What is the difference between cavitation and flashing?
Flashing happens in the control valve if the liquid pressure drops to the value below its vapor pressure hence it may form vapor component (like bubble). Similar to flashing, the vapor is formed in cavitation in the same way, the difference is that the liquid pressure is increasing to a value over its vapor pressure during pressure recovery in which makes the vapor turn back into liquid state afterwards.
During engineering design, how to select control valve which expected to experience flashing condition and cavitation condition?
Flashing could be anticipated by hardened material trim therefore to overcome flashing, the selected control valve shall have hardened material trim. However, hardened material trim is not sufficient to handle cavitation. Anti-cavitation trim shall be used otherwise the system design itself should be changed so cavitation is avoided.