During drafting, the water surface must be no more than how many feet below the centerline of the pump intake?

During drafting, the water surface must be no more than how many feet below the centerline of the pump intake?

• A. 6 Feet
• B. 8 Feet
• C. 10 Feet
• D. 12 Feet

Answer: (C)

Drafting relies on keeping the intake submerged enough to avoid drawing air into the pump. The deeper the water surface is below the pump’s intake centerline, the more suction the pump must develop. If the surface is too far below, the suction pressure can drop toward the water’s vapor pressure, causing air to be drawn in and the pump to lose prime. Keeping the surface no more than ten feet below the centerline provides a reliable margin for priming and steady flow with standard equipment. That’s why ten feet is the correct maximum.

Drafting relies on keeping the intake submerged enough to avoid drawing air into the pump. The deeper the water surface is below the pump’s intake centerline, the more suction the pump must develop. If the surface is too far below, the suction pressure can drop toward the water’s vapor pressure, causing air to be drawn in and the pump to lose prime. Keeping the surface no more than ten feet below the centerline provides a reliable margin for priming and steady flow with standard equipment. That’s why ten feet is the correct maximum.