TFS · Practice Exam 1 · Problem 66PDFSolution in PDF ↓
TFS · Practice Exam 1 · Problem 66
Problem & Solution
Video Synthesis
- Problem: 10,000 gallons per hour of fuel oil with a specific gravity of 0.86 is delivered to an emergency generator by 90% efficient pump.
- Approach: Often times probably more times than not for the head term we just work in feet, but occasionally we want to use this other equation which says that the hydraulic horsepower equals...
- Key values: 90 %, 2 in, 30 psi, 30 PSI
- Reference: reference handbook
- Result: 166.66 times 34.7 divided by 1714 gives us 3.37 horsepower.
- ✅ Answer: D
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Student questions asked in live office hours about this problem
OH 74
Q: Why isn't the 30 psi G pressure on the discharge side converted to psi A by adding 14.7 psi, like the solution doesn't do this?
A: Both pressures are already in gauge pressure (G), so you don't convert between them—the 'G' notation means they're already referenced to atmospheric pressure. You only convert to absolute (A) if you actually need absolute pressure for the calculation, but for finding the pressure difference (delta P) between two points, gauge pressures can be subtracted directly.