.

Explanation

Bernoulli's equation states that total mechanical energy per unit weight is constant along a streamline: H = z (elevation head, 위치수두) + P/γ (pressure head, 압력수두) + v²/(2g) (velocity head, 속도수두), where γ is specific weight and g is gravitational acceleration.

Question 17Mechanical and electrical protection-system principles

In fire piping hydraulics, the Hazen-Williams formula expresses friction head loss as h_f = 6.05 × 10⁴ × L × Q^1.85 / (C^1.85 × d^4.87). If the internal diameter (d) of a supply pipe is doubled (2d) while maintaining the same length, roughness coefficient C, and flow rate Q, by approximately what factor is the friction loss reduced?

  1. Reduced to approximately 1/2 (~50.0%)
  2. Reduced to approximately 1/4 (~25.0%)
  3. Reduced to approximately 1/16 (~6.25%)
  4. Reduced to approximately 1/29.2 (~3.42%) Correct answer.

Explanation

In Hazen-Williams, h_f is inversely proportional to d^4.87. Doubling the diameter scales friction loss by (1/2)^4.87 = 1 / (2^4.87) ≈ 1 / 29.25 ≈ 0.0342 (3.42%). Thus friction loss decreases drastically by about 29.2 times.

Question 18Mechanical and electrical protection-system principles

A laminar water flow (Re = 1,000) passes through a straight horizontal pipe of length L = 20 m and internal diameter D = 0.05 m at mean velocity v = 1.0 m/s. Given g = 9.8 m/s² and the Darcy friction factor for laminar flow f = 64 / Re, what is the friction head loss (h_f) calculated via the Darcy-Weisbach equation?

  1. 0.65 m
  2. 1.31 m Correct answer.
  3. 2.61 m
  4. 5.22 m

Explanation

Laminar friction factor f = 64 / 1,000 = 0.064. Applying Darcy-Weisbach: h_f = f × (L / D) × (v² / 2g) = 0.064 × (20 / 0.05) × (1.0² / (2 × 9.8)) = 0.064 × 400 × (1 / 19.6) = 25.6 / 19.6 ≈ 1.306 m ≈ 1.31 m.

Question 19Mechanical and electrical protection-system principles

The standard nozzle discharge formula for fire hose streams is q = 2.065·c·d²·√P (where q is flow in L/min, d is nozzle diameter in mm, P is discharge pressure in MPa, and c is nozzle discharge coefficient). For an indoor fire hydrant nozzle with diameter d = 13 mm, discharge coefficient c = 0.97, and operating nozzle pressure P = 0.25 MPa, what is the calculated water discharge rate (q)?

  1. 118.5 L/min
  2. 145.2 L/min
  3. 169.3 L/min Correct answer.
  4. 195.0 L/min

Explanation

q = 2.065 × c × d² × √P = 2.065 × 0.97 × (13)² × √0.25 = 2.003 × 169 × 0.5 ≈ 169.26 L/min ≈ 169.3 L/min.

Question 20Mechanical and electrical protection-system principles

Which operational scenario and hydraulic phenomenon describes Water Hammer (수격작용) in firefighting pump discharge piping, and which device effectively mitigates it?

  1. Excessive pump motor speed causes mechanical shaft oscillation; mitigated by installing dynamic vibration isolators
  2. Pump impeller suction pressure drops below water vapor pressure creating collapsing bubbles; mitigated by increasing pump suction lift
  3. Air pockets form at high piping peaks reducing discharge flow; mitigated by installing air vents only
  4. Sudden valve closure or pump trip causes rapid kinetic energy conversion into extreme acoustic pressure surges; mitigated by installing water hammer arresters or slow-closing check valves Correct answer.

Explanation

Water hammer occurs when fluid velocity changes abruptly (e.g. quick valve shutoff or pump power cutoff), converting kinetic energy into severe acoustic pressure waves (ΔP = ρ·a·Δv by Joukowsky's equation). It is mitigated by water hammer arresters, surge tanks, flywheel pumps, or slow-closing non-slam check valves. Korean terminology: 수격방지기.

Question 21Mechanical and electrical protection-system principles

A fire pump is designed to discharge Q = 1,200 L/min (0.02 m³/s) at total head H = 70 m. Given water density ρ = 1,000 kg/m³, pump efficiency η = 0.65, and motor power margin factor (전달계수) k = 0.15 (15%), what is the required motor output rating in kilowatts (kW)?

