Function

To reduce the diameter of the orifice in the proper place of the pipeline, and when the liquid flows through the shrinkage orifice, the flow velocity becomes smaller or shrinks. The small cross section of flow velocity appears downstream of the actual lock, which is called the shrinkage cross section. At the condensation section, the pressure at the condensation section decreases greatly with the increase of flow velocity. When the velocity expands into a larger area, the velocity decreases and the pressure increases, but the downstream pressure will not completely restore to the upstream pressure. This is the result of larger internal turbulence and energy consumption. If the pressure PVC at the condensation section falls below the saturated vapor pressure PV at the corresponding liquid temperature, there will be steam and dissolution in the velocity. The gas in water escapes and forms small bubbles mixed with vapor. The lower the pressure, the more bubbles. When the pressure difference between the front and back of the pipeline is large, the throttle orifice plate is often added.

The principle is that when the fluid flows in the pipeline, the local resistance of the orifice plate reduces the pressure and energy loss of the fluid. This phenomenon is called throttle phenomenon in thermodynamics. This method is simpler than using control valve, but it must be selected properly. Otherwise, the liquid is prone to gas turbidity, which affects the safe operation of the pipeline.