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GASCO exit exam questions and answers — Set 3

Set 3 of the Advanced Training for Liquefied Gas Tanker Cargo Operations (GASCO) exit exam bank — 30 of 351 questions, with the correct option marked and a one-line explanation for every one. Read it end to end, jump to a single set, or search it — then sit the same bank as a timed paper. The real DG Shipping exit exam is 30 marks with 15 to pass.

These are the bank's original groupings. Practising deals the whole bank out again every time you reshuffle, so a practice “Set 3” is a different 30 questions each time — the set numbers below are the source file's, and are only used here so the key stays navigable. Options are listed in their original order with fixed letters; when you practise, those move too.

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Set 3 — 30 GASCO exit exam questions with answers

1. Deep well pump shaft bearing are cooled and lubricated by liquid

  • A. Cargo being pumped
  • B. Hydraulic oil
  • C. Greas
  • D. Inert gas
Answer: A — Cargo being pumped
Submerged / deepwell cargo pumps in liquefied gas carriers utilize the liquid cargo being pumped to lubricate and cool the pump bearings and motor windings.

2. The study of behaviour of matter at low temperature is called

  • A. Seismology
  • B. Hydrograph
  • C. Cryogenics
  • D. Ecology
Answer: C — Cryogenics
Cryogenics is the branch of physics and engineering that studies the production and behavior of materials at extremely low cryogenic temperatures (below -150°C / 123 K).

3. Fixed gas detection system alarms should be activated when the vapour concentration reaches

  • A. 20
  • B. 5
  • C. 30
  • D. 60
Answer: B — 5
Fixed gas detection systems on gas tankers are typically set to alarm at 30% LEL in non-enclosed spaces or 5% LEL to 20% LEL depending on zone requirements and sampling configurations.

4. A device fitted in gas vent pipeline to arrest the passage of flame Into enclosed space

  • A. Flame arrestor
  • B. Explosion proof
  • C. Flame screen
  • D. Gas fr
Answer: A — Flame arrestor
A flame arrestor is a safety device fitted in vent lines and pipework designed to prevent the passage of flame into enclosed spaces or cargo tanks by dissipating heat across metallic elements.

5. Chemical combination of flammable substance with oxygen is called

  • A. Explosion
  • B. Auto ignition
  • C. Combustion
  • D. None of the abov
Answer: C — Combustion
The correct answer is Combustion. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

6. Which cargo operation are to be recorded in cargo record book :

  • A. All bunker operations
  • B. All petroleum cargo operations
  • C. All cargo operations involving NLS
  • D. All cargo operations
Answer: D — All cargo operations
Under MARPOL regulations and gas tanker protocols, all cargo and ballast operations involving liquefied gases or noxious liquid substances must be documented in the Cargo Record Book.

7. When cargo carried as liquid in cargo tanks and not shipped in drums , containers , or packages , what are they called as

  • A. Liquid cargo
  • B. Tank cargo
  • C. Oil cargo
  • D. Bulk cargo
Answer: D — Bulk cargo
Cargoes loaded directly into ship tanks without intermediate packaging, drums, or containers are classified as bulk liquid cargoes.

8. Gas ship accommodation and machinery space are :

  • A. Hazardous area
  • B. Gas saf
  • C. Gas dangerous
  • D. All the abov
Answer: B — Gas saf
Accommodation spaces, engine rooms, and service spaces outside the cargo area are designated as Gas Safe areas provided they are properly segregated and maintained at positive pressure.

9. What is the hazards – reactivity when cargo reacts with water called

  • A. Hydrate formation
  • B. Polymerization
  • C. Toxic vapour
  • D. None of the abov
Answer: A — Hydrate formation
Hydrate formation occurs when light hydrocarbons (like methane, ethane, propane) combine with free water at low temperatures and high pressures, forming solid ice-like crystalline compounds that can block valves and pipework.

10. Fire fighting technique with a pool fire is to sweep

  • A. Side to sid
  • B. Front to back
  • C. Both A and B
  • D. None of the abov
Answer: C — Both A and B
When tackling a liquefied gas pool fire with dry chemical powder, the recommended nozzle technique is to sweep side-to-side and advance from front-to-back to extinguish the base of the flame.

11. The mass of a Vapour compared with the mass of an equal volume of air both at standard condition to temp and pressure is

  • A. Relative liquid density
  • B. Relative vapour density
  • C. Relative density
  • D. None of the abov
Answer: B — Relative vapour density
The correct answer is Relative vapour density. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

12. Changing of cargo which may involve

  • A. Only gas freeing
  • B. Only inerting
  • C. Only gassing up
  • D. All of the abov
Answer: D — All of the abov
A complete change of cargo grades on a gas tanker typically involves stripping/warming up, inerting, gas freeing, aerating (if required), and subsequent gassing up/cooling down.

13. On which type of cargo tank would you find a bimetallic joint or STJ

  • A. Kvaerner Moss Type B
  • B. Gas transport membrane
  • C. Type C
  • D. Prismatic Type A
Answer: A — Kvaerner Moss Type B
In Kvaerner Moss Type B spherical tank systems, a structural transition joint (STJ or bimetallic joint) connects the aluminum alloy sphere to the stainless/carbon steel supporting skirt.

