NFSC Sub-Officer Entrance cheat sheet

Fire tetrahedron: fuel, oxygen (≥16% for flaming combustion), heat, and the uninhibited chain reaction; removing any one side extinguishes the fire.

Flash point = lowest temperature at which a liquid gives off enough vapour to ignite momentarily; fire point is the higher temperature at which vapour burns continuously once ignited.

Flammable liquid classification (NFPA): Class IA flash point <22.8°C and boiling point <37.8°C; IB flash point <22.8°C with boiling point ≥37.8°C; IC flash point 22.8–37.8°C.

Spontaneous heating requires a material with low heat loss (large surface-to-mass ratio, insulation) and an exothermic oxidation or decomposition reaction; pile size, moisture and ventilation control it.

Backdraught: oxygen-deficient compartment fire admits air, and unburnt fuel gases ignite explosively; indicators are smoke-stained windows, pulsing smoke, and no visible flame.

Flashover occurs when compartment gases reach roughly 500–600°C and radiate enough heat to ignite all combustible contents simultaneously.

Heat release rate Q (kW) = mass loss rate (kg/s) × effective heat of combustion (kJ/g) × combustion efficiency; it drives smoke production and sprinkler activation.

Water absorbs about 2.26 MJ per kg at vaporisation (latent heat), plus sensible heat; steam expansion of roughly 1,700 times the water volume displaces oxygen and cools gases.

Incident command: one incident commander sets strategy; sectors/divisions handle operations, and span of control is normally 3–7 (ideal 5) direct reports.

Offensive mode attacks the fire from inside with a known entry/exit; defensive mode is exterior, master-stream, and excludes interior crews.

BA wearers work in pairs or more with a minimum of two entry-control personnel; entry control records cylinder pressure, time in, and time out.

Tactical ventilation must be coordinated with fire attack; uncoordinated positive-pressure ventilation can push fire into uninvolved spaces.

Water supply: a 45 mm hose delivers roughly 450–900 L/min, a 70 mm hose roughly 1,000–1,900 L/min depending on pressure; estimate hydrant flow before committing lines.

Salvage and overhaul follow knockdown: check for hidden fire with thermal imaging, secure utilities, and preserve evidence where the cause is suspicious.

Mayday procedure: transmit 'Mayday' with name, location, situation and resources needed, then activate the PASS device and stay low; radio silence is maintained for the mayday traffic.

Pump theory: theoretical flow is displaced volume × speed; actual flow is lower because of slip, and pump efficiency = actual/theoretical output.

Centrifugal pump cavitation occurs when NPSH available falls below NPSH required; symptoms are noise, vibration and falling pressure, and the cure is reducing lift or speed.

Relief valve on a pump set to 10% above the maximum working pressure, plus a thermal relief and a pressure gauge on each delivery outlet.

Nozzle reaction force (N) ≈ 2 × flow (L/min) × √pressure (bar) / 60 for a smooth-bore nozzle; it must be controlled when working from ladders or aerial platforms.

Foam proportioning: 3% concentrate for hydrocarbon fuels, 6% for polar solvents (alcohol-resistant foam); an aspirating branch produces the expanded blanket.

BA cylinder duration (minutes) ≈ cylinder volume (L) × pressure (bar) / consumption rate (L/min at ambient); always deduct a safety margin of at least 25%.

Ladders: the 45° angle gives maximum stability; the 4:1 rule means the base is set out one unit for every four units of working height.

Five construction classes: Type I fire-resistive, Type II non-combustible, Type III ordinary (exterior masonry, combustible interior), Type IV heavy timber, Type V wood-frame.

Structural fire resistance is stated in minutes; a 60-minute rated element resists a standard test fire, not an identical real fire.

Truss and lightweight engineered timber floors fail suddenly under fire; crews should not work above a fire in these buildings.

Spalling of concrete and mortar joints under high heat exposes reinforcement and can cause premature collapse.

Dead load is the structure's own weight; live load is occupants and contents; wind and fire are environmental loads.

Smoke control: natural venting relies on buoyancy through roof vents, while mechanical smoke extract uses fans sized to the design fire; pressure differential systems protect stairwells.

Fire doors must be self-closing and latched; hold-open devices must release on alarm, and gaps around the leaf must not be wedged open.

Means of escape: travel distance, protected routes, exit width and signage must allow occupants to reach a place of safety without passing through a fire risk.

Active protection includes detection, alarm, sprinklers and suppression; passive protection includes compartmentation, fire doors, and structural fire resistance.

Sprinkler design density (mm/min) × area of operation (m²) gives the design flow; a single head typically controls a fire in its early stage.

