Pressure head is best described as which?

• A. The vertical distance from the point of pressure measurement to the hydraulic grade line
• B. The energy per unit weight at the point
• C. The horizontal distance from pump to valve
• D. The velocity head in pipe

Answer: (A)

Pressure head is the height of a column of water that would produce the same pressure at that point, which equals p/γ. In a piping network, the hydraulic grade line represents z + p/γ, so the vertical distance from the measurement point up to the hydraulic grade line is exactly p/γ. That makes the vertical distance to the HGL the best description of pressure head. The total energy per unit weight at the point would include elevation and velocity heads as well (total head), not just pressure head, and velocity head is a separate term v^2/(2g). The horizontal distance from pump to valve has no bearing on pressure head.