Orifice control

Orifice control

In hydraulics the term 'orifice' refers to a hole or inlet through which water must pass. Orifices restrict flows and hence they control the flows going into downstream pipes or channels with larger flow capacities.

Orifice control occurs when the inlet is fully submerged and rates of flow are governed by an orifice equation or the full pipe flow equation. In both of these, the flowrate is proportional to the square root of the water height, so that flows per increment of upstream water level are small compared to weir control situations.


 The following diagram indicates how orifice control can occur at a small inlet pit.

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