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Difficulty: MediumCausal Detail Extraction

In closed-loop refrigeration systems, ambient moisture inadvertently introduced during servicing creates a significant operational hazard. Because the refrigerant undergoes a sudden pressure drop and severe cooling as it passes through the narrow orifice of the thermal expansion valve, any entrained water vapor instantly freezes into solid ice crystals. Consequently, this localized ice accumulation obstructs the valve opening, which chokes refrigerant flow to the evaporator and prevents the cooling cycle from functioning properly.

According to the passage, why does entrained water vapor freeze inside the thermal expansion valve?

  1. A
    Routine maintenance is performed on the closed-loop system
  2. B
    Refrigerant flow to the evaporator is completely blocked
  3. The refrigerant experiences a sudden drop in pressure and rapid coolingAnswer
  4. D
    The expansion valve mechanism suffers an electronic failure

Answer

The refrigerant experiences a sudden drop in pressure and rapid cooling
The passage explicitly uses the causal indicator 'Because' to explain that freezing occurs when the refrigerant undergoes a sudden pressure drop and severe cooling as it flows through the valve orifice.

Step-by-Step Solution

1
Identify the target effect in the stem (the freezing of entrained water vapor into ice crystals).
Targeted the specific phenomenon requiring a stated cause.
Clarifying the specific question prevents confusing background context with the direct cause.
2
Locate the explicit causal transition in the passage ('Because the refrigerant undergoes...').
Found the direct link: 'a sudden pressure drop and severe cooling as it passes through the narrow orifice.'
ASVAB causal detail questions rely on explicit transition words and direct textual evidence.
3
Match the textual cause to the correct answer choice.
Selected the choice stating that the refrigerant undergoes a sudden pressure drop and rapid cooling.
Eliminates distractors based on downstream effects, introductory context, and outside assumptions.

Key Concept

Identifying direct cause-and-effect relationships signaled by explicit causal transitions in a factual passage
Estimated Time:1m 0s
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Topics

Causal Detail Extraction

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