Test about Inert Gas Generator

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Правильні відповіді:
1

A water column type pressure vacuum breaker device may be fitted to the deck main of an inert gas system. Which of the statements given in the options is true?

Правильну відповідь:

This type of device is usually designed to operate before the deck water seal reaches it’s limit.

Ваша відповідь:

This type of device is usually designed to operate only after the deck water seal fails.
2

An independent inert gas generator is supplying the inert gas during cargo discharge operations when the low pressure alarm sounds. Which one of the giving options is most likely to automatically happen when such a condition develops?

Ваша відповідь правильна:

Automatic shutdown of the cargo pumps.
3

Complete the following statement to give the IMO definition of an inert condition for a cargo tank. A condition in which the oxygen content throughout the atmosphere of a tank has been:

Ваша відповідь правильна:

Reduced to 8 % or less by volume by addition of inert gas.
4

Considering an oil tanker fitted with an independent inert gas generator system. Which of the items identified in the options is most likely to be operating continuously when the cargo tanks are full of cargo?

Ваша відповідь правильна:

Deck seal pump.
5

Considering the ullage space of a cargo tank containing petroleum based oil. Which of the given statements best describes the atmosphere of the ullage space?

Ваша відповідь правильна:

It will contain a mixture of atmospheric air and hydrocarbon gases with an oxygen content of less than 21 % by volume.
6

During loaded passage the inert gas pressure in the cargo tanks can vary due to changes in ambient temperature. Which of the given options would be the preferred way to maintain the correct pressure on a vessel fitted with an independent inert gas generator?

Ваша відповідь правильна:

Intermittent operation of the generator in automatic mode to top up the pressure.
7

During start-up sequence of an independent inert gas generator it is necessary to allow time for a pre-purge of the furnace whether in manual or automatic mode. What is the recommended minimum time for such a pre-purge operation?

Ваша відповідь правильна:

3 minutes.
8

During the operation of an independent inert gas generator, a problem develops with the scrubber unit effluent valves such that the water level in the scrubber unit reaches alarm condition. In addition to the alarm sounding what other action is most likely to result from this condition?

Ваша відповідь правильна:

Immediate shutdown of the inert gas generator system.
9

During the start-up procedure for an independent inert gas generator when should the inert gas deck main valve be opened?

Ваша відповідь правильна:

Once the measured oxygen content reaches the set point value.
10

For an independent inert gas generator with automatic control which one of the parameters in the given options is most likely to have a controller set point that can be adjusted by the operator?

Ваша відповідь правильна:

The pressure of the inert gas in the deck main.
11

For an independent inert gas generator with automatic control which one of the parameters in the given options is most likely to have a set point that can be adjusted by the operator?

Ваша відповідь правильна:

The oxygen content of the inert gas.
12

For the independent inert gas generator considered in this module how is the oxygen content of the inert gas automatically controlled?

Ваша відповідь правильна:

By adjustment of the fuel capacity control setting.
13

For the independent inert gas generator considered in this module how is the primary control of the deck main pressure at its set point achieved?

Ваша відповідь правильна:

By the automatic operation of the atmospheric vent valve.
14

Guidance regarding the IMO requirements for inert gas systems is given in the IMO publication Inert Gas Systems, 1990 edition. Which other publication from IMO gives general guidance relating to inert gas systems?

Ваша відповідь правильна:

SOLAS.
15

High efficiency burners are often used in independent inert gas generators to ensure good combustion and that high quality inert gas is produced. Monitoring the gases from the combustion process can give an indication of the efficiency of the combustion. Which of the given indicates good combustion?

Ваша відповідь правильна:

Minimum carbon monoxide content.
16

How is the humidity of the inert gas supply controlled for independent inert gas generator systems fitted to gas and chemical carriers?

Ваша відповідь правильна:

By cooling and then drying the gas before the inlet to the deck main.
17

How is the quantity of inert gas from an independent inert gas generator normally monitored?

Ваша відповідь правильна:

By the pressure in the deck main.
18

In auto start mode which of the given options will start first when starting up an independent inert gas generator? Assume all normal pre-start requirements have been met:

Ваша відповідь правильна:

Scrubber pump.
19

In the event of a multiple alarm condition occurring during operation of an independent inert gas generator what will be the normal arrangement for the alarm display?

Ваша відповідь правильна:

All alarms will be listed in order of priority.
20

In the event of an alarm condition occurring during operation of an independent inert gas generator how will the operator know which parameter is in alarm condition? Select the most common method from the options given:

Ваша відповідь правильна:

The audible alarm will sound and the alarm status screen will automatically display.
21

In the event that the oxygen content of the inert gas supply from an inert gas generator exceeded the value of the set point an alarm would sound. Which one of the given options is also the most likely to occur in such a situation?

Ваша відповідь правильна:

The automatic vent valve would open and the deck main valve would close.
22

Independent inert gas generator systems fitted to gas carriers often have refrigerated type cooler dryer units fitted to control the humidity of the inert gas. Which condition of the gas is used to control entry of the gas into the drier section of such a unit?

