HVAC · Practice-Exam-2 · Problem 51PDFSolution in PDF ↓
HVAC · Practice-Exam-2 · Problem 51
Problem & Solution
Video Synthesis
Topic: Pipe flow / fluid mechanics — The flow of 20 degree water through a hose with an inside diameter of 25 millimeters is at the lower boundary of the fully turbulent range.
Method: How long will it take to fill a 50,000 liter swimming pool?
Formula reference: formula, which is VD over and you can search that in the reference handbook as well.
Result: That number turns out to be 849.6.
Reference: search the reference handbook for fully turbulent, we'll find out
✅ Answer: D
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Student questions asked in live office hours about this problem
OH 124 · July 6, 2026
Q: If the problem says the flow is at the lower end of the turbulent range, should the Reynolds number be closer to 4,000?
A: No. In the handbook convention Dan referenced, 4,000 is around the transition/critical region, while the lower end of the turbulent range starts around 12,000. Since the problem explicitly says lower end of turbulent, 12,000 is the intended choice.