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NIMASA STCW FPFF practice questions

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Question 1Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Under the fire triangle, which three elements must be present together for a fire to start and continue burning?

  1. Fuel, oxygen and a source of heat Correct answer.
  2. Fuel, carbon dioxide and a spark
  3. Fuel, nitrogen and a catalyst
  4. Water, oxygen and heat

Explanation

The fire triangle states that combustion needs three components at the same time: combustible fuel, oxygen from the air and enough heat to reach the material's ignition temperature. Removing any one side of the triangle stops the fire, which is the principle behind cooling, smothering and starvation as extinguishing methods.

Question 2Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

The fire tetrahedron adds a fourth element to the fire triangle. Which element is added?

  1. A chemical chain reaction Correct answer.
  2. A pressurised fuel supply
  3. Ambient humidity
  4. A source of static electricity

Explanation

The tetrahedron adds the uninhibited chemical chain reaction that sustains flaming combustion to fuel, oxygen and heat. This fourth side explains why chemical extinguishing agents such as clean agents and dry powder can break the reaction even when fuel and oxygen remain present.

Question 3Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

A fire on board is being extinguished by closing all openings to the compartment so that the oxygen level falls. Which side of the fire triangle is being removed?

  1. Oxygen Correct answer.
  2. Heat
  3. Chain reaction
  4. Fuel

Explanation

Closing the openings limits the supply of fresh air, so the oxygen concentration in the space drops below the level needed for flaming combustion. This is the smothering principle and it attacks the oxygen side of the fire triangle rather than the fuel or heat side.

Question 4Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Which of the following is classified as a chemical ignition source in shipboard fire theory?

  1. An electrical short circuit
  2. Spontaneous heating of oily rags Correct answer.
  3. A hot exhaust manifold
  4. Friction from a running belt

Explanation

Spontaneous heating occurs when materials such as oil-soaked rags or coal oxidise slowly and the heat generated cannot escape, eventually raising the material to its ignition temperature. It is chemical because the heat arises from an exothermic reaction within the material itself. The other options are physical or electrical sources of heat.

Question 5Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

A fuel oil spray from a fractured pipe lands on an unlagged exhaust pipe at about 400 degrees Celsius and ignites without any flame. What ignition process has occurred?

  1. Ignition by a static discharge
  2. Catalytic ignition by rust
  3. Auto-ignition from a hot surface Correct answer.
  4. Spontaneous combustion of the oil

Explanation

When a fuel is heated by contact with a hot surface until it reaches its auto-ignition temperature, it ignites without an external flame. Unlagged exhaust pipes and similar hot surfaces are a well-known ignition source in engine rooms. Spontaneous combustion instead involves internal oxidation of the material itself.

Question 6Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Which statement best describes the flashpoint of a liquid fuel?

  1. The lowest temperature at which the liquid gives off enough vapour to form an ignitable mixture near its surface Correct answer.
  2. The temperature at which the vapour pressure equals atmospheric pressure
  3. The temperature at which the liquid itself begins to burn steadily
  4. The temperature at which the liquid solidifies

Explanation

Flashpoint is the lowest temperature at which a liquid releases sufficient vapour to form a flammable mixture with air that can be ignited by an external source. Flammable liquids with low flashpoints, such as petrol, present a fire risk at normal shipboard temperatures. Flashpoint concerns vapour generation, not sustained burning of the liquid.

Question 7Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

During the early stage of a compartment fire, temperatures are low and combustion is incomplete, producing large amounts of carbon monoxide and soot. What is this stage called?

  1. The fully developed stage
  2. The flashover stage
  3. The decay stage
  4. The incipient stage Correct answer.

Explanation

In the incipient stage the fire is small, oxygen is still plentiful and combustion is inefficient, so smoke and carbon monoxide are produced in quantity. This stage is the easiest to extinguish and is when detection matters most. Flashover and the fully developed stage occur later as heat output rises sharply.

Question 8Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

What is flashover in a compartment fire?