14. If the cargo density is different from that specified the float gauge manufacturer what will you adjust

  • A. Float correction
  • B. Trim correction
  • C. List correction
  • D. Tape correction
Answer: A — Float correction
The correct answer is Float correction. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

15. The frequency of pressure testing ashore of BA set should at least every

  • A. 6 years
  • B. 5 years
  • C. 10 years
  • D. 15 years
Answer: B — 5 years
Self-Contained Breathing Apparatus (SCBA/BA) cylinders must undergo periodic hydraulic pressure testing ashore at least once every 5 years in compliance with SOLAS and class rules.

16. What is the guiding rule for limiting pressure surge on loading or discharging

  • A. Stop the cargo pump
  • B. First close ESD valve nearest to the pump
  • C. Finally close other ESD valv
  • D. All the abov
Answer: D — All the abov
To minimize hydraulic pressure surge (liquid hammer), ESD valves and pumps follow sequenced shut-down protocols.

17. The ventilation of the airlock should be of the ______ pressure type

  • A. Negativ
  • B. Positiv
  • C. Neutral
  • D. None of the abov
Answer: B — Positiv
Airlocks providing access between gas-dangerous and gas-safe zones are maintained at positive relative air pressure to prevent vapor ingress into the safe area.

18. Why is it necessary to cool down cargo tanks (refrigerated ships) during bulk loading

  • A. To avoid overflow
  • B. To avoid vapors emission
  • C. To avoid vacuum in cargo tank
  • D. To avoid excessive tank pressure
Answer: D — To avoid excessive tank pressure
Pre-cooling refrigerated cargo tanks avoids thermal shock, violent flashing, and excessive tank pressure increases during bulk loading.

19. An overdose of toxic petroleum vapour effects your sense of smell by

  • A. Reducing it temporarily
  • B. Taking it away completely
  • C. Improving it temporarily
  • D. Improving it permanently
Answer: B — Taking it away completely
High concentrations of hydrocarbon vapors and toxic compounds (like H2S) rapidly cause olfactory fatigue, completely deadening the sense of smell.

20. All liquefied gases produces vapours which have a relative vapour density greater than that of

  • A. Methan
  • B. Methane and ethylen
  • C. Methane, ethylene and ammonia
  • D. None of the abov
Answer: A — Methan
Relative vapor density is the ratio of the mass of a specific volume of gas/vapor compared to an equal volume of dry air at standard temperature and pressure.

21. Gas codes and classification society rules require every tank to be fitted at least _____ level gauge

  • A. On
  • B. Two
  • C. Thr
  • D. Four
Answer: B — Two
Under the IGC Code (Chapter 13), each cargo tank must be fitted with at least two independent level gauging devices.

22. The concentration of a hydrocarbon gas is air below which there is insufficient hydrocarbon is called

  • A. Lower flammable limit
  • B. Dry air
  • C. Upper flammable limit
  • D. Stoichiometric ratio
Answer: A — Lower flammable limit
The Lower Flammable Limit (LFL/LEL) is the minimum concentration of flammable gas/vapor in air below which the mixture is too lean to ignite.

23. After stopping the cargo compressor, the glycol/water system is left running to provide

  • A. Crank case heating
  • B. Remove cargo vapours
  • C. Both a and b
  • D. None of the abov
Answer: C — Both a and b
After shutting down cargo compressors, the glycol-water heating circuit is maintained to provide crankcase heating and prevent condensation or migration of cargo vapors.

24. Fixed water spray system for fire protection purpose in gas tanker covers area such as

  • A. Cargo tanks domes only
  • B. The front of the accommodation and control room bulkhead
  • C. Cargo tank area above deck and cargo manifold area
  • D. All the abov
Answer: D — All the abov
Fixed water spray systems on gas carriers provide boundary cooling for cargo tank domes, deck piping, manifolds, and accommodation forward bulkheads.

25. When carbon atoms joined by double covalent bonds C-C or triple covalent bonds, what is it called as

  • A. Saturated organic compound
  • B. Unsaturated organic compound
  • C. Both a and b
  • D. None of the abov
Answer: B — Unsaturated organic compound
Hydrocarbons containing double (C=C) or triple (C≡C) carbon-carbon bonds (such as ethylene and propylene) are classified as unsaturated organic compounds.

26. What is liquid relative density at atmospheric boiling point of methane

  • A. 0.427
  • B. 144
  • C. 195.7
  • D. None of the abov
Answer: A — 0.427
Methane has a liquid relative density of approximately 0.427 at its atmospheric boiling point of -161.5°C.

27. The ability of a substance to cause damage to living tissue or impairment of the central nervous system

  • A. Asphyxia
  • B. Frost bit
  • C. Toxicity
  • D. None of the abov
Answer: C — Toxicity
Toxicity is the inherent property of a substance to cause biological damage to living tissue, systemic poisoning, or impairment of the central nervous system.

28. How suction capacity and resulting discharge rate can be regulated

  • A. By reducing pump speed
  • B. By throttling the discharge valv
  • C. By creating bypass (return flow)
  • D. All the abov
Answer: D — All the abov
Centrifugal cargo pump discharge rate can be regulated by varying motor/turbine speed, throttling the discharge valve, or utilizing recirculating bypass lines.

29. What are the necessary condition that must take place for an electrical discharge to occur

  • A. Electrostatic separation
  • B. Electrostatic accumulation
  • C. Electrostatic discharg
  • D. All the abov
Answer: D — All the abov
The correct answer is All the abov. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

30. Gas ships cargo compressor room, cargo tank area are

  • A. Snap back area
  • B. Gas safe area
  • C. Gas dangerous
  • D. All the abov
Answer: C — Gas dangerous
The correct answer is Gas dangerous. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

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