Orifice Flow Rate Calculator
Calculation Results
Flow Rate (m³/hr):
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Flow Rate (Liters/min):
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Flow Rate (Gallons/min):
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Flow Velocity (m/s):
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About the Water Flow Rate Through an Orifice Calculator
This calculator determines the discharge flow rate of water (or similar low-viscosity fluids) passing through an orifice based on the diameter of the opening and the hydraulic head (pressure height) above it. It utilizes standard hydraulic principles derived from Bernoulli's equation and Torricelli's law.
How It Works
The flow rate is calculated using the following hydraulic formula:
Q = Cd × A × √(2 × g × h)
Where:
- Q = Flow rate (Discharge)
- Cd = Coefficient of Discharge
- A = Cross-sectional area of the orifice
- g = Acceleration due to gravity (9.81 m/s²)
- h = Head of liquid above the orifice center (meters)
Understanding the Inputs
To get an accurate result, ensure you are using the correct measurements:
- Orifice Diameter (mm): The internal diameter of the hole through which the water flows. Standard circular orifices are assumed.
- Liquid Head (m): The vertical distance from the center of the orifice to the surface of the liquid in the tank. This represents the pressure driving the flow.
- Discharge Coefficient (Cd): This dimensionless number accounts for energy losses and the contraction of the jet (vena contracta) as water exits the hole.
- 0.60 – 0.65: Typical for sharp-edged orifices.
- 0.80 – 0.82: Typical for short tube attachments.
- 0.95 – 0.98: Typical for smooth, well-rounded nozzles.
Common Applications
Calculating orifice flow is essential in various engineering and practical scenarios, including:
- Tank Draining: Estimating how fast a water tank will empty through a drain valve.
- Irrigation: Determining flow rates through sprinkler nozzles or drip emitters.
- Stormwater Management: designing restrictor plates for retention ponds to control outflow.
- Plumbing: Analyzing leaks or flow through damaged pipes.
Factors Affecting Accuracy
While this calculator provides a robust estimation, real-world flow can be influenced by fluid viscosity (if not water), the shape of the orifice edge, and whether the discharge is submerged or free-flowing. This tool assumes a free discharge into the atmosphere.