  1. The point at which the fire is finally extinguished
  2. The slow cooling of the compartment after the fuel is consumed
  3. The moment a fire is first detected by a smoke detector
  4. The sudden transition in which all combustible surfaces in the space ignite almost simultaneously Correct answer.

Explanation

Flashover is the rapid transition from a growing fire to a fully developed fire, when heat feedback causes all exposed combustible surfaces to ignite nearly at once. Temperatures rise steeply and the compartment becomes untenable, which is why crews must not open a hot compartment without control. It is a fire development event, not a detection or extinguishing event.

Question 9Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

A firefighter opens the door of a compartment that is hot and full of unburnt smoke, and a fireball erupts into the space. Which phenomenon does this describe?

  1. A flashover
  2. A backdraught Correct answer.
  3. A smouldering fire
  4. A boiling liquid expanding vapour explosion

Explanation

A backdraught occurs when air is admitted to an oxygen-starved compartment containing hot, fuel-rich smoke, and the sudden mixing ignites the gases explosively. It is a risk when an enclosed space has been burning with limited ventilation. Flashover instead involves the ignition of surfaces through heat build-up in a growing fire.

Question 10Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Which class of fire involves flammable liquids such as diesel oil and lubricating oil?

  1. Class A
  2. Class B Correct answer.
  3. Class D
  4. Class C

Explanation

Class B fires involve flammable and combustible liquids, including fuel oils and lubricating oils found in machinery spaces. Class A covers solid combustibles, Class C covers flammable gases and Class D covers combustible metals. Correct classification determines the extinguishing agent selected.

Question 11Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Which extinguishing medium acts primarily by smothering a flammable liquid fire and forming a vapour-excluding blanket on the surface?

  1. Aqueous film-forming foam Correct answer.
  2. Water jet
  3. Dry sand
  4. Carbon dioxide

Explanation

Aqueous film-forming foam spreads a film over the burning liquid surface, excluding air and suppressing vapour release, and it also cools the fuel. This makes foam the preferred agent for spill fires involving fuel oils and similar liquids. A solid water jet can spread the burning liquid rather than extinguish it.

Question 12Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Why must a fire involving a combustible metal such as magnesium not be attacked with a water jet?

  1. Water conducts electricity from the metal
  2. Water freezes on contact with the hot metal
  3. Water boils too slowly to cool the metal
  4. The metal can react with water to release hydrogen and intensify the fire Correct answer.

Explanation

Certain reactive metals react with water at high temperature, generating hydrogen gas and releasing further heat, which can cause violent intensification or explosion. Combustible metal fires therefore require a special dry powder or dry sand that smothers the surface. This is why metal fires are treated as a separate class.

Question 13Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

In fire chemistry, what is the role of oxygen in combustion?

  1. It is a catalyst that is not consumed
  2. It is the oxidising agent that reacts with the fuel and releases heat Correct answer.
  3. It is an inert gas that dilutes the fire
  4. It is a fuel that burns in the presence of air

Explanation

Oxygen is the oxidant that combines chemically with the fuel during combustion, releasing heat and light. Air normally supplies the oxygen, and reducing its concentration below the level needed for combustion stops flaming. Oxygen itself is not a fuel and is consumed in the reaction.

Question 14Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Why is carbon monoxide especially dangerous in a shipboard fire?

  1. It is toxic and binds to haemoglobin, preventing oxygen transport in the blood Correct answer.
  2. It is a visible black smoke that blocks vision
  3. It has a strong irritant smell that causes choking
  4. It is an oxidising gas that accelerates combustion

Explanation

Carbon monoxide is colourless and odourless and binds strongly to haemoglobin, so the blood cannot carry oxygen. Inhaled in a smoke-filled compartment it can cause rapid loss of consciousness and death, often before the fire reaches the person. This is why breathing apparatus and prompt evacuation are essential.

Question 15Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

A compartment fire is burning steadily with adequate ventilation. The crew closes the door and the fire gradually reduces in intensity. Which change best explains this?

