Which of the following is NOT listed as a method to prevent cavitation in a pump-suction system?

• A. Increase suction head
• B. Increase suction pipe diameter (lower velocity)
• C. Increase elevation difference
• D. Keep fluid temperature low to reduce vapor pressure

Answer: (C)

Preventing cavitation in a pump-suction system focuses on keeping the suction pressure at the pump above the liquid’s vapor pressure by maximizing the available suction head and reducing pressure losses in the suction path. Raising the suction head increases the static pressure at the pump inlet, boosting the net positive suction head available and making cavitation less likely. Using a larger suction pipe diameter lowers flow velocity and the corresponding friction losses, so the pressure at the pump suction stays higher, again helping prevent cavitation. Keeping the fluid temperature low reduces the vapor pressure of the liquid, which means cavitation is less likely to occur for a given suction pressure. Increasing the elevation difference between the liquid source and the pump, however, lowers the suction head at the pump (the pump ends up higher relative to the liquid surface), reducing NPSHa and making cavitation more likely, so it’s not used as a cavitation-prevention method.