Welcome to the website where you can pass online the CES CBT CD-7049 test on the subject «TOTS 1C-Fixed and Portable Gas Detections Systems». Practice like this will help you as a marine specialist improve your knowledge with the help of online studying and appraisal practice. CES based on practical information and marine specialists experience.
CES tests developed for evaluating seaman basic knowledge by Seagull Company (rebranded as «OTG»), is an evaluating online-tool, used for revealing any professional preparation needed in specific fields of knowledge, defined by STCW.
CES tests have proven themselves as good tools for the selection and recruitment process, as well as advancing the level of knowledge of the current officers and crew. Ocean Technologies Group use various subjects for question creation, which includes:
Crowd and Crisis Management;
Integrated Navigation System (INS);
Ballast water management;
Handling and Stowage;
Vessel operation management and safety;
Marine engineering;
Maintenance and repair, etc.
Current test contains Seagull CES questions on the subject «TOTS 1C-Fixed and Portable Gas Detections Systems». Those questions can be used for competence verification specialist capable of preventing accidental situations related with transporting safety, or also for self-examination.
«TOTS 1C-Fixed and Portable Gas Detections Systems» subject includes theoretical and practical information about advanced training for work on any type of vessel. The test provides essential advanced training for personnel working on all types of vessels. This comprehensive program focuses on both the understanding and practical application of gas detection technologies. Participants gain in-depth knowledge of various fixed and portable gas detection systems, including their operational principles and limitations. The training covers the identification of potential gas hazards commonly encountered on vessels, such as flammable, toxic and asphyxiant gases. Participants learn proper procedures for calibrating, maintaining and troubleshooting gas detection equipment to ensure accuracy and reliability. Furthermore, the course emphasizes the correct interpretation of readings and appropriate response actions in emergency situations. Upon completion, trainees are equipped with the skills and knowledge to effectively monitor and mitigate gas-related risks, contributing to a safer working environment onboard. This training is crucial for compliance with international safety regulations and best practices in the maritime industry.
On this site Crew Evaluation System Test on the subject «TOTS 1C-Fixed and Portable Gas Detections Systems» contains 56 questions you need to answer with no possibility to go back to previous question. Therefore, we recommend carefully reading each question and making decision with no hurry. In case you have some difficulty answering, you have also possibility to request a hint.
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* Some questions may have more than 1 correct answer.
A fixed combustible gas detection system can only detect a limited range of substances. What are these substances?
Hydrocarbon gases up to the Lower Flammable Limit.
Chemical gases up to 100 %.
Oxygen content up to 21 %.
Smoke and combustion products.
A fixed combustible gas detection system should not be used to assess compartments for entry purposes. Why not?
Because it does not give an accurate enough reading.
Because it does not indicate the oxygen content or the presence of toxic gases.
Because many spaces are being monitored, and the origin of the sample is not certain.
Since the sample takes some time to pass through the system, the reading may not be current.
After washing and gas-freeing from a toxic cargo, what type of gas detection equipment should you use before entering a cargo tank?
A tankscope.
An Explosimeter.
An infrared gas detector.
Chemical indicator tubes.
An Explosimeter cannot be used in an inerted atmosphere. Why not?
Because small particles will clog the filters.
Because adequate oxygen is required for combustion of the filament.
Because the inert gas poisons the filament.
Because the presence of carbon dioxide will increase the readings.
Cotton filters are sometimes used with hydrocarbon gas detectors. What is their purpose?
To remove water from the sample.
To prevent chemical contamination of the sample.
To remove dust from the sample.
To stop pressure surges in the sample line.
For how long must the ventilation of a space be stopped before conducting tests of the atmosphere for an Enclosed Space Entry?
10 minutes.
30 minutes.
Briefly, while the tests are being carried out.
The ventilation should be run continuously.
How many different locations within a tank should be sampled to test the atmosphere before entering a tank?
As close as possible to the centre of the tank.
At least three.
At various depths, and through as many openings as possible.
In one position, at a minimum of three levels.
How will leaks in the sample pipework affect the operation of a fixed gas detection system?
It will cause failure due to high flow rate.
It will cause failure due to low suction pressure.
It will cause lower readings due to dilution of the sample.
