Тест по Gas Measurement (CES v5.0)
Результаты прохождения теста
Ваш результат: 98%
Правильные ответы:
1
A sampling pump for an oxygen analyser with a capacity of 100 ml per stroke, connected to a 10 metre sampling line with a capacity of 25 ml per metre is being used to obtain a sample of a cargo tanks atmosphere. How many strokes of the pump are required to ensure, that a truly representative sample is obtained in practice?
Ваш ответ правильный:
4.2
According to the ISGOTT definition, what is a toxic gas?
Ваш ответ правильный:
A gas, which is harmful to human life.3
For a correctly inerted cargo tank, what would be the expected oxygen content reading, obtained during checks with a portable oxygen analyser?
Ваш ответ правильный:
8 % or less by volume.4
From the options given select the one, that is generally accepted as the minimum oxygen content to support combustion:
Ваш ответ правильный:
11 %.5
From the options given select the one, which is the best approximation of the make-up of normal atmospheric air:
Ваш ответ правильный:
21 % oxygen and 79 % nitrogen.6
How is a time weighted average reading, obtained from a diffusion type detector tube, that has been used over a working period of eight hours?
Ваш ответ правильный:
Divide the total reading on the tube by 8.7
How is the correct volume of the sample controlled when using short term gas detector tubes with a manually operated hand pump?
Ваш ответ правильный:
By using the indicated number of complete pump strokes for that particular tube.8
How would gas detector tubes normally be used to simultaneously check for the presence and concentration of more, than one toxic gas?
Ваш ответ правильный:
Use a single sample pump with a preselected tube set in a multiple tube holder.9
If the oxygen content in an enclosed space falls below 21 % during entry by personnel, what action should be taken?
Ваш ответ правильный:
Stop working and leave the space immediately.10
If the oxygen content of an enclosed space is less than 20 %, under what conditions should entry be made by personnel?
Ваш ответ правильный:
In an emergency only, using suitable breathing equipment.11
It is generally recommended, that non-metallic sampling lines and sensors are used, when obtaining gas samples from cargo tanks. What additional precautions are required, when taking samples during inerting of a cargo tank?
Ваш ответ правильный:
The inerting operation should be stopped for, at least, 30 minutes before introducing sampling equipment into the tank.12
Many of the oxygen analysers used on board ship use paramagnetic type sensors. What is meant by the term “Paramagnetic”?
Ваш ответ правильный:
That a material is temporarily magnetized when exposed to a magnetic field.13
Metal oxide semiconductor type sensors are increasingly being used in personal gas monitors. What is the operating principle of this type of sensor?
Ваш ответ правильный:
Change of electrical resistance as oxide adsorbs the target gas.14
Threshold limit values for exposure to toxic gases are often given as guidance to ensure safety of personnel working, where the gases may be present. Which of the threshold limits given in the options would normally have the highest numerical value?
Ваш ответ правильный:
TLV-C.15
What are the minimum checks, that should be carried out before a gas detecting instrument is used to check the contents of an enclosed space? Select all correct options:
Ваш ответ правильный:
Check for general condition.; Check battery condition.; Check calibration.; Check condition of sample pump and lines and any filters.16
What are the two main reasons for measuring the oxygen content of an enclosed space on board a ship?
Ваш ответ правильный:
To ensure the oxygen content is sufficient to allow safe entry.; To check, if the oxygen content is low enough to avoid flammable mixtures.17
What facility is normally provided for making a zero adjustment to a paramagnetic oxygen analyser?
Ваш ответ правильный:
Alter relative position of optical system.18
What is meant by the term “bump test” in relation to gas detecting instruments?
Ваш ответ правильный:
Checking the reading of the instrument against a known concentration of test gas.19
What is the effect on the oxygen content of the atmosphere of an enclosed space, if hydrocarbon gases are present?
Ваш ответ правильный:
Oxygen content is reduced.20
What is the generally accepted oxygen requirement necessary before safe entry into an enclosed space on board ship?