  1. The oxygen concentration in the compartment falls below the level supporting flaming combustion Correct answer.
  2. The carbon dioxide level rises and acts as a fuel
  3. The fuel in the compartment is entirely consumed
  4. The heat release rate increases and suppresses the flames

Explanation

In a ventilation-controlled space, closing the door limits fresh air and the oxygen level falls until flaming combustion can no longer be sustained. The fire may then smoulder and produce large amounts of unburnt smoke, creating a backdraught risk if air is later admitted. Fuel is not necessarily consumed and carbon dioxide does not act as fuel.

Question 16Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Which of the following is an example of a mechanical ignition source in a ship's engine room?

  1. A short circuit in a lighting circuit
  2. Sparks produced by friction between a slipping belt and pulley Correct answer.
  3. Heat from a galley cooking range
  4. Slow oxidation of a pile of oily rags

Explanation

Mechanical ignition sources produce heat or sparks through friction, impact or compression, such as a slipping belt rubbing on a pulley or metal striking metal. These sources are controlled by maintenance, guards and the use of non-sparking tools in hazardous areas. The other options are thermal, electrical or chemical sources.

Question 17Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

What is the lower flammable limit of a fuel vapour?

  1. The temperature at which the vapour condenses
  2. The maximum vapour concentration that will not ignite
  3. The minimum vapour concentration in air below which the mixture will not ignite Correct answer.
  4. The pressure at which the vapour becomes a liquid

Explanation

The lower flammable limit is the leanest vapour-air mixture that can still be ignited; below it there is too little fuel to support combustion. The upper flammable limit is the richest ignitable mixture. The range between the two limits defines the flammable or explosive range of the fuel.

Question 18Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

A tank containing heavy fuel oil is being heated. Why does this increase the fire risk?

  1. Heating raises the vapour concentration towards the flammable range Correct answer.
  2. Heating reduces the oxygen content of the tank
  3. Heating converts the oil into an inert gas
  4. Heating lowers the flashpoint of the oil permanently

Explanation

Raising the temperature of a liquid increases the vapour it gives off, so the vapour concentration in the tank ullage can move into the flammable range. This is why cargo and fuel heating must be controlled and why inert gas systems are used on tankers. The flashpoint of a given oil does not change permanently with normal heating.

Question 19Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Which combination correctly matches an extinguishing method to the side of the fire triangle it removes?

  1. Water spray removes heat; foam blanket excludes oxygen Correct answer.
  2. Water spray removes fuel; foam blanket removes heat
  3. Foam blanket breaks the chain reaction; clean agent excludes oxygen
  4. Water spray breaks the chain reaction; clean agent removes fuel

Explanation

Water spray absorbs heat and cools the fuel below its ignition temperature, while a foam blanket separates the fuel from the oxygen in the air. These are the cooling and smothering principles respectively. Chemical agents act by breaking the chain reaction, which is a separate mechanism.

Question 20Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Smoke and hot gases spread rapidly along corridors and stairways during a shipboard fire. Which principle explains this?

  1. Cool air sinks and pushes smoke downwards into the bilges
  2. Combustion products are chemically inert and spread evenly
  3. Smoke is heavier than air and flows along the deck
  4. Thermal expansion and buoyancy drive hot gases through openings and ventilation routes Correct answer.

Explanation

Hot combustion gases expand and rise because of buoyancy, then spread through openings, stairways and ventilation ducts, carrying heat and toxic products well ahead of the flames. This is why smoke control and closing fire doors are critical. Smoke is not heavier than air at fire temperatures and it is far from inert.

Question 21Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

A crew member reports a smell of hot oil near an electrical distribution board. Which ignition risk does an overheated electrical connection primarily represent?

  1. A mechanical ignition source from friction
  2. A chemical ignition source from spontaneous heating
  3. A smothering hazard from oxygen depletion
  4. An electrical ignition source that can ignite nearby combustible material Correct answer.

Explanation

Overheated connections, loose terminals and faulty insulation are electrical ignition sources: resistance heating or arcing can raise nearby material to its ignition temperature. Good maintenance and correct fusing reduce this risk. Spontaneous heating and friction are separate categories.