It will cause higher readings due to increased flow rate.
How will leaks in the sampling line affect the operation of portable gas detection equipment?
It will cause lower readings due to dilution of the sample.
It will cause failure due to high flow rate.
It will cause failure due to low suction pressure.
It will cause higher readings due to increased flow rate.
If an Explosimeter is calibrated using span gas containing 1 % butane in air, what reading may be expected?
Approximately 1 % Lower Flammable Limit.
Approximately 10 % Lower Flammable Limit.
Approximately 50 % Lower Flammable Limit.
Approximately 100 % Lower Flammable Limit.
Many fixed gas detection systems have high and low sampling points. Why is this so?
In order to ensure that all of a compartment is sampled.
In order to ensure that suction pipe runs are of a similar length.
So that they can be switched to account for temperature variations in the sample.
So that they can be switched for cargos of different vapour density.
Many fixed gas detection systems monitor the atmosphere in the ballast tanks. What precautions must be taken on loaded passages?
All sample lines must be isolated to prevent any cargo from entering the system.
The alarm function must be switched off to prevent a continuous alarm condition.
The system can be run as normal, but all alarms must be investigated.
Sample lines from ballast tanks must be isolated to prevent water from entering the system.
Multi-toxic gas detectors normally use electro-chemical detectors. What level of accuracy can be expected?
Approximately 1-5 ppm.
Approximately 100-500 ppm.
Approximately 10 % by volume.
Approximately 30 % by volume.
Some chemical gases will not be detected by a fixed combustible gas detection system. How does this restrict the use of the system?
The flammability readings may be unreliable.
The system cannot be used if the ship is carrying chemicals.
The system cannot be used to assess the level of toxic gas.
The system cannot be used under very cold conditions.
Span gas is generally used for calibration of a fixed gas detection system. What is the composition of this gas?
Approximately 1 % butane in air.
Approximately 40 % propane in air.
A proprietary mixture of nitrogen and carbon dioxide.
Pure nitrogen.
The flammable limits for the vapours given off by clean products such as motor or aviation gasoline can be represented by those of butane. What is the Lower Flammable Limit of butane?
1,9 % by volume in air.
5,9 % by volume in air.
9 % by volume in air.
19 % by volume in air.
The flammable limits for the vapours given off by crude oil can be represented by those of propane. What is the Lower Flammable Limit of propane?
2,2 % by volume in air.
5,2 % by volume in air.
10 % by volume in air.
22 % by volume in air.
What effect will inert gas have on the operation of a tankscope?
None. The sensor does not require oxygen.
It will increase the reading by increasing the temperature of the filament.
It will reduce the reading by contaminating the sensor.
Small particles may clog the filters.
What effect will inert gas have on the operation of an Explosimeter?
It will inhibit operation, as the sensor requires oxygen.
It will reduce the reading by contaminating the sensor.
None. The sensor does not require oxygen.
Small particles may clog the filters.
What effect will inert gas have on the operation of an infrared type gas detector?
It will Increase the reading by increasing the temperature of the chamber.
It will reduce the reading by contaminating the sensor.
Small particles may obscure the mirrors.
None. The instrument is not affected by the absence of oxygen.
What equipment is required to test an enclosed space for the presence of toxic gas before entry?
A tankscope.
An Explosimeter.
An oxygen meter.
Chemical absorption tubes.
What indication will be given by an Explosimeter in the case of oxygen deficiency?
No indication.
Approximately 20 % of the Lower Flammable Limit.
Full scale deflection.
The indication will be erratic and jumpy.
What instrument should you use to test for very low levels of oxygen before loading a sensitive cargo?
A paramagnetic oxygen analyser.
An Explosimeter.
An infrared gas detector.
Chemical indicator tubes.
What instruments must be provided to comply with the statutory requirements for ships fitted with an inert gas plant?
An Explosimeter and an oxygen analyser.
An oxygen analyser and an instrument to measure the percentage of hydrocarbon gas in an inerted atmosphere.
At least two instruments to measure the percentage of hydrocarbon gas in an inerted atmosphere.
At least two instruments to measure the percentage of oxygen in an inerted atmosphere.
What instruments should be used to check the atmosphere of an enclosed space before entry?
