This page contains answers to Seagull CBT CES test about Fuel Oil System, and serve as a database of questions and answers, using which seafarer can prepare to exams for getting certificate of competence, or just to challenge yourself with knowledge in this theme.
Test about Fuel Oil System
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Amount of questions: 71.
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Biodiesel is being proposed as an alternative fuel for use in marine diesel engines. Which one of the options best describes biodiesel that can be used in an unmodified diesel engine?
A blend of petroleum based diesel fuel and less than 20 % bio fuel.
A pure product of hydrocarbon based oil refining.
A pure product from the processing of vegetable crops.
A blend of petroleum based fuel and water.
“Turbulence” is the term used to describe the movement of the charge air in a diesel engine cylinder. Which one of the following options best describes a feature which helps in generating turbulence?
The geometry of air inlet ports and valves.
The combustion chamber volume.
The piston crown material.
The length of the charge air receiver.
Blended fuel is the term applied to those fuels which are normally produced by mixing which two of the following categories of fuel?
Marine residual fuels.
Marine distillate fuel.
Cargo boil off gas.
Combustion of fuel oil can be considered to be an energy conversion process. Which of the following options best describes the conversion?
Chemical to heat energy.
Heat to mechanical energy.
Chemical to mechanical energy.
Heat to chemical energy.
Dual fuel diesel engines which use gas and fuel oil are used on some ships. Select the option which best describes one of the methods of operation of the fuel systems for these engines:
Low pressure gas is used as the main fuel with fuel oil used to ignite it.
High pressure gas is added to the fuel oil and both injected into the cylinder together.
Low pressure gas and fuel oil are injected into the cylinder separately.
High pressure gas is used as fuel when fuel oil is not available.
Dual fuel systems have been developed to allow diesel engines to operate on gas fuel on some ships. How is the gas admitted to the cylinder in these systems? Select all the options that apply:
Admitted through the air inlet.
Admitted directly to the cylinder through the same injection valve as the fuel oil.
Admitted directly to the cylinder through a separate injection valve to the fuel oil.
Admitted via the turbocharger.
From the options given select all of those which make up the fire triangle:
Chemical or Chain Reaction.
Fuel oil viscosity control is considered necessary for diesel engines operating on heavy fuel oil. Which one of the following best describes the principle of operation of a Viscotherm unit?
Measurement of differential pressure in a capillary tube.
Measurement of outlet pressure of the unit pump.
Measurement of differential pressure between inlet and outlet to the unit.
Measurement of the differential temperature across the unit.
Fuels are sometimes blended onboard the ship prior to use. Which one of the following best describes why this process carried out?
To control the fuel viscosity at the engine inlet.
To control the temperature at the engine exhaust.
To control the density at the purifier inlet.
To control the temperature at the engine inlet.
How is the fuel normally ignited during the start-up of a ship’s boiler?
Using a spark igniter.
Using the hot furnace air.
Using an external flame.
Using hot furnace brickwork.
In fuel combustion what is meant by the term “stoichiometric mixture”?
A fuel air mixture, which has the ideal minimum amount of air required for complete combustion of the fuel.
A fuel air mixture, which has less than the ideal minimum amount of air, required for complete combustion of the fuel.
A fuel air mixture, which has more than the ideal minimum amount of air, required for complete combustion of the fuel.
A fuel air mixture that will not burn.
Many boiler burner units include an air register. What is the purpose of an air register?
It controls the quantity of combustion air entering the furnace.
It controls the direction and movement of the combustion air entering the furnace.
It measures the quantity of combustion air entering the furnace.
It prevents backflow of exhaust gas from the furnace.
Many diesel engine high pressure fuel pumps have plungers with helical profiles cut into them. How do these helical profile type plungers control the timing and quantity of fuel delivered to the cylinder?
The trailing edge controls both the start and end of injection.
The leading edge controls both the start and end of injection.
The trailing edge controls the start of injection and the leading edge controls the end of injection.
The leading edge controls the start of injection and the trailing edge controls the end of injection.
Most boiler burner units feature a swirl plate and a diffuser. What is the purpose of these two components?
To drive the rotary cup part of the burner unit.
To control the amount of air entering the furnace.
To control the fuel movement and promote mixing with the combustion air.
To control the combustion air movement and promote mixing with the fuel.
On large diesel engines it is common practice to use individual high pressure pumps positioned at each cylinder unit. Which one of the following gives the reason for doing this?
To reduce the size of the pump units.
To make the pump adjustment easier.
To allow a long camshaft to be used.
To keep the high pressure fuel pipes as short as possible.
Select the correct option from those given to complete the statement. The fuel standard commonly used for the specification of marine fuels is:
MARPOL (Annex I).
Some boiler burner units have steam passing through them during operation. What is the main purpose of using steam in a boiler burner unit?
To keep the fuel hot.