Question 22Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Which statement about the fire triangle is correct when a fire has been extinguished by removing the fuel?

  1. The fire continues until the heat is removed as well
  2. The fire stops only if the oxygen level also falls
  3. The fire stops because one side of the triangle has been removed Correct answer.
  4. The fire stops only after the chain reaction is broken chemically

Explanation

The triangle model holds that removing any single side, whether fuel, oxygen or heat, is sufficient to stop combustion. Starving the fire of fuel therefore extinguishes it without the need to cool or smother. Chemical chain reaction breaking is an additional mechanism described by the tetrahedron.

Question 23Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Which of the following best explains why a fire in a closed compartment can reignite after being apparently extinguished?

  1. The fire triangle is permanently broken once flames are no longer visible
  2. Carbon dioxide produced by the fire acts as a fuel on re-entry
  3. Hot surfaces and smouldering material can re-ignite when fresh air is admitted Correct answer.
  4. The oxygen level inside the compartment rises permanently

Explanation

Flames disappearing in an oxygen-starved space does not mean the fire is out; hot metal and smouldering fuel can reignite when air is admitted. This is why compartments are cooled, monitored and ventilated with care before entry. The fire triangle is not permanently broken merely because visible flame is gone.

Question 24Shipboard fire theory: the fire triangle/tetrahedron, ignition sources, and fire chemistry

Which product of combustion is primarily responsible for the blackening of surfaces and the reduction of visibility in a shipboard fire?

  1. Nitrogen
  2. Carbon dioxide
  3. Water vapour
  4. Soot particles Correct answer.

Explanation

Soot consists of fine carbon particles formed during incomplete combustion, and it darkens surfaces and scatters light so that visibility falls sharply. It also carries heat and can be a significant respiratory hazard. Water vapour, nitrogen and carbon dioxide are not visible blackening agents.

Question 25Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

On a tanker, which property of a flammable liquid determines the lowest temperature at which it releases enough vapour to form an ignitable mixture near its surface?

  1. Flashpoint Correct answer.
  2. Specific gravity
  3. Auto-ignition temperature
  4. Viscosity

Explanation

The flashpoint is the lowest temperature at which a liquid gives off sufficient vapour to form an ignitable mixture with air close to its surface. It is the key classification value used to judge fire and explosion risk of petroleum products in STCW fire-prevention training.

Question 26Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Cargo tank cleaning on a product tanker has just finished and the tank atmosphere reads 22% LEL on the combustible gas indicator. What does this reading most directly indicate?

  1. The atmosphere is below the lower explosive limit and cannot ignite
  2. The tank is gas-free and safe for entry without further checks
  3. The atmosphere is above the upper explosive limit but still flammable
  4. The atmosphere is within the flammable range and is unsafe for entry or hot work Correct answer.

Explanation

A reading of 22% LEL means the hydrocarbon concentration is about one-fifth of the lower explosive limit, which lies inside the flammable range and is unsafe for entry or hot work. Any reading above roughly 1% LEL is treated as flammable in tank atmosphere control.

Question 27Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Which condition is required for a flammable gas to ignite?

  1. The gas must be under positive pressure
  2. The gas concentration must lie between its lower and upper flammable limits Correct answer.
  3. The gas must be at or above its flashpoint
  4. The gas must be lighter than air

Explanation

Ignition needs a flammable concentration between the lower and upper flammable limits, plus oxygen and an ignition source. Density relative to air affects where gas accumulates but is not an ignition condition.

Question 28Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

A compartment is being prepared for hot work. Which atmosphere condition must be confirmed before a hot work certificate is issued?

  1. Combustible gas below 50% LEL with forced ventilation running
  2. Combustible gas below 10% LEL with normal oxygen
  3. Combustible gas at 5% LEL with a fire watch posted
  4. Combustible gas at 0% LEL with sufficient oxygen and no toxic risk Correct answer.

Explanation

Hot work requires a gas-free atmosphere, normally confirmed as 0% LEL, together with adequate oxygen and no toxic hazard. Any measurable combustible gas means the space is not safe for welding, cutting or grinding.

