CHEMCO exit exam questions and answers — Set 10
Set 10 of the Advanced Training for Chemical Tanker Cargo Operations (CHEMCO) exit exam bank — 30 of 377 questions, with the correct option marked. This bank is answer-only: the source published no usable explanations for it, so there are none here either. 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 10 — 30 CHEMCO exit exam questions with answers
1. The airborne concentrations of substances (such as hydrogen sulfide) under which nearly all workers may be repeatedly exposed without adverse effects are called
- A. exposure limits
- B. concentration limits
- C. threshold limit values
- D. substance limit values
2. Optimum Oxygen values in the inert gas for delivery into cargo tanks is between:
- A. 1 to 2%
- B. 3 to 4%
- C. 5 to 6%
- D. 9 to 10%
3. If a cargo tank has not been certified as gas free,
- A. breathing apparatus would not be necessary in an emergency as you would only be in the tank a short time
- B. a man may work safely without breathing apparatus in cold weather, as vapors are less volatile
- C. entry without a breathing apparatus may be made at the top of the tank since petroleum vapors are heavier than air
- D. breathing apparatus should always be used
4. Cargo tank pressure is monitored on tankers:
- A. To ensure IG backpressure is slightly positive at all times
- B. To prevent back pressure
- C. To ensure enough tanks are open for loading
- D. To ensure that the loading rate is not too high
5. Identify the statement that highlights the purpose of using a non-catalytic heated filament gas indicator,
- A. The working of catalytic gas indicator depends on the property of its combustion with air.
- B. Since the inerted atmosphere is deficient in oxygen the catalytic gas indicators cannot be used in inerted atmospheres.
- C. Instruments used in inerted atmosphere have a filament sensitive to the variations in the heat conductivity.
- D. Instruments used in inerted atmosphere have a filament that are good for monitoring inerting operations.
6. The highest concentration of a harmful substance to which a person may be exposed without danger to health, is termed the
- A. vapor pressure
- B. tolerance point
- C. threshold limit value
- D. odor threshold
7. Vessel's enclosed spaces that are not to be treated as such:
- A. Spaces which must be entered through small hatchways or access points;
- B. Cargo tanks and holds ;
- C. Double-bottom tanks;
- D. Crew accommodation
8. Which would be the appropriate arrangement for entering into a DB tank through the ductkeel?
- A. Entry permit for ductkeel and standby person at the entrance
- B. Entry permit for DB tank and standby person loacated inside ductkeel outside DB tank
- C. Combined entry permit for both but standby person ductkeel entrance and DB entrance
- D. Separate enclosed space entry permit for both spaces including standby person outside both
9. Which of the devices listed would be safe to use in a compartment with insufficient oxygen?
- A. Wet handkerchief.
- B. Self-contained breathing apparatus.
- C. Dust or gas mask.
- D. Canister type mask.
10. Where is the electrostatic discharge plate installed?
- A. Near the cargo manifold
- B. At the forward end of the ship
- C. At the accommodation entrance on upper deck
- D. At the aft part of the ship
11. For Oxygen analyzer, identify the key principle upon which the analyzer is working,
- A. A Wheatstone bridge circuit is formed using the two wires. It is used to measure a resistance by balancing two legs of the circuit.
- B. The sample of atmosphere is filtered and passed through a diffuser before reaching the two chambers.
- C. One chamber is with a magnetic field and the other without a magnetic field.
- D. A difference in the thermal conductivity of the oxygen with respect to air is developed and this causes an imbalance in the resistance.
12. The ________ depends upon the pressure of contact exerted on live wires.
- A. voltage
- B. current
- C. impedance
- D. power
13. What is related to the relaxation time of the material in which the electical charges are accumulated?
- A. That material's density
- B. That material's viscosity
- C. That material's conductivity
- D. That material's flammabilty
14. Operating Principle of the Infrared instrument: identify the key principle that leads to detection of hydrocarbon gas,
- A. The amount of absorption is related to the concentration of the gas and is measured by a set of optical detectors and suitable electronic systems.
- B. The change in the intensity of the absorbed light is measured relative to the intensity of light at a non-absorbed wavelength.
