Suction head exists where the total suction head is above atmospheric pressure.

Suction head exists where the total suction head is above atmospheric pressure.

• A. Only at sea level
• B. False
• C. True
• D. Only when discharge head is zero

Answer: (C)

Suction exists when the pressure at the pump suction is at least as high as the ambient atmospheric pressure, so liquid can be drawn into the pump. The suction head is the pressure head at the suction, expressed as an equivalent height of liquid, and it includes static and velocity head. If the total suction head (the suction-side pressure head) is above atmospheric pressure, there is positive suction pressure at the inlet, allowing the pump to take in liquid. This isn’t limited to sea level—the concept holds wherever atmospheric pressure is the reference; lifting capability depends on the suction pressure relative to atmosphere. So, the statement is true.

Suction exists when the pressure at the pump suction is at least as high as the ambient atmospheric pressure, so liquid can be drawn into the pump. The suction head is the pressure head at the suction, expressed as an equivalent height of liquid, and it includes static and velocity head. If the total suction head (the suction-side pressure head) is above atmospheric pressure, there is positive suction pressure at the inlet, allowing the pump to take in liquid. This isn’t limited to sea level—the concept holds wherever atmospheric pressure is the reference; lifting capability depends on the suction pressure relative to atmosphere. So, the statement is true.