Question 29Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Why must a hot work permit be withdrawn and the work stopped if the fire watch leaves the location?

  1. Because continuous fire watch is a condition of the permit and unsupervised hot work removes the immediate fire response Correct answer.
  2. Because the welder must be re-certified each time
  3. Because the permit is only valid for one calendar day
  4. Because ventilation must be switched off during breaks

Explanation

A hot work permit is issued on conditions, and continuous fire watch is one of them. If the watch leaves, the immediate means of detecting and fighting a smouldering fire is gone, so the work must stop and the permit be re-validated.

Question 30Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Which practice best prevents the accumulation of flammable vapour during tank cleaning on a tanker?

  1. Maintaining inert gas or continuous ventilation so the atmosphere stays outside the flammable range Correct answer.
  2. Keeping the tank closed to retain inert gas until cleaning is complete
  3. Opening all tank lids to allow natural draught
  4. Spraying water to dissolve the hydrocarbons

Explanation

Vapour accumulation is prevented by keeping the tank atmosphere either inerted or continuously ventilated so it stays outside the flammable range. Simply opening lids gives unpredictable natural draught and can create flammable pockets.

Question 31Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

A portable electrical tool is to be used in a pump room. Which protection concept is appropriate for that space?

  1. Explosion-proof or intrinsically safe equipment rated for the hazardous zone Correct answer.
  2. An ordinary domestic plug and socket with an earth connection
  3. A tool protected only by a residual current device
  4. A tool fitted with a longer cable so the socket stays outside

Explanation

Pump rooms are hazardous zones where flammable vapour may be present, so only explosion-proof or intrinsically safe equipment rated for that zone may be used. Ordinary tools can produce arcs or hot surfaces that ignite the atmosphere.

Question 32Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

What is the principal fire risk associated with overloaded electrical circuits in accommodation spaces?

  1. Overheating of cables and terminals that can ignite insulation and nearby combustibles Correct answer.
  2. Automatic disconnection of the circuit
  3. Reduced voltage causing dim lighting
  4. Increased power factor in the distribution board

Explanation

Overloading raises conductor temperature, which degrades insulation and can ignite it or adjacent combustible material. Correct circuit protection and avoidance of daisy-chained adaptors are the standard preventive measures.

Question 33Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

During hot work on a bulkhead, a smouldering fire is discovered on the opposite side two hours after the job ends. Which control was most likely missing?

  1. A gas detector at the welder's position
  2. A second welder on standby
  3. Adequate post-work fire watch and inspection of adjacent spaces Correct answer.
  4. A permit signed by the master

Explanation

Heat conducts through steel and can ignite combustible material on the far side long after the work stops. The permit system therefore requires a post-work fire watch and inspection of adjacent spaces for a defined period.

Question 34Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Which item of housekeeping practice most reduces fire risk in a machinery space?

  1. Removing accumulated oil, rags and refuse and keeping the space free of combustible material Correct answer.
  2. Storing spare lubricants beside the switchboard
  3. Painting over oil-stained lagging
  4. Storing oily rags in an open bin near the boiler

Explanation

Good housekeeping removes the fuel that a small ignition source would otherwise consume. Oily rags, accumulated oil and refuse are common fire fuels in machinery spaces and must be removed or stored in covered metal containers.

Question 35Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Why are oily rags a particular fire hazard when left in a heap?

  1. They evaporate and increase the flashpoint of the space
  2. They release toxic gas that ignites on contact with air
  3. Heat generated by oxidation cannot escape and can build up to ignition temperature Correct answer.
  4. They absorb water and become conductive

Explanation

Oil oxidises on the rag surface and produces heat; in a heap this heat cannot dissipate, so the temperature rises until the material self-heats to ignition. Rags should be kept in a covered metal container and disposed of promptly.

Question 36Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

A gas cylinder for oxy-acetylene cutting is stored on deck. Which practice is correct?

