TFS · Hydraulic & Fluid Applications · Problem 28PDFSolution in PDF ↓
TFS · Hydraulic & Fluid Applications · Problem 28
Problem & Solution
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Topic: Pipe flow / fluid mechanics — 0.02 cubic feet per second of 120 degree of water flows in a 1-inch nominal type L copper pipe with relative roughness of 0.002.
Method: The length of pipe is 90 feet and the minor losses have a K value of 1.5.
Key values: 2.5 psi, 90 feet and the minor losses have a K value of 1, 12 feet quantity squared and then I
Reference: search properties of water and we can find out that new equals 0
✅ Answer: A
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Student questions asked in live office hours about this problem
OH 51
Q: Why wasn't the density of water at 120°F used instead of the standard 62.4 lb/ft³ when applying the conversion factor to go from feet to PSI?
A: The density difference between 120°F (61.7) and standard conditions (62.4) is only about 1%, so using the standard value is a reasonable judgment call to save time. On the PE exam, you need to balance precision with efficiency—focus on problem framing and overall strategy rather than getting bogged down in 1% accuracy details when you have 80 problems to solve.