  1. 15.8 kW
  2. 21.1 kW
  3. 24.3 kW Correct answer.
  4. 32.5 kW

Explanation

Motor output P = [γ·Q·H / (102·η)] × (1 + k). Here, γ = 1,000 kg/m³, Q = 0.02 m³/s, H = 70 m, η = 0.65, and (1 + k) = 1.15. Hydraulic water power = 1000 × 0.02 × 70 / 102 = 13.725 kW. Shaft power = 13.725 / 0.65 = 21.115 kW. Applying transmission margin 1.15 yields P = 21.115 × 1.15 ≈ 24.28 kW ≈ 24.3 kW.

Question 22Mechanical and electrical protection-system principles

Which design condition must be satisfied to prevent Cavitation (공동현상) during fire pump operation?

  1. Required Net Positive Suction Head (NPSHr) must exceed atmospheric pressure head
  2. Pump suction velocity must exceed 5.0 m/s to sweep vapor bubbles away
  3. Suction piping diameter must be smaller than pump suction inlet flange diameter
  4. Available Net Positive Suction Head (NPSHa) must exceed Required Net Positive Suction Head (NPSHr), ideally NPSHa ≥ NPSHr × 1.15 Correct answer.

Explanation

Cavitation occurs when absolute pressure at the pump suction falls below water vapor pressure. To prevent cavitation, NPSHa (determined by system atmospheric pressure, suction lift, and friction) must exceed NPSHr (manufacturer's impeller requirement) with a safety margin (NPSHa ≥ 1.15–1.30 × NPSHr).

Question 23Mechanical and electrical protection-system principles

Under South Korean technical standards for foam extinguishing systems (포소화설비), which expansion ratio range classifies Low-Expansion Foam (저발포) compared to High-Expansion Foam (고발포)?

  1. Low expansion: expansion ratio 5 or less; High expansion: expansion ratio 50 to 100
  2. Low expansion: expansion ratio 20 to 100; High expansion: expansion ratio over 2,000
  3. Low expansion: expansion ratio 20 or less; High expansion: expansion ratio 80 or more and under 1,000 Correct answer.
  4. Low expansion: expansion ratio 100 to 500; High expansion: expansion ratio 500 to 800

Explanation

Korean foam agent standards classify foam by expansion ratio (팽창비): low-expansion foam (저발포) has an expansion ratio of 20 or less and is discharged through foam heads and compressed-air foam heads; high-expansion foam (고발포) has an expansion ratio of 80 or more and under 1,000 and is discharged through high-expansion fixed foam outlets. High-expansion foam is further graded as Type 1 (80 to under 250), Type 2 (250 to under 500) and Type 3 (500 to under 1,000). The band between 20 and 80 is not a classified category under the Korean standard.

Question 24Mechanical and electrical protection-system principles

In firefighting foam agent performance evaluation, what is the definition and operational significance of 25% Drainage Time (25% 배액시간)?

  1. The time required for 25% of the fuel pool surface to be covered by foam solution
  2. The time required for foam depth to reduce by 25% due to wind evaporation
  3. The time required for 25% of the total liquid solution volume contained in the expanded foam sample to drain out; indicates foam stability and water retention under heat Correct answer.
  4. The time required to discharge 25% of the foam concentrate tank through the proportioner

Explanation

The 25% drainage time is the time required for one-fourth (25%) of the liquid volume in the generated foam to separate and drain out. Longer drainage times reflect higher foam bubble stability, heat resistance, and fuel vapor suppression duration.

Question 25Mechanical and electrical protection-system principles

Which dry chemical extinguishing agent is designated for multi-purpose Class A, B, and C fires, and what unique chemical mechanism enables it to extinguish deep-seated Class A cellulose embers?

  1. Potassium bicarbonate (KHCO₃, 자색) forms a conductive ash layer
  2. Sodium bicarbonate (NaHCO₃, 백색) decomposes to release water vapor only
  3. Monoammonium phosphate (NH₄H₂PO₄, 담홍색) decomposes under heat to form Metaphosphoric acid (HPO₃), which glazes solid fuel surfaces and prevents re-ignition Correct answer.
  4. Potassium bicarbonate with urea (회색) forms a foaming surfactant blanket on wood

Explanation

Type 3 dry chemical (ABC multi-purpose, dyed pink/담홍색) uses monoammonium phosphate (NH₄H₂PO₄). Upon thermal decomposition above 190 °C, it releases metaphosphoric acid (HPO₃) and polymetaphosphoric acid, which forms an impermeable glassy coating over glowing embers, cutting off oxygen and preventing re-ignition.