Ваш ответ правильный:
21 % by volume.21
What is the main advantage of using a personal gas monitor, rather than a long term gas detector tube when working in a potentially hazardous space?
Ваш ответ правильный:
The personal monitor will give an alarm if the exposure limits are exceeded.22
What is the most likely reason for the presence of high levels of NOx and SOx gases in the atmosphere of a cargo tank on an oil tanker?
Ваш ответ правильный:
Inert gas from the combustion of fuel oil has been used to inert the tank.23
What is the normally accepted value for the lower explosive limit (LEL) for hydrocarbon gas in a cargo tank?
Ваш ответ правильный:
1 % by volume.24
What is the normally accepted value for the maximum oxygen content in an inerted cargo tank?
Ваш ответ правильный:
8 % by volume.25
What is the normally accepted value for the upper explosive limit (UEL) for the hydrocarbon gas in a cargo tank?
Ваш ответ правильный:
10 % by volume.26
What is the purpose of gas freeing a cargo tank?
Ваш ответ правильный:
To replace the contents with fresh air.27
What is the time period, that is normally used when stating threshold limit values for the short term exposure limit (TLV-STEL) for toxic gases?
Ваш ответ правильный:
15 minutes.28
What is the time period, that is normally used when stating threshold limit values for the time weighted average for exposure (TLV-TWA) for toxic gases?
Ваш ответ правильный:
8 hours.29
What might indicate, that a galvanic cell type oxygen measuring instrument requires a replacement sensor cell?
Ваш ответ правильный:
Unstable readings during calibration.30
What precautions should be taken prior to use when using an oxygen analyser, that has automatic calibration?
Ваш ответ правильный:
The analyser should be switched on in fresh air.31
What reading will be obtained if a explosimeter, with a range of 0-100 % (LEL), is used to check the hydrocarbon gas content in an atmosphere containing a concentration of hydrocarbon gas, which is three times the LEL:
Ваш ответ правильный:
The meter needle will move to full scale deflection and then fall close to zero.32
What should be considered the main advantage of using a personal gas monitor when working in a space, where the presence of a toxic gas is a potential hazard?
Ваш ответ правильный:
It gives continuous monitoring at the location of the work activity.33
What should be used for the span adjustment of a galvanic cell type oxygen analyser, which is to be used for checking low concentrations of oxygen?
Ваш ответ правильный:
A test gas with 2 % oxygen and 98 % nitrogen.34
What should be used when checking the span during calibration of a combustible gas or hydrocarbon gas detector?
Ваш ответ правильный:
A known concentration of butane in nitrogen.35
What simple test can be carried out to check for leaks in a bulb type aspirator pump for a gas detecting instrument?
Ваш ответ правильный:
Nip the inlet line after squeezing the bulb to see if it stays deflated.36
What two types of sensor are normally used in portable oxygen analysers on board ship?
Ваш ответ правильный:
Paramagnetic.; Galvanic cell.37
What will happen to the meter reading, when using a non-catalytic heated filament combustible gas detector with a range setting of 0-100 % LEL in an atmosphere, containing a high concentration of hydrocarbon gas?
Правильный ответ:
Rise to a maximum and remain there until the concentration reduces.Ваш ответ:
Continuous unstable reading.38
What work related recommendations are covered by IMO Resolution A864 (20)?
Ваш ответ правильный:
The recommendations for entering an enclosed space on board a ship.39
What would a portable instrument employing a paramagnetic sensor normally be used for during enclosed space checks on board ship?
Ваш ответ правильный:
Checking the oxygen content in the atmosphere.40
What would be the effect, if any, on the meter reading of a catalytic filament type combustible gas indicator, if the oxygen content of the sample was less than 11 %?
Ваш ответ правильный:
The reading would be unreliable.41
What would be the likely outcome, if the combustion control of an independent inert gas generator, supplying inert gas to a cargo tank system, was incorrectly set, resulting in poor combustion?