Ваша відповідь правильна:

The temperature of the inert gas.
23

Independent, oil fired, inert gas generators are usually operated on distillate fuel rather than residual fuel. What is the main reason for this?

Ваша відповідь правильна:

Operating on distillate fuel normally produces a cleaner exhaust gas with a lower oxygen content due to relatively good combustion.
24

On which one of the vessel types given in the options would a nitrogen generator most likely to be fitted for the purpose of providing inert gas to the cargo system and associated spaces?

Ваша відповідь правильна:

Chemical tanker.
25

One of the main reasons for the introduction of inert gas systems onboard oil tankers was the increase in the number of explosions onboard these vessels. Which one of the given options was found to be the main ignition source for these explosions?

Ваша відповідь правильна:

Build-up of static electricity during cargo and tank cleaning operations.
26

SOLAS stimulates the maximum content of oxygen by volume that an inert gas system, including an independent inert gas generator type, must be capable of supplying. Which of the given options is this maximum value?

Ваша відповідь правильна:

5 %.
27

Select the best option from those given to complete the following statement in relation to pressure vacuum breakers as fitted to the distribution system of some independent inert gas generator systems. The correct operation of a liquid column type pressure vacuum breaker is dependent on:

Ваша відповідь правильна:

The correct specific gravity of the liquid and the liquid column height.
28

Some oil fired, independent inert gas generators incorporate capacity control to regulate the rate of delivery of the inert gas to the distribution system. Which of the given options is the primary element regulated by such a control feature?

Ваша відповідь правильна:

The combustion air blower load.
29

The combustion air blowers of an inert gas generator may be used to supply fresh air during venting and gas freeing operations following purging of cargo tanks and lines. What precautions must be taken when carrying out such operations with an independent inert gas generator?

Ваша відповідь правильна:

Ensure all none purged tanks are properly isolated from the inert gas main.
30

There are a number of different types of inert gas system in use onboard oil tankers including the so called flue gas system. What does the term flue gas normally refer to in the context of inert gas systems?

Ваша відповідь правильна:

Boiler exhaust gas.
31

What effect on the upper and lower flammable limits does the introduction of inert gas into a cargo oil tank have?

Ваша відповідь правильна:

It reduces the upper flammable limit and increases the lower flammable limit.
32

What is generally taken as the minimum amount of oxygen in a mixture of atmospheric air and hydrocarbon gases that gives a safe margin against the risk of combustion?

Ваша відповідь правильна:

8 %.
33

What is the SOLAS requirement regarding non-return devices in the inert gas main for inert gas systems on oil tankers?

Ваша відповідь правильна:

There must be at least two devices one of which should be a water seal type.
34

What is the approximate minimum amount of oxygen in a mixture of atmospheric air and hydrocarbon gases that will support combustion?

Ваша відповідь правильна:

11 %.
35

What is the main reason for controlling the humidity of the inert gas produced by an independent inert gas generator when fitted to a gas or chemical tanker?

Ваша відповідь правильна:

To avoid compatibility problems with the cargo.
36

What is the main risk associated with dilution of a normally inerted cargo oil tank atmosphere with fresh air?

Ваша відповідь правильна:

During the process the atmosphere may be within the explosive range for some of the time.
37

What is the percentage content by volume of oxygen in atmospheric air generally taken to be?

Ваша відповідь правильна:

21 %.
38

What is the recommended interval for checking the calibration of an oxygen analyser as fitted to an independent inert gas generator system?

Ваша відповідь правильна:

At least every 8 hours when the system is in use.
39

When considering an independent, oil fired inert gas generator how is it normally protected in the event of a flame failure of the main burner?

Ваша відповідь правильна:

It will normally result in audible and visual alarms and an automatic shutdown of the generator.
40

When considering an independent, oil fired inert gas generator how is the furnace usually prevented from overheating?

Ваша відповідь правильна:

By surrounding the furnace with a water jacket.
41

When considering an independent, oil fired inert gas generator how is the required flow of inert gas normally generated?

Ваша відповідь правильна:

The combustion air fans provide sufficient pressure to ensure the necessary inert gas flow.
42

When considering an independent, oil fired inert gas generator suitable for service onboard an oil tanker what are the SOLAS requirements for the oxygen content of the inert gas supply?

Ваша відповідь правильна:

A maximum of 5 %.
43

When considering an independent, oil fired inert gas generator suitable for service onboard an oil tanker what is the SOLAS requirement regarding the composition of the tank atmosphere to be maintained?

Ваша відповідь правильна:

A maximum of 8 % oxygen content.
44

When considering an independent, oil fired inert gas generator what is the main purpose of the pilot burner?

Правильну відповідь:

It is used to provide an ignition source for the main burner.

Ваша відповідь:

It is used to preheat the combustion air to make it easier to ignite the main burner.
45

When considering an independent, oil fired inert gas generator which incorporates a sea water scrubber unit. How is the water content of the inert gas normally kept to a minimum if the generator is used onboard an oil tanker?

Ваша відповідь правильна:

A demister unit is fitted before the scrubber inert gas outlet.
46

When considering an independent, oil fired inert gas generator, other than providing a vent to the atmosphere during start-up of the plant, what is the other main purpose of the automatic atmospheric vent valve?

