In general, large pressure differentials produce high speeds through the valve or in downstream lines. While in liquid operation it generates turbulence and vibration on its own and produces high noise levels in gas operations. Speed ​​is inversely proportional to the pressure loss and is obtained as the stream moves to the constricted section, where the pressure reaches its maximum peak just after slightly passing the constricted section, where the pressure is at its lowest point. The following general rules apply to speed: liquids should generally not exceed 50 ft / s (15.2 m / s) (or 30 ft / s or 9 m / s when operated in cavitation); gas should not exceed Mach 1.0; gases and liquids The mixture (eg, flash operation) should not exceed 500 ft / s (152 m / s). This principle can vary (in terms of valve size), for example, small size valves can handle higher speeds normally, while larger valves can only handle lower flow rates. In general, the process liquid must maintain a velocity of less than or equal to 30 ft / s (9 m / s) when the temperature of the process liquid approaches saturation to prevent the fluid pressure from decreasing below the vapor pressure and creating cavitation. This 30 ft / s rule also applies to cavitated operations, where higher velocities result in larger cavitation damage to downstream lines. Lower speeds will also reduce flash and wear problems.