  1. Lay acetylene cylinders on their side to save space
  2. Store cylinders next to the paint locker to keep them dry
  3. Store cylinders upright, secured, separated by gas type and away from heat and ignition sources Correct answer.
  4. Store oxygen and acetylene cylinders together in one unventilated locker

Explanation

Cylinders must be kept upright and secured, with oxygen and fuel gas separated and away from heat and ignition sources. Acetylene is unstable and must never be stored or used lying down.

Question 37Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Which statement correctly describes the flammable range of a gas?

  1. It is the range of oxygen concentrations in which combustion stops
  2. It is the concentration range in air between the lower and upper flammable limits Correct answer.
  3. It is the pressure range over which the gas can be compressed
  4. It is the temperature range over which the gas remains liquid

Explanation

The flammable range is the concentration band in air, bounded by the lower and upper flammable limits, within which ignition can occur. Outside that band the mixture is either too lean or too rich to burn.

Question 38Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

A tank is being inerted with flue gas before cargo operations. What is the purpose of keeping the oxygen content below about 8% by volume?

  1. To increase the vapour pressure of the cargo
  2. To reduce the flashpoint of the cargo
  3. To keep the atmosphere too oxygen-poor to support combustion Correct answer.
  4. To prevent the cargo from freezing

Explanation

Inerting lowers the oxygen content so that, even if hydrocarbon vapour is present, the mixture cannot support combustion. Below roughly 8% oxygen by volume, most hydrocarbon atmospheres are outside the flammable range.

Question 39Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Which of the following is a source of ignition that is often overlooked during hot work on deck?

  1. The length of the earth return cable
  2. The hot slag and sparks falling into a bilge or onto paint residues below Correct answer.
  3. The colour of the welding screen
  4. The weight of the electrode holder

Explanation

Sparks and hot slag can fall through openings and ignite residues, paint or rubbish well away from the welder. Screens and covering adjacent spaces are required to control this spread of ignition sources.

Question 40Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

What is the primary reason for bonding and earthing equipment during cargo operations on a tanker?

  1. To increase the pumping rate
  2. To reduce the flashpoint of the cargo
  3. To improve radio reception
  4. To prevent static discharge sparks that could ignite flammable vapour Correct answer.

Explanation

Bonding and earthing equalise potential so that static electricity generated by flow, spraying or settling cannot discharge as a spark. A spark in a flammable atmosphere is a classic tanker ignition scenario.

Question 41Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Before entering a cargo tank that has been ventilated, which combination of readings confirms a safe atmosphere for entry without breathing apparatus?

  1. Oxygen about 21%, combustible gas 0% LEL, toxic gas below the exposure limit Correct answer.
  2. Oxygen 18%, combustible gas 0% LEL, no toxic reading
  3. Oxygen 15%, combustible gas 0% LEL, no toxic reading
  4. Oxygen 21%, combustible gas 5% LEL, toxic gas below the limit

Explanation

Safe entry requires oxygen near 21%, combustible gas at 0% LEL and toxic gases below their exposure limits. Reduced oxygen, even with no combustible gas, is a life-threatening atmosphere.

Question 42Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

A fire in a paint locker is best prevented by which combination of measures?

  1. Storing paint tins loosely on shelves with the door open
  2. Storing thinners in the engine room to keep them warm
  3. Using ordinary light fittings inside the locker
  4. Keeping the locker closed, ventilated, free of ignition sources and fitted with appropriate fire detection Correct answer.

Explanation

A paint locker holds flammable liquids, so it must be kept closed and ventilated, with no ignition sources and with detection and fixed extinguishing arrangements as required. Loose storage and ordinary fittings defeat these controls.

Question 43Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Which situation most clearly demonstrates the danger of a flashback during oxy-acetylene cutting?

  1. The cutting tip becomes warm to the touch
  2. The flame travels back up the torch into the hose and cylinder Correct answer.
  3. The cylinder pressure gauge reads slightly low
  4. The flame burns with a slightly longer cone than usual

Explanation

A flashback is flame travelling back through the torch into the hose and possibly the cylinder, which can cause an explosion. Flashback arrestors on the torch and regulator are fitted to stop this propagation.

