Problem Solution

Cavitation occurs when the absolute pressure is less than or equal to the vapor pressure (p_v), so that the water is allowed to "boil".

For water temperature of 50 ^oC, the vapor pressure is 12.33 kPa. Since the operating pressure of the pump on the inlet side is 6 kPa, which is less than the p_v, cavitation will occur.

On the other hand, for water temperature of 20 ^oC, the vapor pressure is 2.338 kPa. The operating pressure of the pump on the inlet side is now greater than the p_v, hence cavitation will not occur.