Boiler classification: A “high-pressure” boiler is commonly defined as one that generates steam at pressures exceeding which threshold value (use kg/cm² as the unit)?
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A10
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B30
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C50
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D80
Answer
Correct Answer: 80
Explanation
Introduction / Context:Boilers are categorized by pressure level because materials, safety valves, drum design, and water–steam circuitry depend strongly on operating pressure. Recognizing the conventional boundary for “high-pressure” helps in selecting codes and standards, and in anticipating efficiency and superheat levels.
Given Data / Assumptions:
- Conventional textbook/industry classification for stationary boilers.
- Pressure unit is kg/cm² (approximately bar).
- Focus on threshold commonly cited in competitive exams and practice.
Concept / Approach:Traditional classifications consider boilers with steam pressure above about 80 kg/cm² as “high-pressure.” Examples include Benson, Lamont, and Loeffler types. Below this, units are often termed low- to medium-pressure with simpler drum and circulation arrangements.
Step-by-Step Solution:
Map common categories: low/medium vs high-pressure.Identify the threshold of ≈80 kg/cm² used in many references.Select 80 kg/cm² as the boundary value in the options.Relate high pressure to higher efficiencies and superheat capability.Note implications for water treatment and materials selection.Verification / Alternative check:Standard boiler engineering texts list high-pressure boilers as those exceeding roughly 80 kg/cm², consistent with the given choices.
Why Other Options Are Wrong:
- 10, 30, 50: Typical of low to medium pressure ranges; not the usual “high-pressure” designation.
Common Pitfalls:Confusing “supercritical” classification (beyond critical pressure) with merely “high-pressure”; these are distinct categories.
Final Answer:80