Question 26Mechanical and electrical protection-system principles

What is the primary physical and chemical extinguishing distinction between Halocarbon clean agents (e.g., HFC-227ea, FK-5-1-12) and Inert Gas clean agents (e.g., IG-100, IG-541)?

  1. Halocarbons extinguish exclusively by starving the flame of oxygen and must discharge within 1 minute, whereas inert gases extinguish by cooling the fuel surface cryogenically and are allowed 10 seconds
  2. Halocarbons are electrically conductive and are therefore barred from energised electrical rooms, whereas inert gases are non-conductive and are the only clean agents permitted in such spaces
  3. Halocarbons extinguish mainly by absorbing heat in the flame zone with some chemical radical scavenging and must discharge within 10 seconds, whereas inert gases extinguish purely by diluting oxygen to roughly 12 to 14% and are allowed 1 minute for Class B fires and 2 minutes for Class A and C fires Correct answer.
  4. Halocarbons leave a heavy powder residue that must be vacuumed from equipment after discharge, whereas inert gases evaporate instantly and leave the protected space entirely clean

Explanation

Halocarbon agents (할로겐화합물 소화약제) work chiefly by absorbing heat in the flame zone, with a secondary chemical inhibition effect, and NFTC 107A requires 95% of the minimum design concentration to be delivered within 10 seconds so that the flame is knocked down before significant hydrogen fluoride forms. Inert gas agents (불활성기체 소화약제) work purely by physical oxygen dilution to about 12 to 14% and are given 1 minute for Class B fires and 2 minutes for Class A and C fires, which also limits enclosure overpressure.

Question 27Mechanical and electrical protection-system principles

Regarding the thermodynamic state properties of Carbon Dioxide (CO₂) extinguishing agents, what are the exact Triple Point (삼중점) and Critical Point (임계점) conditions?

  1. Triple Point: -78.5 °C at 0.101 MPa (1.0 atm); Critical Point: 50.0 °C at 15.0 MPa
  2. Triple Point: 0.0 °C at 0.101 MPa (1.0 atm); Critical Point: 100.0 °C at 22.1 MPa
  3. Triple Point: -56.6 °C at 0.518 MPa (5.11 atm); Critical Point: 31.35 °C at 7.38 MPa (72.8 atm) Correct answer.
  4. Triple Point: -18.0 °C at 2.1 MPa; Critical Point: 21.0 °C at 5.7 MPa

Explanation

Carbon dioxide has its triple point where solid, liquid, and gas coexist at -56.6 °C and 0.518 MPa. Its critical point, above which liquid and vapor phases merge into a supercritical fluid, is 31.35 °C at 7.38 MPa. At standard atmospheric pressure (0.1 MPa), liquid CO₂ cannot exist, sublimating directly between solid (-78.5 °C) and gas.

Question 28Mechanical and electrical protection-system principles

A diesel emergency generator room with a volume of V = 200 m³ is protected by a high-pressure CO₂ total flooding system (전역방출방식) designed for a surface fire. Under NFTC 106 the design agent factor for a protected volume of 150 m³ or more and under 1,450 m³ is 0.8 kg/m³, and all openings close automatically (A = 0 m²). Using 45 kg CO₂ cylinders, what is the minimum number of cylinders required?

  1. 2 cylinders
  2. 4 cylinders Correct answer.
  3. 6 cylinders
  4. 8 cylinders

Explanation

Agent quantity W = V × m + A × a = (200 m³ × 0.8 kg/m³) + 0 = 160 kg, which also clears the 135 kg minimum that NFTC 106 sets for this volume band. Number of cylinders = 160 kg / 45 kg = 3.56, and because a partial cylinder cannot be installed this rounds up to 4 cylinders. The surface-fire factors step down with volume: under 45 m³ 1.00 kg/m³, 45 to under 150 m³ 0.90, 150 to under 1,450 m³ 0.80, and 1,450 m³ or more 0.75.

Question 29Mechanical and electrical protection-system principles

A DC 24V fire alarm Notification Appliance Circuit (NAC) draws a continuous signaling current of I = 0.50 A through a copper conductor loop with total wire resistance R = 4.0 Ω. What is the line voltage drop (ΔV) and total thermal power dissipated in the wiring (P)?

