How is the hydraulic grade line defined_________________?
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Answer: B. never above the energy grade line
Explanation
The energy grade line accounts for both velocity head and static pressure head in flowing fluids. The hydraulic grade line represents only the pressure head and elevation head without velocity components. Since total energy always exceeds static pressure head by the velocity head, the hydraulic grade line stays below it. Energy grade line height represents the total mechanical energy per unit weight of the fluid. Hydraulic grade line height corresponds to the piezometric head observed in static pressure taps. Frictional losses cause both grade lines to slope downward in the direction of fluid flow.
Municipal water distribution engineers use these grade lines to design pumps and check for cavitation risks. Plotting grade lines helps identify problem areas where pipe constrictions cause excessive energy drops. Understanding energy grades ensures water flows properly through hilly terrain without external booster pumps. The hydraulic grade line can fall below the pipe centre line if sub-atmospheric pressure conditions occur. Claiming it is always sloping downward ignores pumps that can locally raise the hydraulic grade line. Only the restriction that it never rises above the energy grade line applies universally.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
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