An Explosimeter, a portable oxygen analyser, and a toxic gas meter if required.
A personal gas detector and a personal toxic gas alarm if required.
A tankscope, an oxygen analyser, and a toxic gas meter if required.
An Explosimeter, and a toxic gas meter if required.
What is a «Pellistor»?
It’s a balancing resistor between the sensing element and a fixed compensator.
It’s a filter which prevents the spread of flame.
It’s a poison resistant catalytic filament.
It’s a protective device which removes contaminants.
What is a «Sintered Filter», and what is its purpose?
It’s a flashback arrestor used to prevent flame from escaping from the combustion chamber.
It’s a cotton wad used to prevent water from entering the combustion chamber.
It’s a fine metal filter used to prevent contamination of the sensor.
It’s an electronic device used to smooth the signal from the sensor.
What is the composition of the span gas generally used for calibration of an Explosimeter?
Approximately 1 % butane in air.
Approximately 40 % propane in air.
A proprietary mixture of nitrogen and carbon dioxide.
Pure carbon dioxide.
What is the composition of the span gas generally used to zero a portable oxygen analyser?
High purity nitrogen or carbon dioxide.
Approximately 2 % propane in air.
Approximately 20 % propane in air.
Fresh air.
What is the gas concentration alarm level on a fixed gas detection system?
3 % of Lower Flammable Limit.
10 % of flammable gas.
30 % of Lower Flammable Limit.
30 % of flammable gas.
What is the main reason for fitting a fixed gas detection system on a ship?
To indicate when a flammable atmosphere exists in a compartment.
To indicate that ventilation systems are working correctly.
To show that compartments are safe for entry.
To show that compartments are safe for hot work.
What is the principle by which a thermal conductivity meter works?
To show a change in temperature of an electrically heated resistance element, due to heat loss to the gas sample by conduction.
To show a change in the conductivity of a heated gas sample relative to that of air.
To show change in the density of a heated gas sample relative to that of air.
To show a change in resistance of an electrically heated resistance element, due to heat loss to the gas sample by conduction.
What is the principle by which an infrared gas detector operates?
It senses the level of absorption of infrared radiation in the sample.
It compares the electrical resistance of the sample with fresh air.
It compares the relative density of a sample which has been heated by an infrared source.
It measures the resistance of a sample which has been heated by an infrared source.
What is the principle by which chemical absorption indicators operate?
By passing the sample through a proprietary chemical, the gas concentration is indicated by its changing colour.
To compare the chemical absorption rate of the sample with fresh air.
To sense the proportion of a sample which is absorbed by a catalyst.
To show whether a toxic gas will be absorbed by the human body.
What measurements can be made using a Combustible Gas Indicator (Explosimeter)?
Flammable gas up to the Lower Flammable Limit.
Flammable gas in an inert atmosphere.
Flammable gas up to 100 % concentration.
Toxic gas up to the threshold limit value.
What operational tests should be made routinely before using a gascope?
Checking the battery level and self-testing alarm functions.
Checking the battery level and zero using fresh air.
Checking the battery level and zero using nitrogen or carbon dioxide.
Checking the reference point with span gas and zero using atmospheric air.
What operational tests should be made routinely before using a tankscope?
Checking the battery level and zero using fresh air.
Checking the battery level and self-testing alarm functions.
Checking the battery level and zero using nitrogen or carbon dioxide.
Checking the reference point with span gas and zero using atmospheric air.
What operational tests should be made routinely before using an Explosimeter?
Checking the battery level and self-testing alarm functions.
Checking the battery level and zero using nitrogen or carbon dioxide.
Checking the battery level and zero using fresh air.
Checking the reference point with span gas, and zero using atmospheric air.
What operational tests should be made routinely before using an oxygen analyser?
Check battery level, reference point with atmospheric air (21 %), and zero using nitrogen or carbon dioxide.
Check battery level, reference point with span gas, and zero using nitrogen or carbon dioxide.
Check the battery level, and self-test the alarm functions.
Check the reference point with span gas and zero using atmospheric air.
What property of oxygen is utilised in a paramagnetic oxygen analyser?
Oxygen molecules will break up in a magnetic field.
