Head pressure in hydraulic calculations is expressed by multiplying vertical difference in feet by which constant?

• A. 0.434 psi per foot
• B. 0.5 psi per foot
• C. 1.0 psi per foot
• D. 2.0 psi per foot

Answer: (A)

Head pressure comes from the weight of a vertical column of liquid, so you use P = γ h, where γ is the fluid’s weight density and h is the height of the column. For water, γ is about 62.4 pounds per cubic foot, and converting to psi per foot gives 62.4 lbf/ft^2 divided by 144 in^2/ft^2, which is 0.433 psi per foot. Rounding to three decimals gives 0.434 psi per foot. So a 1 ft rise adds about 0.434 psi, a 10 ft rise about 4.34 psi, and you’d use a different constant if the fluid isn’t water.