Pressure Drop to Flow Rate Calculator
Calculate volumetric flow rate based on differential pressure and pipe geometry
Estimated Flow Rate
Understanding Pressure Drop and Flow Rate
In fluid dynamics, the relationship between pressure drop ($\Delta P$) and flow rate ($Q$) is fundamental for sizing pumps, pipes, and control valves. When a fluid passes through a restriction (like an orifice plate, a valve, or a narrow section of pipe), its velocity increases, and its static pressure decreases. This calculator uses the Bernoulli principle and the flow equation to estimate how much fluid is moving through the system based on that observed pressure loss.
The Calculation Formula
The calculator uses the standard discharge equation for flow through an orifice or restriction:
Where:
- Q: Volumetric Flow Rate ($m^3/s$)
- Cd: Discharge Coefficient (accounts for energy losses and flow contraction)
- A: Cross-sectional area of the opening ($\pi \cdot r^2$)
- ΔP: Pressure Drop (Difference between upstream and downstream pressure)
- ρ (Rho): Density of the fluid
Practical Examples
| Scenario | ΔP (Bar) | Diameter (mm) | Result (m³/h) |
|---|---|---|---|
| Small Water Pipe | 0.5 bar | 25 mm | ~10.8 m³/h |
| Industrial Main | 2.0 bar | 100 mm | ~345.2 m³/h |
Key Factors Influencing Flow
1. Pressure Differential: Flow rate is proportional to the square root of the pressure drop. To double the flow rate, you typically need to quadruple the pressure drop.
2. Pipe Diameter: Flow rate is highly sensitive to the diameter because the area increases with the square of the radius. Small changes in diameter lead to massive changes in flow capacity.
3. Fluid Density: Heavier fluids (like oils or mud) require more pressure to achieve the same flow rate as lighter fluids (like water or chemicals).
4. Discharge Coefficient (Cd): This value varies by the shape of the restriction. A smooth nozzle might have a Cd of 0.98, while a sharp-edged orifice plate typically falls around 0.60 to 0.65.