Calculator Inputs
Choose a method, enter known values, and calculate flow instantly. Optional density and viscosity fields add mass flow and Reynolds analysis.
Example Data Table
| Scenario | Method | Key Inputs | Estimated Flow |
|---|---|---|---|
| Cooling water line | Pipe diameter + velocity | Diameter: 100 mm, Velocity: 2.4 m/s | 0.01885 m³/s |
| Process channel | Velocity × area | Area: 0.012 m², Velocity: 1.8 m/s | 0.02160 m³/s |
| Orifice metering run | Orifice meter from ΔP | Pipe: 100 mm, Orifice: 60 mm, ΔP: 18 kPa | Depends on density and discharge coefficient |
Formula Used
1) Velocity × Area
Q = A × v
Where Q is volumetric flow, A is cross-sectional area, and v is average velocity.
2) Circular Pipe Area
A = πD² / 4
Use this when pipe diameter is known and velocity is available.
3) Mass Flow to Volumetric Flow
Q = ṁ / ρ
Where ṁ is mass flow and ρ is fluid density.
4) Orifice Meter Flow
Q = Cd × A2 × √(2ΔP / (ρ(1 − β⁴)))
Where Cd is discharge coefficient, A2 is orifice area, and β = d / D.
5) Reynolds Number
Re = ρvD / μ
This indicates whether the flow tends to be laminar, transitional, or turbulent.
How to Use This Calculator
- Choose the most suitable calculation method for your known data.
- Enter velocity, area, pipe diameter, mass flow, or differential pressure.
- Add density for mass flow output and differential pressure calculations.
- Add viscosity and hydraulic or pipe diameter for Reynolds number.
- Press Calculate Flow to show results below the header.
- Review converted units, flow regime, and the Plotly graph.
- Download the current output as CSV or PDF when needed.
Frequently Asked Questions
1. What does this flow measurement calculator estimate?
It estimates volumetric flow from velocity, area, pipe diameter, mass flow, or orifice differential pressure. It also converts units and can report Reynolds number when viscosity and diameter are supplied.
2. When should I use the pipe diameter and velocity method?
Use it when you know internal pipe diameter and average fluid velocity. The calculator first computes pipe area, then multiplies area by velocity to determine volumetric flow.
3. Why is density important for some methods?
Density is essential when converting mass flow to volumetric flow and when estimating differential-pressure flow through an orifice. Without density, those methods cannot produce reliable volumetric results.
4. What is Reynolds number used for here?
Reynolds number helps classify the flow regime. It compares inertial and viscous effects, indicating whether flow is likely laminar, transitional, or turbulent under the entered conditions.
5. Can this calculator be used for gases and liquids?
Yes. Enter appropriate density and viscosity values for the fluid. For compressible gas systems with large pressure changes, detailed compressibility corrections may still be required outside this tool.
6. What units does the result section provide?
The tool reports flow in m³/s, L/s, m³/h, and US gpm. It can also show mass flow, velocity, area, Reynolds number, and method-specific diagnostic values.
7. How accurate is the orifice meter method?
Accuracy depends on a realistic discharge coefficient, proper pipe dimensions, correct density, and stable differential pressure. Installation effects, tapping arrangement, and calibration can materially change real performance.
8. Why export results as CSV or PDF?
Exports make it easier to document calculations, share design checks, compare scenarios, and store engineering records without copying values manually from the screen.