A hydronic pump must overcome 54 psi of pressure drop. Using 2.31 ft of water per psi, what pump head is closest?
Correct Answer
A) 125 ft
Head is 54 x 2.31 = 124.74 ft, or about 125 ft. Other choices use a lower conversion, round down too far, or add an unsupported safety factor.
Why This Is the Correct Answer
Head is 54 x 2.31 = 124.74 ft, or about 125 ft. Other choices use a lower conversion, round down too far, or add an unsupported safety factor.
Why the Other Options Are Wrong
Option B: 100 ft
pump head, choice a: 100 ft omits a required add-on/subtraction; the numeric gap is 25.
Option C: 115 ft
pump head, choice b: 115 ft omits a required add-on/subtraction; the numeric gap is 10.
Option D: 150 ft
pump head, choice c: 150 ft adds an extra unstated add-on/subtraction; the numeric gap is 25.
Memory Technique
Store pump head with its last math move; nearby answers are usually unfinished versions of 125 ft.
Reference Hint
Open Mechanical and Electrical Systems for Construction Managers, 4th Ed., 2024; use the index entry or section for "Pump pressure-to-head conversion" to confirm that Head is 54 x 2.31 = 124.74 ft, or about 125 ft.
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