Orifices for speed control
Symbol orifices
In contrast to the throttle, the ratio of length L compared to flow diameter d is small.
Guide value: L / d <1.5
Hydraulics - Orifice function
Advantage of the orifice is that the viscous fluid friction is very low and thus the flow rate hardly depends on the viscosity. Disadvantage are the swirls especially at the exit point of the aperture.
Hydraulics - orifice - function and circuit example