Ваш ответ правильный:
Increased level of carbon monoxide in the inert gas.42
What would be the most common source of hydrogen sulphide gas being present in on board spaces of a ship?
Ваш ответ правильный:
Sour crude or petroleum products from sour crude in tanks.43
What would be the normal source of information, regarding the possible presence of a toxic gas, due to the carriage of a particular cargo?
Ваш ответ правильный:
Material safety data sheet for the cargo (MSDS).44
When calibrating an oxygen analyser, which two of the options given should normally be checked?
Ваш ответ правильный:
Zero setting.; Span (21 % by volume).45
When carrying out a span check of a combustible or hydrocarbon gas detector the sample gas should normally be taken from a gas bag, rather than direct from the gas canister? Why should this procedure be followed?
Ваш ответ правильный:
To avoid excess pressure or flow in the instrument.46
When carrying out checks of the atmosphere in a cargo tank following gas freeing how many levels in the tank should be taken to ensure, there are no variations in the tank atmosphere?
Ваш ответ правильный:
At least three levels.47
When obtaining a representative sample of the atmosphere of an enclosed space for purposes of determining the oxygen content, what action should be taken with the ventilation of the space?
Ваш ответ правильный:
It should be stopped for 10 minutes before sampling.48
Where would you expect to find specific procedures regarding entry into enclosed spaces and atmosphere testing for a vessel you are sailing on?
Ваш ответ правильный:
Safety Management Manual (ISM Manual).49
Which gas would be most likely to affect the reading from a refractive index type hydrocarbon gas measuring instrument?
Ваш ответ правильный:
Carbon dioxide.50
Which material is normally used to remove dirt and moisture from a gas sample prior to entry into a combustible gas indicator?
Ваш ответ правильный:
Cotton wool.51
Which material is recommended for the removal of carbon dioxide from a gas sample when measuring the hydrocarbon gas content of an inerted cargo tank atmosphere with a refractive index or infrared absorption type detector?
Ваш ответ правильный:
Soda lime.52
Which measuring range would be most likely on a single range combustible gas detector (explosimeter)?
Ваш ответ правильный:
0-100 % LEL.53
Which of the following toxicity threshold limit exposure terms would normally have the lowest numerical value?
Ваш ответ правильный:
TLV-TWA.54
Which of the following types of combustible and hydrocarbon gas instruments is usually referred to as an Interferometer?
Ваш ответ правильный:
Refractive index type.55
Which of the options given would normally be associated with colorimetric testing in relation to the detection of toxic gases?
Ваш ответ правильный:
Chemical gas detector tubes.56
Which term is normally used to describe the property of a gas, that has a harmful effect on a living organism as a result of a single short term exposure?
Ваш ответ правильный:
Acute toxicity.57
Which term is normally used to describe the property of a gas, that has a long term harmful effect on a living organism, as a result of repeated or long term exposure to even low concentrations of the gas?
Ваш ответ правильный:
Chronic toxicity.58
Which two of the following gases are likely to result in poisoning of the sensor element in a catalytic filament type combustible gas detector?
Ваш ответ правильный:
Hydrogen sulphide.; Carbon monoxide.59
Which two types of combustible/hydrocarbon gas detectors rely on resistance change with temperature for their operation?
Ваш ответ правильный:
Catalytic filament type.; Non-catalytic heated filament type.60
Which type of hydrocarbon gas detecting instrument uses thermal conductivity of the gas, as the means of measuring gas content in a sample?
Ваш ответ правильный:
Non-catalytic heated filament type.61
Why do galvanic type oxygen sensors have a limited life?
Ваш ответ правильный:
Anode is consumed during operation.62
Why is it necessary to check the oxygen content of an enclosed space atmosphere before using a catalytic filament type combustible gas detector (explosimeter)?
Ваш ответ правильный:
The instrument requires a minimum level of oxygen to function correctly.63
Why is purging of a cargo tank with inert gas normally carried out?
Ваш ответ правильный:
To reduce the hydrocarbon gas content to below the critical dilution level.64