I know that different geometries of piping, orifices etc... have different critical Reynolds values. If the value is exceeded laminar stream will turn to a turbulent form which causes a variety of problems. But why shouldn´t the value be too low?
I.e. for pressure piping up to around 300 bars I assume that I have to be inbetween of 3 to 12 m/s.
Do too low velocities cause problems like cavitation? What are the reasons?
FYI: To have a practical example. I am asking because I want to design a hydraulic system but I only have a NG25 valve available but NG6 is probably already enough.