Which statement correctly describes Total Head in suction-lift tests?

• A. It is the sum of the total discharge head and the total suction lift
• B. It is equal to the discharge head plus suction head
• C. It equals the discharge head plus suction lift
• D. It equals the discharge head only

Answer: (C)

Total head in suction-lift tests represents the energy the pump must impart to move water from the source to the discharge point. It is found by adding the discharge head to the suction lift. The discharge head accounts for the energy on the discharge side (the height water is raised at discharge, including any velocity/pressure effects there), while the suction lift is the vertical distance the water must be lifted from the water source up to the pump suction. Adding them gives the total head the pump must overcome. Using suction head would pull in the pressure at the suction side, which isn’t what this test measures, and using only the discharge head would ignore the energy needed to lift water to the suction, underestimating the required head.