Hot work permit controls welding, grinding and cutting: remove combustibles, use a fire watch, and check the area for at least 60 minutes after work ends.

Housekeeping rule: keep at least 1 m clearance below sprinkler heads and keep escape routes and fire exits unobstructed and unlocked from the inside.

Fire risk assessment steps: identify hazards, identify people at risk, evaluate and reduce risk, record findings, and review periodically.

ERG guide approach: identify the UN number, use the placard class, then apply isolation and protective-action distances from the guide page.

DOT/UN hazard classes: 1 explosives, 2 gases, 3 flammable liquids, 4 flammable solids, 5 oxidisers, 6 toxic, 7 radioactive, 8 corrosive, 9 miscellaneous.

BLEVE: a pressurised liquid container exposed to fire fails catastrophically; cool the vessel from a distance behind cover, and never approach the ends of a tank.

Water-reactive materials (e.g. alkali metals, calcium carbide) liberate flammable gas or heat on contact with water; use dry powder or inert gas instead.

LPG is heavier than air and pools in low areas; natural gas and hydrogen are lighter and accumulate at high points.

Class D metal fires need dry powder or sand; CO2 reacts with some metals and water can intensify the reaction.

Asbestos and silica dust require respiratory protection and wet suppression; contaminated PPE must be bagged and decontaminated before removal.

Scene safety first: isolate, secure the area, and establish an inner and outer cordon before committing rescue teams.

Vehicle extrication: stabilise the vehicle, disconnect the battery, then use glass management, door displacement, roof removal and dash roll in that order.

Confined space entry requires atmospheric testing (oxygen 19.5–23.5%, flammable gas below 10% LEL, toxic gas within limits), a permit, a rescue plan and a standby person.

Trench rescue: slope or shore the sides, keep personnel out of the collapse zone, and never enter an unprotected trench deeper than 1.2 m.

Rope rescue systems use a main line, a belay line and a redundant anchor; the safety factor for life-safety rope is normally 10:1.

Casualty handling: primary survey (DRABC - danger, response, airway, breathing, circulation) precedes the secondary survey and packaging for transport.

Water rescue: reach, throw, row, go - in that order; a rescuer entering the water needs a personal flotation device and a shore tether.

Pressure = force / area; 1 bar = 100 kPa = 14.5 psi; 1 m head of water ≈ 0.098 bar.

Flow rate Q = area × velocity; for a 70 mm hose with 50 mm bore, area = π(0.025)² ≈ 0.00196 m².

Friction loss in hose (bar) ≈ k × Q² × L, where k depends on hose diameter and Q is flow in hundreds of L/min per 100 m.

Pump output in L/min = cylinder displacement (L) × speed (rpm) × volumetric efficiency.

Triangle area = ½ × base × height; circle area = πr²; volume of a cylinder = πr²h.

Percentage concentration: amount of solute / total solution × 100; foam dilution 3% means 3 L concentrate per 100 L of solution.

Convert temperature: °F = (°C × 9/5) + 32; absolute temperature in kelvin = °C + 273.

Combustion is an exothermic redox reaction; the fire triangle adds a fourth element, the chain reaction, for flaming combustion.

Heat transfer modes: conduction (solid contact), convection (fluid movement), radiation (electromagnetic, proportional to T⁴ by Stefan-Boltzmann).

Charles's law: at constant pressure, gas volume is proportional to absolute temperature; Boyle's law: pressure × volume is constant at constant temperature.

The pH scale runs 0–14; below 7 is acidic, above 7 is alkaline, and strong acids or alkalis are corrosive hazards.

Oxidation states and reactivity: oxidisers supply oxygen to a fire, so they must be stored away from fuels and reducing agents.

Electrical hazard: water conducts only when it contains dissolved ions; de-energise before applying water to electrical equipment unless a CO2 or dry-powder agent is used.

Ideal gas law PV = nRT links pressure, volume, amount and temperature; it explains pressure rise in sealed containers exposed to fire.

Reading comprehension: locate the topic sentence, then the supporting evidence; answers must be supported by the passage, not by outside knowledge.

Inference questions ask what the passage implies; eliminate options that are true in general but not stated or implied in the text.

Active voice is preferred in operational writing: 'Close the valve' rather than 'The valve should be closed by the operator'.

Punctuation: use a comma to separate an introductory clause and a semicolon to join two related independent clauses.

Vocabulary in context: choose the meaning that fits the sentence, not the most common dictionary sense of the word.

Report writing: chronological order, factual statements, times and locations, and no opinion or speculation.

Emergency numbers vary by country; in India 112 is the national emergency number and 101 the fire service number.

The National Disaster Management Authority (NDMA) coordinates disaster response in India; the NDRF is its specialised response force.

