Restriction orifice (RO) is mainly used to achieve controlled or restricted flow of process medium. The orifice offers a restriction to the process flow and the pressure head drops from the upstream to the downstream. The permanent pressure loss by the device is the intended pressure drop for which it is sized. The area of the orifice determines the rate of flow at the outlet of a given process fluid for the specified pressure and temperature.
The responsibility of final restriction orifice sizing, selection & supply rests with the supplier. Design and sizing of restriction orifice may require review by specialist for stress and noise related evaluation.