Why is pump suction bigger than discharge?

The pump suction is typically larger than the discharge to reduce the velocity of the fluid entering the pump, which helps to minimize turbulence and the risk of cavitation. A larger suction pipe allows for a smoother and more efficient flow into the pump, ensuring that it can operate effectively without drawing in air or creating pressure drops. This design choice also helps accommodate variations in flow rates and reduces the potential for blockages. Overall, it enhances the pump's performance and longevity.