The Fire Services are a state subject in India under the Constitution; municipal fire brigades operate under state fire rules.

Key statutes: the National Building Code of India (NBC) Part 4 covers fire and life safety; the Factories Act and state fire rules govern industrial premises.

International frameworks: the Sendai Framework for Disaster Risk Reduction 2015–2030 sets global targets for reducing disaster losses.

The Fire Safety Officer's role includes enforcement, inspection, public education and post-incident investigation support.

Reasoning: syllogism - draw conclusions only from the premises given; a conclusion must hold in every valid arrangement of the premises.

Series completion: find the arithmetic or geometric difference, or the alternating pattern, before selecting the next term.

Coding-decoding: map each letter to its numeric position (A=1 … Z=26) and test the shift consistently across all letters.

Direction sense: draw the path on paper and track net displacement; left and right reverse when the person turns to face the opposite direction.

Current affairs: track national disaster-management policy, major fire incidents and their causes, and updates to the National Building Code.

Data interpretation: read the axis labels and units first, then calculate the ratio or percentage change requested.

Pressure = force / area; 1 bar = 100 kPa = 14.5 psi; 1 m head of water ≈ 0.098 bar.

Flow rate Q = area × velocity; for a 70 mm hose with 50 mm bore, area = π(0.025)² ≈ 0.00196 m².

Friction loss in hose (bar) ≈ k × Q² × L, where k depends on hose diameter and Q is flow in hundreds of L/min per 100 m.

Pump output in L/min = cylinder displacement (L) × speed (rpm) × volumetric efficiency.

Triangle area = ½ × base × height; circle area = πr²; volume of a cylinder = πr²h.

Percentage concentration: amount of solute / total solution × 100; foam dilution 3% means 3 L concentrate per 100 L of solution.

Convert temperature: °F = (°C × 9/5) + 32; absolute temperature in kelvin = °C + 273.

Combustion is an exothermic redox reaction; the fire triangle adds a fourth element, the chain reaction, for flaming combustion.

Heat transfer modes: conduction (solid contact), convection (fluid movement), radiation (electromagnetic, proportional to T⁴ by Stefan-Boltzmann).

Charles's law: at constant pressure, gas volume is proportional to absolute temperature; Boyle's law: pressure × volume is constant at constant temperature.

The pH scale runs 0–14; below 7 is acidic, above 7 is alkaline, and strong acids or alkalis are corrosive hazards.

Oxidation states and reactivity: oxidisers supply oxygen to a fire, so they must be stored away from fuels and reducing agents.

Electrical hazard: water conducts only when it contains dissolved ions; de-energise before applying water to electrical equipment unless a CO2 or dry-powder agent is used.

Ideal gas law PV = nRT links pressure, volume, amount and temperature; it explains pressure rise in sealed containers exposed to fire.

Reading comprehension: locate the topic sentence, then the supporting evidence; answers must be supported by the passage, not by outside knowledge.

Inference questions ask what the passage implies; eliminate options that are true in general but not stated or implied in the text.

Active voice is preferred in operational writing: 'Close the valve' rather than 'The valve should be closed by the operator'.

Punctuation: use a comma to separate an introductory clause and a semicolon to join two related independent clauses.

Vocabulary in context: choose the meaning that fits the sentence, not the most common dictionary sense of the word.

Report writing: chronological order, factual statements, times and locations, and no opinion or speculation.

Emergency numbers vary by country; in India 112 is the national emergency number and 101 the fire service number.

The National Disaster Management Authority (NDMA) coordinates disaster response in India; the NDRF is its specialised response force.

The Fire Services are a state subject in India under the Constitution; municipal fire brigades operate under state fire rules.

Key statutes: the National Building Code of India (NBC) Part 4 covers fire and life safety; the Factories Act and state fire rules govern industrial premises.

International frameworks: the Sendai Framework for Disaster Risk Reduction 2015–2030 sets global targets for reducing disaster losses.

The Fire Safety Officer's role includes enforcement, inspection, public education and post-incident investigation support.

Reasoning: syllogism - draw conclusions only from the premises given; a conclusion must hold in every valid arrangement of the premises.

Series completion: find the arithmetic or geometric difference, or the alternating pattern, before selecting the next term.

Coding-decoding: map each letter to its numeric position (A=1 … Z=26) and test the shift consistently across all letters.

Direction sense: draw the path on paper and track net displacement; left and right reverse when the person turns to face the opposite direction.

Current affairs: track national disaster-management policy, major fire incidents and their causes, and updates to the National Building Code.

Data interpretation: read the axis labels and units first, then calculate the ratio or percentage change requested.