To improve fuel atomisation.
To keep the burner part clean.
To heat up the combustion air.
Some boiler use rotary cup burners instead of jet nozzle types. Which one of the following options best describes how rotary cup burners differ from jet nozzle types?
Rotary cup burners rely on electrostatic charge for atomisation of the fuel atomization of the fuel.
Rotary cup burners operate on much lower fuel pressures than simple jet nozzle types.
Rotary cup burners normally use steam atomisation.
Rotary cup burners operate with simple on/off control.
Some diesel engine fuel injectors are designed to re-circulate the fuel when not actually injecting it. Why is recirculation desirable? Select all of the options which are correct:
It allows the engine to be stopped on heavy fuel oil.
It helps to remove residual heat from the injection.
It means that separate fuel valve cooling is not required.
It helps to maintain correct fuel viscosity.
Some diesel engine manufacturers have introduced the use of fuel and water emulsion as part of their exhaust emission control measures. How do these emulsions help to reduce air pollutants in exhaust gas emissions?
They lower the maximum cylinder temperature and reduce NOx levels.
The water washes out sulphur and reduces SOx levels.
They dissolve the ash components of the fuel and reduce particulate levels.
The oxygen in the water improves combustion of carbon and reduces carbon monoxide levels.
Some diesel engines feature a twin injection system designed to improve fuel injection performance. Select the option, which best describes this feature:
A constant amount of fuel is injected by the first injector at all loads, while the amount through the second one varies.
An equal amount of fuel passes through each injector in sequence.
An equal amount of fuel passes through each injector simultaneously.
A variable amount of fuel is injected by the first injector, while the amount through the second one is constant at all loads.
Some diesel engines have fuel injection systems, which incorporate pilot injection. What is the main purpose of using pilot injection?
To reduce ignition delay.
To increase ignition delay.
To increase maximum cylinder pressure.
To reduce maximum cylinder pressure.
Some diesel engines operate on a fuel mixture, which is blended onboard. Which one of the following is a means to control the makeup of the blended fuel?
Preset viscosity, temperature and blend component ratio.
Preset temperature and blend component ratio and varying viscosity.
Preset viscosity and temperature with varying pump pressure.
Preset viscosity and temperature with varying ratio of blend components.
Some diesel engines operate with pilot injection as a feature of the fuel injection system. How is pilot injection usually achieved?
By having two injectors injecting fuel at the same time.
By having two fuel cam profiles.
By having two fuel injection pumps.
By having two injection periods with a single injector.
Some high pressure pumps used in diesel engine fuel injection systems control the timing and quantity with a valve arrangement rather than a helix cut into the plunger. How is control of the pumps usually achieved using valves?
Spill valve to control the start and end of injection.
Suction valve to control the start and end of injection.
Spill valve to control start of injection and suction valve to control the end.
Suction valve to control start of injection and spill valve to control the end.
Some machines use fuel directly to provide the energy required for operation. Which of the following machines would you include in this group?
The complete combustion of carbon should produce which of the given options?
Carbon dioxide and heat.
Carbon monoxide and heat.
Carbon dioxide, water vapor and heat.
NOx and SOx components in the exhaust gas emissions.
The peak pressure allowed in a diesel engine cylinder is limited to a maximum value during the engine design stage. What determines this limit?
The strength of the combustion chamber components.
The amount of fuel that can be injected into the cylinder.
The amount of charge air that can be admitted to the cylinder.
The cylinder compression pressure.
The term jerk pump is often used when describing the type of high pressure fuel pump used in diesel engine fuel injection systems. Which one of the following options best defines this type of pump?
A cam actuated pump, which has a rapid movement.
A crank actuated pump, delivering to a common manifold.
A distributor type pump, driven from the camshaft.
A positive displacement pump.
The term “atomisation” is often used in relation to diesel engine fuel injection. Which of the following options best defines the term “atomisation”?
The breakup of a liquid fuel stream into fine droplets.
The formation of a combustible fuel air mixture.
The mixing of fuel and air in a diesel engine cylinder.
The distribution of fuel in a diesel engine cylinder.
The vessel you are sailing on, which has one settling tank and one service tank in the fuel system, is due operate in a SECA. When would you need to start to change over to low sulphur fuel if you are currently operating on normal heavy fuel?
At the time before entry into the SECA stated in the ship’s fuel changeover procedure.
Just as you enter the SECA.
In time to consume the contents of the in service system.
In time to consume the contents of the service tank and the in service system.
Under MARPOL Annex VI legislation which one of the following best describes the difference between operating an engine inside a SECA compared to one outside a SECA?
Fuel with a lower sulphur content must normally be used in a SECA.
Fuel with a higher sulphur content must normally be used in a SECA.
Fuel with a lower nitrogen content must normally be used in a SECA.
