No. 0426 Gas measurement, measuring instruments

Q: When carrying out checks of the atmosphere in a cargo tank following gas freeing, at how many levels in the tank should samples be taken to ensure there are no variations in the tank atmosphere? Select the ONE correct answer.
A: From various positions, and at least three levels

Q: Which of the options correctly fills the gap? ‘The inert gas supplied must contain no more than ___ oxygen by volume to prevent flammable or explosive conditions within a cargo space.’
xx A: 10%
XX A: 8%

Q: Which of the options correctly fills the gap? ‘The inert gas system must be capable of maintaining a tank atmosphere of no more than __ oxygen by volume.’
xx A: 10%

Q: What are the two main reasons for measuring the oxygen content of an enclosed space onboard a ship?
A: To check if the oxygen content is low enough to avoid flammable mixtures. To ensure the oxygen content is sufficient to allow safe entry.

Q: Carry out a leak test. A: Sampling pump and hose.
Dry out moisture absorbent types. A: Filter.
Keep spares in case the instrument is needed while charging. A: Battery.
Replace if difficulty calibrating. A: Sensor.

Q: What TWO types of sensor are normally used in portable oxygen analysers onboard ship? Select the TWO correct answers.
A: Paramagnetic. Electrochemical.

Q: Which type of hydrocarbon gas detecting instrument uses thermal conductivity of the gas as the means of measuring gas content in a sample? Select the ONE correct answer.
A: Non-catalytic heated filament type.

Q: Which gas would be most likely to adversely affect the reading from a refractive index type hydrocarbon gas measuring instrument?
A: Carbon dioxide

Q: Which TWO of the following gases are likely to result in poisoning of the sensor element in a catalytic filament type combustible gas detector?
A: Hydrogen sulphide, Carbon monoxide

Q: Which test gas should be used to check the span during calibration of a combustible gas or hydrocarbon gas detector? Select the ONE best answer.
A: A known concentration of butane in nitrogen.

Q: 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? Select the ONE correct answer.
A: Divide the total reading on the tube by 8.

Q: What should you do if an electrochemical gas monitor fails a bump test? Select the TWO BEST answers.
A: Replace the sensor. Return to the manufacturer for reconditioning.

Q: 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?
A: The inerting operation should be stopped for at least 30 minutes before introducing sampling equipment into the tank.

Q: Which of the options correctly completes the following statement? ‘Oxygen analysers should be calibrated… Select as many answers as you think are correct
A: …at regular intervals during prolonged usage.’ …before each use.’

Q: 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 the ONE BEST answer.
A: All the other answers.

• This topic was modified 3 months, 1 week ago by Admin.
• This topic was modified 3 months, 1 week ago by Admin.