Which term describes the pressure loss or gain due to elevation?

• A. Hydrostatic Pressure
• B. Dynamic Pressure
• C. Back Pressure
• D. Atmospheric Pressure

Answer: (C)

Hydrostatic pressure. This is the pressure that results from gravity acting on the water column above a point. It changes with elevation because the weight of the fluid above changes as you go up or down. In water, roughly 0.433 psi are lost for every foot you rise, so lifting discharge elevation by 10 feet reduces gauge pressure by about 4.33 psi. Dynamic pressure, by contrast, comes from fluid motion; back pressure is resistance to flow downstream; atmospheric pressure is the ambient air pressure outside the system. So the term describing pressure change due to elevation is hydrostatic pressure.