What is an Orifice?

An orifice is a small opening provided on the side or bottom of a tank, through which a fluid is flowing. The opening can be of any shape or cross-section, like rectangular, triangular or circular. The orifices may discharge fluid into the atmosphere or from one tank to another.

Orifices are classified based on the shape or the cross-sectional area as:

• Rectangular orifice
• Circular orifice
• Triangular orifice and
• Square orifice

Orifices are classified based on the size of the orifice and the head of fluid above the orifice as:

• Small orifice and
  
• Large orifice

Depending on the shape of the upstream edge of the orifices, they are classified as:

• Sharp-edged orifice and
• Bell-mouthed orifice

They are also classified based on the nature of the discharge as:

• Partially submerged or drowned orifice
• Fully submerged or drowned orifice
  
• Free discharging orifices