  1. ΔV = 2.0 V, P = 1.0 W Correct answer.
  2. ΔV = 1.0 V, P = 0.5 W
  3. ΔV = 4.0 V, P = 2.0 W
  4. ΔV = 8.0 V, P = 4.0 W

Explanation

Applying Ohm's Law: ΔV = I × R = 0.50 A × 4.0 Ω = 2.0 V. Power dissipation: P = I² × R = (0.50)² × 4.0 = 0.25 × 4.0 = 1.0 W (or P = ΔV × I = 2.0 V × 0.50 A = 1.0 W).

Question 30Mechanical and electrical protection-system principles

Under National Fire Safety Technical Code NFTC 203 for automatic fire alarm systems, what is the maximum allowable line voltage drop between the fire alarm receiver (수신기) and the most remote detector or notification appliance operating on rated DC 24V?

  1. Not exceeding 5% (terminal voltage ≥ 22.8 V)
  2. Not exceeding 10% (terminal voltage ≥ 21.6 V)
  3. Not exceeding 20% (terminal voltage ≥ 19.2 V) Correct answer.
  4. Not exceeding 30% (terminal voltage ≥ 16.8 V)

Explanation

Under NFTC 203, fire detection and notification circuits powered by DC 24V must be sized so that line voltage drop does not exceed 20% of rated voltage. Consequently, the minimum operating voltage at the most remote end of the circuit must remain at or above 19.2 V (24 V × 0.80).

Question 31Mechanical and electrical protection-system principles

The emergency power supply battery capacity for a fire alarm control unit is calculated using C = (1 / L) × Σ(K_i × I_i). The system requires a supervisory monitoring standby current I₁ = 0.20 A for 60 minutes (capacity conversion coefficient K₁ = 1.2 h), followed by simultaneous alarm signaling current I₂ = 1.0 A for 10 minutes (capacity conversion coefficient K₂ = 0.4 h). Given battery maintenance aging factor L = 0.80, what is the required battery capacity (C)?

  1. 0.50 Ah
  2. 0.64 Ah
  3. 0.80 Ah Correct answer.
  4. 1.20 Ah

Explanation

Applying the formula: C = (1 / L) × (K₁·I₁ + K₂·I₂) = (1 / 0.80) × (1.2 × 0.20 + 0.4 × 1.0) = 1.25 × (0.24 + 0.40) = 1.25 × 0.64 = 0.80 Ah.

Question 32Mechanical and electrical protection-system principles

In conventional P-type fire alarm initiation circuits (감지기 회로), why is an End-of-Line Resistor (종단저항) installed at the furthest end of the circuit loop rather than inside the receiver cabinet?

  1. To allow the receiver to continuously supervise circuit wiring integrity by passing a minute supervisory current through the entire wire run Correct answer.
  2. To boost the operating voltage for the furthest smoke detector
  3. To provide ground fault surge suppression during lightning strikes
  4. To convert analog sensor pulses into digital multiplex signals

Explanation

An End-of-Line (EOL) resistor (typically 10 kΩ) placed at the loop terminus allows a continuous, small supervisory current (~mA) to circulate through the complete wiring loop. If the wire breaks anywhere along the line, current drops to zero, triggering an immediate wiring fault / open circuit trouble signal (단선경보) at the receiver.

Question 33Mechanical and electrical protection-system principles

When starting high-capacity three-phase induction motors for fire pumps, what is the primary technical effect of using a Star-Delta (Y-Δ) reduced voltage starter compared to Direct-On-Line (DOL) starting?

  1. Starting voltage across windings is reduced to 1/√3 (~58%), reducing starting current and starting torque to 1/3 (approx. 33.3%) of DOL values Correct answer.
  2. Starting current increases by 3 times to accelerate the pump faster
  3. Starting torque is doubled to overcome high pipe friction
  4. Motor operating frequency is modulated continuously from 0 to 60 Hz

Explanation

In Star (Y) connection, phase voltage is V_L / √3 (57.7% of line voltage). Because current is proportional to voltage and torque is proportional to voltage squared, both starting line current and starting torque in Star configuration are reduced to exactly 1/3 (33.3%) of the values observed during Direct-On-Line Delta starting.

Question 34Mechanical and electrical protection-system principles

Under the fire safety technical code for high-rise buildings (고층건축물의 화재안전기술기준, NFTC 604), for how long must the emergency power supply be able to operate the indoor fire hydrant and sprinkler systems in a building of 30 to 49 storeys, and in a building of 50 storeys or more?