Fuel with a lower viscosity must normally be used in a SECA.
Variable injection timing (VIT) is sometimes used in the control of a diesel engine fuel injection system. How is a high pressure fuel pump using valve control arranged to provide VIT?
The governor output is used to control only the suction valve.
The governor output is used to control both suction and spill valve.
The governor output is used to control only the spill valve.
The governor output is used to control only the delivery valve.
Water/fuel emulsions are used in some diesel engines as a means of reducing the level of NOx emissions. What is a possible side effect of using these emulsions?
Emulsions normally result in lower specific fuel consumption.
Emulsions will give some secondary atomisation of heavy fuel improving combustion efficiency.
Emulsions normally assist in lubricating the cylinder liner.
Emulsions normally reduce SOx levels.
What are the products from the complete combustion of hydrogen?
Carbon dioxide and heat.
Water vapor and heat.
What is meant by the term common rail system when applied to a diesel engine fuel injection system?
A system in which the high pressure pumps are supplied from a common suction manifold.
A system in which the high pressure pumps deliver into a manifold supplying all of the fuel injectors.
A system in which a multi cylinder fuel pump block is used.
A system where all of the fuel pumps are controlled by a single fuel rack.
What is meant by the term direct injection in relation to diesel engine fuel injection systems?
A system in which fuel is injected into a pre-combustion chamber.
A system in which fuel is injected into the combustion chamber.
A system in which fuel is admitted with the inlet air.
A system in which fuel is taken straight from the settling tanks to the engine.
What is the most common method used to allow the position of fuel cams to be individually adjusted on the camshaft?
The majority of fuel cams are mounted on hydraulic sleeve couplings.
The majority of fuel cams are mounted on splines.
The majority of fuel cams are bolted to flanges.
The majority of fuel cams are of split design.
What is the normal source of ignition in most diesel engines?
Heat from the compressed air charge in the cylinder.
Heat from the fuel.
Heat from a glow plug.
A spark igniter.
When diesel engines are operated on heavy fuel oil, the fuel is heated up to achieve the correct injection viscosity. How is the fuel system prevented from gassing up when operating this way?
By maintaining a high enough pressure in the low pressure system to prevent vapor formation.
By increasing the viscosity control setting to limit the fuel temperature.
By setting a temperature limit of below 100 °C.
By operating the system with an open vent.
When would an oil fired inert gas generator normally be fitted onboard an oil tanker?
When the vessel has no steam boiler.
When the vessel has a steam propulsion plant.
When the vessel has diesel propulsion and an auxiliary steam plant.
When the vessel has steam turbine driven generators.
Which marine legislation has led to the introduction of low sulphur fuels in the shipping industry?
MARPOL (Annex VI).
The ISM Code.
MARPOL (Annex I).
Which of the following are commonly used as fuels onboard commercial ships? Select all the correct options:
Marine diesel oil.
Boil off gas from LNG cargoes.
Marine residual fuel.
Which of the following components in a diesel engine high pressure fuel injection system contribute to the control of the quantity and timing of the fuel delivery to the engine? Select all applicable options:
High pressure fuel pump.
Fuel pump cam.
Which of the following fuel components will release the most energy, measured in MJ/kg, during the combustion of marine residual fuel?
Which of the following machines would be described as an internal combustion engine?
A diesel engine.
A steam turbine.
An air compressor.
A steam boiler.
Which of the following options best describes the term “self ignition temperature”?
The minimum temperature at which a combustible mixture of fuel vapor and air will ignite without an external ignition source.
The minimum temperature at which a combustible mixture of fuel vapor and air can be ignited with an external ignition source.
Another term for the flash point of a fuel.
The minimum temperature at which combustion will continue when the source of ignition is removed.
Which one of the following best describes the purpose of the spring in a fuel injection valve?
To allow adjustment of the valve closing period.
To give positive seating of the valve to prevent back flow of gas from the cylinder into the fuel system.
To limit the lift of the valve needle.
To allow recirculation of fuel through the valve.
Which one of the following best describes why a low pressure alarm is often fitted in the low pressure part of a diesel engine heavy fuel oil system?
To indicate when distillate fuel has reached the pump supply manifold.
To minimize the risk of engine fuel starvation.
To indicate when the level in the fuel oil service tank is low.
To indicate when the service tank is not fully open.
Which one of the following best explains why high pressure fuel pipes fitted to many diesel engines are often double skinned?
So that any leakage is contained.
So that if the inner skin fails operation can continue using the outer skin.
To prevent heat loss by insulating the inner skin.
To prevent engine room personnel from contacting the hot inner skin.
Which one of the following boiler operating parameters would normally give automatic shut-down of the boiler in event of alarm condition?
Exhaust high oxygen level.
High fuel temperature.
High steam temperature.
Which one of the following elements of diesel engine exhaust emissions are considered as atmospheric pollutants?
