Orifice

ORIFICE CALCULATOR

The orifice equation is used to analyse the flow through a hole through the side of a vessel.

  • Q = Discharge (flow rate).
  • Cd = Co-efficient of discharge (difference between theoretical and real discharge).
  • A = Cross sectional area
  • h = Depth from center of orifice to upstream water level (free discharge orifice) or difference between upstream and downstream water level (drowned orifice).

However for large orifices (Height greater than depth/5) under free discharge the equation above is no longer considered valid due to the variation in flow velocity across the orifice. For rectangular orifices the following equation can be used as it integrates over the orifice's height. No easy integration is available for large circular orifice's and as such they are not included in the calculator.

  • b = Rectangular orifice width.
  • H2 = Depth from bottom of orifice to upstream water level
  • H1 = Depth from top of orifice to upstream water level


I want to find the of my

Cross Section Input

Width m
Height m
Rectangular channel diagram Orifice diamgram

Cross Section Input

Pipe Diameter m
Circular channel diagram Orifice diagram

Other Inputs

Small orifice only for circular orifice.

Depth to Bottom of Orifice m
Depth to Downstream Water Level m
Coefficient of Discharge

Outputs

Average Velocity m/s
Flow Discharge m³/s

Other Inputs

Small orifice only for circular orifice.

Depth to Bottom of Orifice m
Depth to Downstream Water Level m
Flow Discharge m³/s

Outputs

Coefficient of Discharge

Other Inputs

Small orifice only.

Coefficient of Discharge
Depth to Downstream Water Level m
Flow Discharge m³/s
Depth to Middle of Orifice m

Outputs

Area
Diameter m

Other Inputs

Small orifice only. Accuracy reduced if orifice size x 5 is less than water depth.

Coefficient of Discharge
Cross-sectional area of the tank
Initial Depth to Bottom of Orifice m
Final Depth to Bottom of Orifice m

Outputs

Time s

Sorry not possible. Please try another combination.