  1. 20 minutes for 30 to 49 storeys; 30 minutes for 50 storeys or more
  2. 40 minutes for 30 to 49 storeys; 60 minutes for 50 storeys or more Correct answer.
  3. 60 minutes for 30 to 49 storeys; 120 minutes for 50 storeys or more
  4. 10 minutes for 30 to 49 storeys; 20 minutes for 50 storeys or more

Explanation

NFTC 604 applies to buildings of 30 storeys or more or 120 m or higher. It requires the emergency power supply - a standby generator or a storage battery installation - to run the indoor fire hydrant system and the sprinkler system for at least 40 minutes, extended to at least 60 minutes in buildings of 50 storeys or more. The same 40 and 60 minute durations apply to the smoke control system and the connecting standpipe system. For ordinary buildings outside the high-rise code the baseline emergency power duration is 20 minutes.

Question 35Mechanical and electrical protection-system principles

Which statement correctly distinguishes the operating principles of Wet-Pipe (습식), Dry-Pipe (건식), Preaction (준비작동식), and Deluge (일제살수식) automatic sprinkler systems?

  1. Wet-pipe has water throughout; Dry-pipe uses pressurized air holding a clapper closed; Preaction requires fire detector activation to flood dry piping before heads fuse; Deluge uses open heads and floods the entire zone simultaneously upon valve actuation Correct answer.
  2. Wet-pipe uses foam concentrate; Dry-pipe discharges nitrogen gas only; Preaction uses open heads; Deluge uses glass bulb heads
  3. Wet-pipe requires electrical smoke detector interlocks; Dry-pipe is pressurized with water; Preaction discharges immediately upon freezing
  4. All four systems use open nozzles that discharge simultaneously upon manual pull station activation

Explanation

In Wet systems, piping contains water under pressure, discharging immediately when a heat-sensitive bulb bursts. In Dry systems, piping contains pressurized air/nitrogen holding a clapper shut; air vents first when a head opens. In Preaction systems, piping contains atmospheric air, and an electrical fire detection signal trips the valve to pre-fill pipes with water before heads burst. In Deluge systems, open heads are installed, discharging water across the entire zone when the deluge valve trips.

Question 36Mechanical and electrical protection-system principles

In a Preaction Sprinkler System (준비작동식 유수검지장치), why is a Cross-Zone Detection Circuit (교차회로방식) employed to actuate the deluge/preaction valve solenoid?

  1. To prevent accidental system actuation and water damage from a single detector false alarm by requiring two separate detector circuits (Circuit A and Circuit B) to actuate simultaneously Correct answer.
  2. To double the operating voltage supplied to each detector
  3. To allow the system to operate when utility AC power is completely lost
  4. To automatically modulate the water flow rate depending on flame color

Explanation

Cross-zone detection (교차회로방식) arranges detectors such that adjacent detectors belong to two separate circuit loops (Loop A and Loop B). The preaction valve solenoid trips only when at least one detector in Loop A AND one detector in Loop B activate simultaneously. This prevents water from prematurely flooding the piping network due to a transient false alarm on a single detector.

Question 37Mechanical and electrical protection-system principles

In gaseous total flooding fire extinguishing systems, residual oxygen concentration is related to agent design volumetric concentration (C, %) by the formula O₂% = 21 × (1 - C / 100). For a total flooding CO₂ system designed to achieve a 34% design concentration (standard for electrical equipment rooms), what is the calculated residual oxygen concentration?

  1. 9.50%
  2. 11.25%
  3. 12.60%
  4. 13.86% Correct answer.

Explanation

Applying the oxygen dilution formula: O₂% = 21 × (1 - C / 100) = 21 × (1 - 0.34) = 21 × 0.66 = 13.86%. Because flame propagation for most hydrocarbons ceases when oxygen drops below 14–15%, this 13.86% residual oxygen reliably extinguishes the fire.

Question 38Mechanical and electrical protection-system principles

In automatic fire alarm initiation technology, what is the fundamental operating distinction between a Rate-of-Rise Spot Thermal Detector (차동식스포트형 감지기) and a Fixed-Temperature Spot Thermal Detector (정온식스포트형 감지기)?