Ваша відповідь правильна:

It is used in conjunction with the inert gas main valve to regulate the pressure in the inert gas main.
47

When considering the automatic operation of an independent inert gas generator the start-up sequence normally has delays built in to ensure correct timing of the sequence. For example, there will be a delay in the sequence to ensure sufficient furnace purging time. How can these delays be ensured in manual mode?

Ваша відповідь правильна:

By the use of timed interlocks which operate even in the manual mode.
48

When considering the water supply to the deck water seal for an inert gas system which of the following statements is true?

Ваша відповідь правильна:

There should be at least one independent pump for continuously supplying water to the deck seal.
49

When gas freeing a normally inerted cargo oil tank what should be the first step in the operation?

Ваша відповідь правильна:

Purge with inert gas to bring the atmosphere to below the critical dilution line.
50

Where a liquid column type pressure vacuum breaker device is fitted to the deck main of an inert gas system which liquid is normally used to fill the device?

Ваша відповідь правильна:

A water glycol mix.
51

Where in an independent inert gas generator system as fitted onboard a gas carrier would you expect to find a desiccant dryer unit?

Ваша відповідь правильна:

As part of the humidity control system.
52

Which is the best test gas to use when checking and adjusting the zero setting of an oxygen analyser as fitted to an independent inert gas generator system?

Ваша відповідь правильна:

Nitrogen.
53

Which of the control touch screens considered in this module will allow the operator single button control of the start-up of the inert gas system if all pre-start conditions are met?

Ваша відповідь правильна:

Auto-start screen.
54

Which of the given options describes the lower explosive limit in relation to the atmosphere of a cargo oil tank atmosphere?

Ваша відповідь правильна:

The least proportion of hydrocarbon gases in a mixture with atmospheric air which is flammable.
55

Which of the given options describes the upper explosive limit in relation to the atmosphere of a cargo oil tank atmosphere?

Ваша відповідь правильна:

The highest proportion of hydrocarbon gases in a mixture with atmospheric air which is flammable.
56

Which of the given options is the main reason for ensuring that the air cone of the burner unit for an independent inert gas generator is properly positioned and maintained?

Ваша відповідь правильна:

If not, it will result in poor combustion.
57

Which of the given options is the one that will most influence the combustion efficiency for the burner type described in this module?

Ваша відповідь правильна:

Distance from the main burner tip to the edge of the air cone.
58

Which of the given options represents the approximate percentage content by volume of nitrogen in atmospheric air?

Ваша відповідь правильна:

79 %.
59

Which of the given ranges of oxygen content by volume is likely to be achieved when supplying inert gas from an independent inert gas generator operation on distillate fuel?

Ваша відповідь правильна:

0,5 % to 3 %.
60

Which of the given statements best describes the operation of gas freeing when considering oil tankers fitted with inert gas systems?

Ваша відповідь правильна:

The introduction of fresh air into a tank to remove all toxic, flammable and inert gases and increase the oxygen content to 21 %.
61

Which of the statements given in the options best describes the SOLAS requirements for inert gas systems fitted to a gas carrier?

Ваша відповідь правильна:

There must be two non-return devices fitted in the inert gas deck main.
62

Which one of the alarm conditions given in the options would result in shutdown of the burner unit and the blower continuing to run for a cooling down period when considering the operation of an independent inert gas generator?

Ваша відповідь правильна:

Scrubber pump low discharge pressure.
63

Which one of the given options is the most likely type of fixed gas measuring device to be fitted for monitoring and control of the quality of the inert gas produced by an independent inert gas generator?

Ваша відповідь правильна:

A paramagnetic type oxygen analyser.
64

Which one of the statements given in the options is the most accurate in respect of control of oil fired, independent inert gas generators?

Ваша відповідь правильна:

The generators are usually automatically controlled but normally also have a manual control facility.
65

Which one of the vessel types given in the options is most likely to be fitted with an independent inert gas generator?

Ваша відповідь правильна:

A motor ship designed to carry petroleum product cargoes.
66

Which parameter is normally used as the main indicator of the quality of inert gas supply for the cargo system of an oil tanker?

Ваша відповідь правильна:

Oxygen content.
67

Which term is used to identify the operation whereby fresh air is introduced into a cargo tank in order to remove toxic, flammable and inert gases and to increase the oxygen content of the tank to 21 % by volume?

Ваша відповідь правильна:

Gas freeing.
68

Which term is used to identify the operation whereby inert gas is introduced into a cargo tank in order to reduce the oxygen content throughout the atmosphere of the tank to 8 % or less by volume?

Ваша відповідь правильна:

Inerting.
69

While operating an independent inert gas generator during cargo discharge it is noted that the automatic vent valve is continuously 50 % open. Which of the given options would be the best adjustment to make in order to minimize the gas being lost to atmosphere whilst maintaining the inert gas main pressure?

Ваша відповідь правильна:

Reduce the system capacity control setting.
70

With reference to the adjustment of the set points for the process controllers and the alarm for an independent inert gas generator which one of the statements given in the options is the most accurate?

Ваша відповідь правильна:

There is usually some in build security feature to limit access to these settings.
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