Which one of the following features would you expect to find with an inline multi cylinder fuel pump block arrangement?
Positioning on the engine at crankshaft.
High pressure fuel pipes without bends.
A separate camshaft for each cylinder.
A single rack to control all of the fuel pumps simultaneously.
Which one of the following gases would you normally associate with the combustion of hydrocarbon fuel containing sulphur in a diesel engine?
Sulphur oxide, SO.
Hydrogen sulphide, H2S.
Sulphur carbide, SC3.
Sulphur dioxide, SO2.
Which one of the following options best describes a “stoichiometric mixture”?
A mixture of fuel and air that will ignite.
A mixture of fuel and air containing approximately 30 % excess air.
A mixture of fuel and air containing approximately 5 % excess air.
A mixture of fuel and air containing the exact theoretical amount of air for complete combustion of the fuel.
Which one of the following options best describes how combustion in a boiler furnace is different to that in a diesel engine cylinder?
Boiler combustion is controlled by measuring the exhaust temperature.
Boiler combustion is started from cold using distillate fuel.
Boiler combustion requires more excess air.
Boiler combustion is a continuous process.
Which one of the following options best describes the gas used as a source of fuel on some LNG carriers?
It is a low pressure liquid, after processing by the reliquefaction plant.
It is a high pressure liquid, and stored in bunker tanks within the cargo area.
It is a high pressure liquid, having been pumped from the cargo tanks.
It is a low pressure gas, having evaporated from the cargo tanks.
Which one of the following options best describes when you would normally expect to find a thermal oil heating unit fitted onboard a ship?
When there is only one steam boiler.
When the ship has steam propulsion.
When the ship only has 4 stroke diesel engines.
When the ship operators on heavy fuel, but has no steam boiler.
Which one of the following options best describes why incinerators need a fuel oil system?
To establish a flame prior to burning waste oil.
To inject fuel into the sludge before they are pumped to the furnace.
To soak solid waste material before burning.
To allow the incinerator to be operated when there is no waste oil, sludge or waste material.
Which one of the following options best describes why recirculation type fuel injectors are sometimes fitted to diesel engines?
They allow the engine to be run on heavy fuel oil.
A separate fuel valve cooling system is not required.
Removes the need for the vessel to carry distillate fuel.
Removes the need to have viscosity control.
Which one of the following options is a requirement of a diesel engine fuel injection pump?
Ensure the correct quantity of air admitted.
Ensure the correct quantity of fuel injected.
Ensure the fuel at the right temperature to ensure combustion.
Ensure the fuel is at the viscosity to ensure combustion.
Which one of the following options is an acceptable method of checking the timing of diesel engine high pressure fuel pumps?
Spill cut off method.
Matching witness marks on pump casing and camshaft cover.
Measuring fuel pump discharge pressure.
Testing fuel injector lift pressure.
Which one of the following options is considered to be a product of incomplete combustion of fuel in a diesel engine cylinder?
Which one of the following options is the best definition of the “flash point” of a fuel?
The temperature, at which a fuel gives off vapors which can be ignited by an external ignition source.
The temperature, at which a fuel will spontaneously ignite.
The temperature, at which the fuel changes state from liquid to gas.
The temperature, at which fuel will continue to burn once ignited.
Which one of the following problems is likely to occur if the correct procedure for changing over from heavy fuel to distillate fuel prior to stopping a diesel engine is not followed?
Gassing up due to distillate fuel component overheating.
SECA limits may not be met.
Viscosity control may remain in manual mode.
The engine may not stop.
Which one of the following problems is most often associated with blended marine fuels?
Low flash point.
Which one of the following statements is true?
Marine diesel oil is a mixture of distillate and a small amount of residual or heavy fuel.
Marine diesel oil is a mixture of distillate and a large amount of residual or heavy fuel.
Marine diesel oil is a residual fuel.
Marine diesel oil is a pure distillate fuel.
Which parameters of a diesel engine fuel system are normally covered by alarm monitoring? Select all of the correct options:
Which part of a diesel engine fuel cam profile is normally used to control the rate of fuel delivery?
The controlled speed section.
The base circle section.
The cam peak section.
The acceleration and deceleration sections.
Why is the exhaust from an oil fired boiler a suitable source of inert gas to use to inert cargo tanks on an oil tanker?
The boiler exhaust normally contains less than 5 % oxygen.
The boiler exhaust normally contains no oxygen.
The boiler exhaust normally contains about 30 % oxygen.
The boiler exhaust gas is normally clean and contaminant free.
Why is variable injection timing (VIT) incorporated in some diesel engine fuel systems?
To increase thermal efficiency and reduce specific fuel consumption.
To reduce the maximum cylinder pressure.
To increase the minimum compression pressure.
To increase the maximum load of the engine.
Test about Fuel Oil System