  1. Rate-of-Rise detectors sense smoke obscuration, while Fixed-Temperature detectors sense flame radiation
  2. Rate-of-Rise detectors actuate when the rate of ambient temperature increase exceeds a preset limit using a flexible diaphragm and calibrated air leak orifice, whereas Fixed-Temperature detectors actuate when ambient temperature reaches a specific fixed threshold Correct answer.
  3. Rate-of-Rise detectors use radioactive americium-241 sources, whereas Fixed-Temperature detectors use infrared cameras
  4. Rate-of-Rise detectors are prohibited in boiler rooms, whereas Fixed-Temperature detectors are prohibited in kitchens

Explanation

A Rate-of-Rise (차동식) spot detector contains an internal air chamber sealed with a flexible metallic diaphragm and a calibrated leak orifice (리크구멍). Slow ambient heating allows air to escape through the orifice without triggering an alarm. Rapid temperature rise expands air faster than it can escape, flexing the diaphragm to close electrical contacts. Fixed-temperature (정온식) detectors use a bimetallic strip or fusible alloy that triggers only when temperature reaches a fixed setting (e.g. 70 °C).

Question 39Mechanical and electrical protection-system principles

What is the primary architectural and signaling difference between a conventional P-Type Fire Alarm Receiver (P형 수신기) and an addressable R-Type Fire Alarm Receiver (R형 수신기)?

  1. P-type uses dedicated hardwired conductor pairs for each individual detection zone connected directly to analog relay lamps, whereas R-type uses digital multiplex data communication across a shared communication bus connecting to addressable transponders Correct answer.
  2. P-type is digital and microprocessor-based, whereas R-type uses mechanical steam whistles
  3. P-type supports up to 10,000 addressable points, whereas R-type is limited to 5 zones
  4. P-type requires fiber optic cabling, whereas R-type requires bare uninsulated copper wires

Explanation

P-type (Proprietary/Panel) receivers use individual dedicated copper wires for every detection zone (common line, zone line, bell line, phone line), resulting in massive wire bundles as building size grows. R-type (Record/Remote multiplex) receivers transmit digital signals over a 2- or 4-wire multiplex data communication loop connecting addressable transponders and detectors, recording events with precise time and address logs on an LCD panel. Korean terminology: 중계기.

Question 40Mechanical and electrical protection-system principles

Under the wiring installation standards annexed to the National Fire Safety Technical Codes, what distinguishes Fire-Resistant Wiring (내화배선) from Heat-Resistant Wiring (내열배선), and where must fire-resistant wiring be used?

  1. Both classes are the same cable, verified by immersion in boiling water for one hour, and both are used only for decorative landscape lighting and external signage circuits
  2. Fire-resistant wiring is restricted to telephone and intercom lines, while heat-resistant wiring is used for the main utility transformer feeders serving the whole building
  3. Fire-resistant wiring is rated for 100 °C for one hour and heat-resistant wiring for 50 °C for five minutes, and both are permitted only on exit sign and emergency lighting circuits
  4. Fire-resistant wiring must keep the circuit energised while exposed to fire, verified by the KS C IEC 60331 circuit integrity test or installed in the prescribed protective conduit buried in the finish, and is required for the power feeders of fire pumps, pressurisation fans and smoke exhaust fans; heat-resistant wiring need only resist heat, verified by the KS C IEC 60332 flame-propagation standard, and is permitted for detection and control signalling circuits Correct answer.

Explanation

The wiring annex to the fire safety technical codes distinguishes the two by the performance the cable must keep under fire exposure and by the installation method. Fire-resistant wiring (내화배선) has to keep the circuit energised during a fire: it is either a certified fire-resistant cable meeting the circuit integrity standard KS C IEC 60331 (with flame propagation to KS C IEC 60332-3-24), or an ordinary heat-resistant cable installed in metal conduit buried at least 25 mm inside a fire-resistant structural finish. It is required for the power feeders of the life-safety motors - fire pumps, stairwell pressurisation fans and smoke exhaust fans. Heat-resistant wiring (내열배선) need only withstand heat and may be run in exposed metal conduit or trunking, and is permitted for detection, control and notification signalling circuits.

Question 41Korean fire legislation and administrative principles

Under the Framework Act on Fire Services (소방기본법 제23조), who holds the statutory authority to establish a Fire Operations Zone (소방활동구역) at an incident scene, and who may enter the restricted perimeter?

  1. The Fire Commander (소방대장); entry is restricted to firefighting personnel, victims/residents, medical responders, public utility repair crews, and accredited news journalists Correct answer.
  2. The Provincial Governor (시·도지사); entry is permitted only to licensed fire facility managers
  3. The Police Station Chief (경찰서장); entry is permitted to all building owners without limitation
  4. The Minister of the Interior and Safety; entry is restricted strictly to military armed forces

Explanation

Article 23 of the Framework Act on Fire Services empowers the fire commander at the scene (소방대장) to designate a Fire Operations Zone and to restrict entry to persons prescribed by Presidential Decree. Article 8 of the Enforcement Decree lists them: owners, managers or occupants of the property inside the zone; electricity, gas, water, telecommunications and transport workers needed for the response; doctors, nurses and other rescue and emergency medical workers; accredited news reporters; investigating officers; and anyone else the fire commander permits.

