Why is it said that flow-closed valves are more prone to flashing than flow-open valves
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The fluid velocity is highest at the valve seat; assuming that the pressure there is below the saturated vapor pressure, vaporization occurs. According to personal analysis, the flow-closed type has low resistance and minimal pressure loss; at the same inlet pressure, the outlet pressure of the flow-open type is lower than that of the flow-closed type, and it is more difficult for the outlet pressure of the flow-open type to rise above the saturated vapor pressure, while the flow-closed type should flash more easily. Why do the sources state that plug-type valves are more prone to flashing than plugless-type valves?
For reference: Basic Knowledge for Instrumentation Technicians (22) – Everything About Actuators 4 – Characteristics of Flow-Blocking Valves. Basic Knowledge for Instrumentation Technicians (17) – Plug Flow 3 – Regarding Control Valves 2