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Difficulty: MediumAuthor's Primary Purpose

To prevent catastrophic explosions in cargo storage compartments, maritime fuel transport vessels utilize inert gas systems (IGS) during cargo discharge and transit. Hydrocarbon vapors present in fuel tanks require a specific concentration of oxygen to ignite. As liquid fuel is pumped out of a tank, an explosive mixture of vapor and air could rapidly form in the expanding empty space. To mitigate this hazard, the IGS introduces processed, oxygen-depleted flue gas or pure nitrogen into the tank, reducing the atmospheric oxygen content well below the critical combustion threshold of eight percent. Maintaining this continuous positive pressure of inert gas ensures that the vapor space remains nonflammable, regardless of ambient temperature fluctuations or electrostatic discharge risks.

Which of the following best describes the author's primary purpose in the passage?

  1. A
    to outline general safety protocols for operating maritime cargo transport vessels
  2. to explain how inert gas systems prevent combustion in fuel transport tanksAnswer
  3. C
    to establish the exact chemical composition of hydrocarbon vapors during cargo discharge
  4. D
    to persuade maritime operators to replace flue gas systems with pure nitrogen generators

Answer

to explain how inert gas systems prevent combustion in fuel transport tanks
The passage is an expository explanation of a technical system. It outlines the danger of hydrocarbon vapor combustion when liquid fuel is discharged and systematically explains how inert gas systems introduce oxygen-depleted gas to keep the environment below the combustion threshold. Therefore, the primary purpose is to explain how these systems function to prevent fire and explosion.

Step-by-Step Solution

1
Analyze the text structure and core topic
The passage defines a specific hazard (hydrocarbon vapor combustion during fuel discharge) and details how inert gas systems (IGS) mitigate it.
Determining what the passage focuses on as a whole reveals the overarching communication goal.
2
Evaluate the author's tone and rhetorical objective
The tone is neutral, technical, and expository; it informs the reader of the working mechanism rather than arguing for policy change.
Identifying rhetorical intent prevents confusing an informative text with an argumentative or persuasive one.
3
Match the synthesized purpose to the corresponding option
The statement describing the explanation of how inert gas systems prevent combustion accurately captures the entire scope of the text.
The correct primary purpose must encompass the whole passage without being overly broad or narrowly focused on one detail.

Key Concept

Author's Primary Purpose
Estimated Time:1m 0s
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Author's Primary Purpose

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