Orifice Flow Calculator
Find flow through an orifice under a head of fluid.
Find the flow of liquid escaping through a small opening under gravity.
How the Math Works
The Orifice Flow Calculator uses the formula Q = Cd·A·√(2·g·h) to determine fluid flow rate (Q) through an orifice. Here, Cd is the discharge coefficient (accounting for energy losses), A is the orifice area (πr²), g is gravitational acceleration (9.81 m/s²), and h is the fluid head height. The square root term √(2gh) derives from Torricelli’s law, representing fluid velocity under gravity. Multiplying these factors gives the volumetric flow rate, enabling precise calculations for engineering and industrial applications.
Practical Applications
To apply this formula, first measure the orifice diameter to calculate area (A = π*(d/2)²). Determine the vertical fluid height (h) above the orifice and obtain the appropriate Cd value from experimental tables or manufacturer data (typically 0.6–0.8 for sharp-edged orifices). Input these values into the calculator to predict flow rate, which helps size pipes, pumps, or valves and ensure system efficiency in water treatment, HVAC, or chemical processing systems.
Day-to-Day Use
This calculation helps in everyday scenarios like designing household plumbing systems, optimizing garden irrigation setups, or understanding flow in soda bottles and showerheads. It also explains why certain drain sizes work better for bathtubs or sinks, preventing backups by matching flow capacity to expected usage. By grasping this principle, homeowners can make informed decisions about water usage, maintenance, and even energy savings in appliances.
Worked example
Cd 0.62, A 0.001 m², head 2 m → about 0.00388 m³/s.
FAQ
Why √h?
Exit velocity is √(2gh), so flow scales with the square root of head.