Question 42Korean fire legislation and administrative principles

Under the Act on Fire Investigation by Fire Services (소방의 화재조사에 관한 법률), when must a fire investigation be commenced, and which body of matters does it cover?

  1. Commenced without delay once the fire authority becomes aware of the fire; it covers the cause of the fire, casualties and property damage, the response activity, and the installation, management and operation of the firefighting systems Correct answer.
  2. Initiated only after total flame extinguishment; comprises Criminal Interrogation and Insurance Appraisal
  3. Initiated within 30 days after the fire; comprises Structural Demolition and Property Foreclosure
  4. Initiated upon request of building insurers; comprises Product Liability Review and Environmental Impact

Explanation

Article 5 of the Act on Fire Investigation by Fire Services requires the head of the fire agency to conduct a fire investigation without delay once the occurrence of a fire becomes known, so that the investigation runs alongside firefighting rather than waiting for extinguishment. Article 3 of the Enforcement Decree sets the scope: the cause of the fire; casualties and property damage; the response activity; the installation, management and operation of firefighting systems; and the fire-risk characteristics of the building or structure involved. The older two-part framing of 원인조사 and 피해조사 comes from the superseded provisions of the Framework Act on Fire Services.

Question 43Korean fire legislation and administrative principles

Under Article 2 of the Act on Installation and Management of Firefighting Systems (소방시설 설치 및 관리에 관한 법률), into which category are Connecting Standpipe Systems (연결송수관설비) and Mechanical Smoke Exhaust Systems (제연설비) classified?

  1. Extinguishing Systems (소화설비)
  2. Alarm Systems (경보설비)
  3. Firefighting Activity Systems (소화활동설비) Correct answer.
  4. Evacuation and Life Rescue Systems (피난구조설비)

Explanation

Firefighting Systems are categorized into 5 groups: Extinguishing, Alarm, Evacuation/Rescue, Water Supply, and Firefighting Activity Systems. Firefighting Activity Systems (소화활동설비) assist responding firefighters during operations, comprising 제연설비 (Smoke Exhaust), 연결송수관설비 (Standpipe Siamese), 연결살수설비, 비상콘센트설비 (Emergency Power Outlets), 무선통신보조설비 (Radio Auxiliary), and 연소방지설비.

Question 44Korean fire legislation and administrative principles

What is the statutory difference between an Operational Check (작동점검) and a Comprehensive Check (종합점검) in the self-inspection regime of the Act on Installation and Management of Firefighting Systems?

  1. An Operational Check verifies, by artificially actuating the equipment, that the firefighting systems operate normally, whereas a Comprehensive Check additionally audits whether the principal components conform to the fire safety technical codes and the relevant Building Act requirements Correct answer.
  2. An Operational Function Check is conducted by the municipal fire chief, whereas a Comprehensive Precision Inspection is conducted by insurance adjusters
  3. An Operational Function Check is performed once every 5 years, whereas a Comprehensive Precision Inspection is conducted monthly
  4. An Operational Function Check applies only to residential homes, whereas a Comprehensive Precision Inspection applies to construction sites

Explanation

Self-inspection (자체점검) is divided into the Operational Check (작동점검), in which the systems are artificially actuated to confirm normal operation, and the Comprehensive Check (종합점검), which includes the operational check and additionally examines whether the structure and performance of the principal components of each system conform to the fire safety performance and technical codes (NFPC / NFTC) and the applicable Building Act standards. The 2022 amendment renamed the two categories from the former 작동기능점검 and 종합정밀점검.

Question 45Korean fire legislation and administrative principles

Under the Enforcement Rules of the Act on Installation and Management of Firefighting Systems, which facility is subject to an annual Comprehensive Check (종합점검)?