Question 44Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

What is the correct response if a strong smell of gas is detected in a compartment containing electrical equipment?

  1. Open the compartment and search for the leak with a lighter
  2. Use a mobile phone to call the engine room from inside the space
  3. Avoid operating electrical switches, evacuate, raise the alarm and isolate power from outside the space Correct answer.
  4. Switch on the ventilation fan to clear the gas

Explanation

Operating any switch, including a fan or phone, can produce a spark in a flammable atmosphere. The correct response is to avoid switching, evacuate, raise the alarm and isolate power from a safe location.

Question 45Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Which factor determines whether a spill of a flammable liquid on a hot deck presents an immediate fire risk?

  1. The colour of the liquid
  2. Whether the deck temperature is at or above the liquid's flashpoint Correct answer.
  3. The volume of the container it came from
  4. The viscosity of the liquid at 0 degrees Celsius

Explanation

A spill becomes dangerous when the surface temperature is at or above the flashpoint, because sufficient vapour is then released to form an ignitable mixture. Cool surfaces may still be hazardous if the liquid is volatile.

Question 46Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Which of the following best describes the role of a fire patrol after hot work has finished?

  1. To test the oxygen content of the workshop
  2. To record the amount of gas consumed
  3. To check that the welder has cleaned the tools
  4. To inspect the work area and adjacent spaces for signs of smouldering fire over a defined period Correct answer.

Explanation

The post-work fire patrol inspects the work area and adjacent spaces for heat, smoke or smouldering material for a defined period after the job ends. This catches concealed ignition caused by conducted heat.

Question 47Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

A crew member wants to use a personal fan with a damaged cable in a cabin. Which action is correct?

  1. Wrap the damaged section with tape and continue using it
  2. Plug it into a multi-adaptor to reduce the load
  3. Use it only when the cabin is unoccupied
  4. Take the fan out of service and report it for repair or replacement Correct answer.

Explanation

Damaged cables expose live conductors and can arc, shock or ignite nearby combustibles. The correct action is to remove the appliance from service and report it so it is repaired or replaced by a competent person.

Question 48Fire hazards and prevention: flammable liquids, gases, electrical hazards, hot work, and housekeeping

Why is spontaneous combustion of coal cargo a particular concern on bulk carriers?

  1. Coal releases flammable gas only when wet
  2. Coal has a flashpoint below zero degrees Celsius
  3. Coal absorbs oxygen slowly, generating heat that can build up in a stockpile to ignition Correct answer.
  4. Coal ignites only when exposed to a naked flame

Explanation

Coal can oxidise slowly, and in a confined stockpile the heat generated cannot escape, so the temperature rises until self-ignition occurs. Monitoring cargo temperature and gas concentrations is the standard control.

Question 49Fire detection and alarm systems, fixed installations, and emergency communications

On a cargo vessel, which device is designed to detect a rapid temperature rise in the accommodation and machinery spaces and automatically sound the fire alarm?

  1. Heat detector Correct answer.
  2. Manual call point
  3. Smoke detector
  4. Sprinkler head

Explanation

Heat detectors respond to a fixed temperature threshold or a defined rate of temperature rise, which is why they suit galleys, laundries and machinery spaces where smoke detectors would give nuisance alarms. Smoke detectors respond to combustion particles, manual call points need a person to break the glass, and a sprinkler head discharges water rather than initiating detection.

Question 50Fire detection and alarm systems, fixed installations, and emergency communications

What is the primary purpose of a manual call point in a ship's fire detection system?

  1. To reset the fire control panel after an alarm
  2. To test the detector circuit without triggering the general alarm
  3. To isolate a faulty detector from the loop
  4. To allow any person to raise the fire alarm manually at the point of discovery Correct answer.

Explanation

Manual call points are placed along escape routes so that anyone discovering a fire can raise the alarm without waiting for automatic detection. They are part of the alarm-initiating circuit, not a testing or isolating device, and resetting is done from the control panel.