Oxygen is strongly attracted to a magnetic pole.
The electrical resistance of oxygen changes in a magnetic field.
The strength of a magnetic field is reduced in the presence of oxygen.
What range of flammable gas can be detected by a catalytic resistance detector?
0-10 % gas.
0-10 % Lower Flammable Limit.
0-100 % gas.
0-100 % Lower Flammable Limit.
What range of flammable gas can be detected by a thermal conductivity meter?
0-10 % gas.
0-10 % Lower Flammable Limit.
0-100 % gas.
0-100 % Lower Flammable Limit.
What range of flammable gas can be detected by an infrared type detector?
0-10 % gas.
0-10 % Lower Flammable Limit.
0-100 % gas.
0-100 % Lower Flammable Limit.
What task can a personal multi-gas detector be used for?
For monitoring atmospheric conditions during an enclosed space entry.
For checking the atmosphere of a ballast tank before entry.
For testing an enclosed space before starting hot work.
For testing the atmosphere of an open space before starting hot work.
What type of gas detection equipment should you use to test the atmosphere before starting hot work?
A personal gas detector.
A toxic gas meter.
An oxygen analyser.
A Combustible Gas Indicator (Explosimeter).
What type of sensor is fitted in a tankscope?
A non-catalytic heated filament.
A catalytic filament resistor.
A magnetic induction sensor.
A PT100 temperature sensor.
What type of sensor is fitted in an Explosimeter?
A gas diffusion filter.
A catalytic filament resistor.
A magnetic resonance chamber.
A non-catalytic heated filament.
What will be the effect of hydrogen sulphide on the reading shown on a Combustible Gas Indicator (Explosimeter)?
It will give a zero reading by destroying the sensor.
It will have no effect because it is non-flammable.
It will increase the reading by raising the sensitivity of the sensor.
It will reduce the reading by contaminating the sensor.
What would you use a personal oxygen meter for?
For checking the atmosphere of a ballast tank before entry.
For monitoring atmospheric conditions during an enclosed space entry.
For testing an enclosed space before starting hot work.
For testing the atmosphere of an open space before starting hot work.
When changing high purity cargo grades, what instrument should be used to ensure that tanks are free of the previous product?
Chemical indicator tubes.
A tankscope.
An Explosimeter.
An infrared gas detector.
When starting to test a sample using a Combustible Gas Indicator (Explosimeter), the needle immediately flicks to maximum deflection, then returns to zero. What is indicated?
That the flammable gas concentration is above the Lower Flammable Limit.
That the battery is incorrectly fitted.
That the instrument was not warmed up, but is now working correctly.
That the sensor element has been contaminated by toxic gas.
When using chemical absorption tubes, why must you use the exact number of pump strokes specified in the instructions?
Because all tubes require the same number of strokes.
It is not necessary to use the exact number stated, it is only for general guidance.
To ensure that the correct volume of sample gas is passed through the tube.
So that the results of all your tests are based on the same data.
Why is it necessary to use a water-retaining filter in the sample line of an oxygen analyser?
Because water vapour in the sample will cause damage to the measuring cell.
Because water in the sample will corrode the internal parts of the instrument.
Because water reacts with the measuring cell, giving a false reading.
Because water will build up in the sample line, reducing the flow.
Why must chemical absorption tubes only be used with pumps from the same manufacturer?
Because the pump and tube are matched to ensure that the correct volume of sample gas is tested.
Because the tubes will not fit correctly into another manufacturer’s pump.
Because using different tubes breaks the terms of the contract with the manufacturer.
Because using the wrong tubes may lead to contamination of the pump.
Why must the tank atmosphere be sampled at a variety of positions when testing before entry?
To allow for the density of the gas and to ensure that any collected in dead spots is detected.
To ensure that enough gas is drawn through the equipment to avoid it remaining in the sampling line.
To make sure that the detection equipment is working correctly.
To obtain an average reading throughout the tank.
Why should you avoid high sample pressure when using an Explosimeter?
If the flow rate is too high, the instrument does not have time to measure the gas concentration.
If the pressure is too high, it could cause an explosion inside the instrument.
The pressure may damage the catalytic filament.
The pressure may burst the sampling hose.
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