  1. Any specific firefighting target object fitted with an automatic sprinkler system Correct answer.
  2. Any residential apartment building equipped solely with fire extinguishers
  3. A 2-story office building equipped only with standalone battery smoke alarms
  4. An agricultural greenhouse equipped with manual hose reels

Explanation

Any specific firefighting target object fitted with an automatic sprinkler system is subject to the Comprehensive Check (종합점검) regardless of total floor area. The other principal triggers are water-spray and equivalent systems on objects of 5,000 m² or more, certain multi-use premises of 2,000 m² or more, and public institutions of 1,000 m² or more equipped with indoor hydrants or automatic fire detection systems. Korean terminology: 스프링클러설비가 설치된 특정소방대상물.

Question 46Korean fire legislation and administrative principles

For a building subject to an annual Comprehensive Check (종합점검), in which calendar period must the check be carried out?

  1. Within the calendar month that includes the anniversary of the building's building usage approval / completion date Correct answer.
  2. Always between December 1 and December 31 of each fiscal year
  3. Exactly 180 days after the building owner's corporate tax filing
  4. At any time within the first quarter (January to March)

Explanation

The Comprehensive Check is carried out in the month containing the anniversary of the building's usage approval date (사용승인일이 속하는 달). Where a building is subject to both checks, the Operational Check is then carried out in the month falling six months after the Comprehensive Check. Korean terminology: 사용승인일이 속하는 달의 말일까지.

Question 47Korean fire legislation and administrative principles

Under Article 23 of the Act on Installation and Management of Firefighting Systems, within how many days following the completion of a self-inspection (자체점검) must the building owner or managing party submit the inspection result report to the competent local Fire Station Chief (소방서장)?

  1. Within 7 days
  2. Within 15 days Correct answer.
  3. Within 30 days
  4. Within 60 days

Explanation

The building owner, manager, or designated entity must submit the firefighting facilities self-inspection result report (자체점검결과보고서) to the competent Fire Chief or Fire Commissioner within 15 days from the inspection completion date (or file electronically via the integrated inspection portal).

Question 48Korean fire legislation and administrative principles

Under Article 24 of the Act on Fire Prevention and Safety Management (화재의 예방 및 안전관리에 관한 법률), which building is classified as a Special Class Fire Safety Management Target (특급 소방안전관리대상물)?

  1. An apartment building of 50 or more storeys excluding basement levels, or 200 m or higher Correct answer.
  2. A 5-story commercial shopping arcade with floor area of 5,000 m²
  3. An apartment complex consisting of two 15-story residential towers
  4. A detached single-family residential timber house

Explanation

Annex 4 to the Enforcement Decree of the Fire Prevention Act sets three special-class (특급) criteria: an apartment building of 50 or more storeys excluding basement levels, or 200 m or higher; a non-apartment object of 30 or more storeys including basement levels, or 120 m or higher; and any other non-apartment object with a gross floor area of 100,000 m² or more.

Question 49Korean fire legislation and administrative principles

Under the Act on Fire Prevention and Safety Management, within how many days must a Fire Safety Manager (소방안전관리자) be appointed upon vacancy, and within how many days from appointment must the owner report this to the competent Fire Chief?

  1. Appointment within 30 days; Report to Fire Chief within 14 days Correct answer.
  2. Appointment within 14 days; Report to Fire Chief within 30 days
  3. Appointment within 60 days; Report to Fire Chief within 7 days
  4. Appointment within 10 days; Report to Fire Chief within 3 days

Explanation

Under Article 24 of the Fire Prevention Act: A Fire Safety Manager must be appointed within 30 days from the date of vacancy (resignation, dismissal, or building usage approval). Once appointed, the building owner/managing party must report the appointment to the competent Fire Chief within 14 days.

Question 50Korean fire legislation and administrative principles

Under Article 25 of the Act on Fire Prevention and Safety Management (화재의 예방 및 안전관리에 관한 법률), which specific firefighting target object is legally required to appoint an Assistant Fire Safety Manager (소방안전관리보조자)?

  1. A detached commercial retail shop with a floor area of 1,000 m²
  2. An apartment complex comprising 300 or more households (or non-apartment building with gross floor area ≥ 15,000 m²) Correct answer.
  3. A rural agricultural storage shed storing unhusked rice
  4. A 2-story detached suburban single-family dwelling

Explanation

Under Article 25 of the Fire Prevention Act, an Assistant Fire Safety Manager (소방안전관리보조자) must be appointed for: 1. Apartment complexes with 300 or more households (plus 1 assistant per additional 300 households); 2. Non-apartment specific firefighting objects with gross floor area ≥ 15,000 m² (plus 1 per additional 15,000 m²); and 3. Dormitories, medical facilities, elderly and child welfare facilities, and night-occupancy accommodations.