- C. When there is no gas present the signals of reference signal detector and measurement signal detector are balanced.
- D. When there is combustible gas present, there is a predictable drop in the output from measurement signal detector because the gas is absorbing light.
15. When using a permit to work system one must make how many copies of the permit ?
- A. One copy
- B. Two copies
- C. Three copies
- D. Four copies
16. A method NOT usually allowed for cleaning up oil spills would be the use of _________.
- A. skimmers
- B. dispersants
- C. straw
- D. sawdust
17. A liquid-filled pressure vacuum breaker
- A. is fitted on the tank dome
- B. is fitted on the main deck a tanker
- C. is fitted on the inert gas main line of a tanker
- D. is fitted in the pump room
18. A thermoelectric detector:
- A. Uses a heat sensor uses a fixed temperature stop
- B. converts heat to electrical energy
- C. detects a rise in tempetrature
- D. uses a fixed temperature stop
19. The vacuum strip system was developed on oil tankers to
- A. remove all hydrocarbon gases from the tanks after discharging
- B. prevent cavitation in centrifugal cargo pumps
- C. quickly remove rain water collecting on deck
- D. discharge cargo without any human intervention
20. Gas Dispersion through tank vents; There is a potential danger of fire and explosion if the flammable zone with emitted vapor reaches any location where there may be sources of ignition such as the follows; which one of these can be prevented easily by onboard systems?
- A. Superstructures and accommodation blocks into which the gas can enter through doors, ports or ventilation intakes.
- B. The cargo deck which, although it is usually regarded as free of sources of ignition, is a work area and thoroughfare.
- C. An adjacent jetty which, although it is usually regarded as free of sources of ignition, is a work area and thoroughfare.
- D. Adjacent vessels such as lightering ships, bunker and stores craft, pilot and crew transfer boats.
21. A stripping pump is fitted in the pump room so that
- A. the last remaining traces of liquid can be pumped out from the tanks, pipelines and pumps
- B. cargo from the tanks can be discharged if the main pumps should fail
- C. the liquids collected in the bilge can be pumped out
- D. slops can be discharged overboard at a slow rate
22. Tanks of tankers do not exceed:
- A. 0.1 of ship’s length
- B. 0.15 of ship’s length
- C. 0.2 of ship’s length
- D. 0.25 of ship’s length
23. What do you understand from the term "Bleed off COW" ?
- A. The process of pressure testing the COW lines onboard
- B. The process of diverting part of cargo discharged for reducing rate
- C. The process of diverting part of cargo discharged for crude oil washing
- D. The process of draining oil from the COW lines after washing
24. The pipeline system that has valves fitted on bulkheads is called:
- A. The direct line system
- B. The free flow system
- C. The ring main system
- D. The free line system
25. Before gas freeing operations the hydrocarbon content is reduced to:
- A. to 15% or less by volume
- B. to 10% or less by volume
- C. to 8% or less by volume
- D. to 2% or less by volume
26. Turbidity:
- A. is an optical characteristic that indicates the degree of clarity of a liquid
- B. is a motion characteristic that indicates the degree of clarity of a liquid
- C. is a refractive characteristic that indicates the degree of clarity of a liquid
- D. is a characteristic that indicates the degree of clarity of a liquid
27. Tank bulkheads on a tanker are strengthened using:
- A. Web frames, transverse webs and stringers.
- B. Longitudinals, transverse webs and stringers.
- C. Web frames, transverse webs and gusset plates.
- D. Gusset plates, transverse webs and longitudinals
28. What is LEAST likely to be used to strip a cargo tank?
- A. Centrifugal pump
- B. Eductor
- C. Rotary pump
- D. Reciprocating pump
29. Deep tanks on oil tankers are used normally to carry
- A. nothing at all
- B. additional ballast in bad weather
- C. extra bunkers for long international voyages
- D. more cargo for increasing freight
30. The main purpose of introducing double hull design in tankers was
- A. to offer an extra layer of protection against environmental pollution
- B. to increase the light weight of ship and reduce ballast required
- C. to allow ships to navigate with reduced UKC without worrying about pollution
- D. to increase the cargo carrying capacity of the ship with same dimensions
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