Calculator Inputs
Example Data Table
| Bore Diameter | Pressure Drop | Length | Fluid | Density | Viscosity | Suggested Use |
|---|---|---|---|---|---|---|
| 8 mm | 1.5 bar | 5 m | Water | 998.2 kg/m³ | 0.001 Pa·s | Small bench hose estimate |
| 12 mm | 2 bar | 10 m | Water | 998.2 kg/m³ | 0.001 Pa·s | General laboratory transfer |
| 25 mm | 3 bar | 30 m | Light oil | 850 kg/m³ | 0.045 Pa·s | Viscous process check |
Formula Used
Pipe area: A = πD² / 4
Volumetric flow: Q = A × v
Mass flow: ṁ = ρQ
Reynolds number: Re = ρvD / μ
Pressure balance: ΔP = (fL / D + K) × ρv² / 2
Laminar friction factor: f = 64 / Re
Turbulent estimate: f = 0.25 / [log10(ε / 3.7D + 5.74 / Re⁰·⁹)]²
The calculator iterates velocity because friction factor depends on Reynolds number, and Reynolds number depends on velocity.
How To Use This Calculator
- Enter the hose inside bore diameter in millimetres.
- Enter the pressure drop available across the hose.
- Enter the hose length in metres.
- Set density and viscosity for the selected fluid.
- Add roughness and minor loss values if known.
- Adjust the discharge coefficient for fittings or practical losses.
- Enter a sample volume to estimate filling time.
- Press the calculate button and review results above the form.
- Use the CSV or PDF button to save the report.
Advanced Flow Insight
Advanced Flow Insight
A Copely flow rate calculator helps estimate how much fluid moves through a hose or tube during a set time. The main physics idea is simple. Pressure pushes the fluid. Diameter controls area. Length adds friction. Fluid density and viscosity change resistance. This version joins these factors in one practical worksheet.
Why This Calculator Helps
Flow work often starts with incomplete notes. A user may know bore size, working pressure, and hose length, but still need velocity, litres per minute, gallons per minute, and Reynolds number. Manual calculation can become slow because friction factor depends on velocity. The calculator repeats the estimate until the velocity and friction factor agree. That makes the result more useful than a single fixed coefficient.
Physics Behind The Estimate
The tool combines continuity, pressure loss, and Reynolds number. Continuity converts velocity into volume flow. The Darcy style pressure balance estimates velocity from available pressure, hose length, minor losses, and friction. The Reynolds number checks whether the flow is laminar, transitional, or turbulent. Laminar flow is smooth and predictable. Turbulent flow has stronger mixing and higher loss. Transitional flow should be treated carefully because small changes can shift behavior.
Best Practice Notes
Use measured inside bore diameter whenever possible. A small diameter error can create a large flow error. Enter pressure drop across the hose, not total pump rating, when that value is known. Add minor loss values for bends, valves, quick connectors, filters, and nozzles. Use realistic density and viscosity for the fluid temperature. Water values are acceptable for quick training examples, but oil, air, syrup, and process fluids need their own properties.
How To Read Results
The litre per minute value is useful for field checks. The cubic metre per second value supports physics reports. Velocity helps judge erosion risk and noise. Reynolds number explains the regime. Mass flow rate helps when density matters. The fill time estimate shows how long a selected volume may take. Results are engineering estimates, not certification data. For safety systems, medical devices, or regulated testing, compare the output with calibrated instruments and approved procedures. Save exported files with input notes so later reviews can trace assumptions, compare trials, and improve the next setup with confidence.
FAQs
What does this calculator estimate?
It estimates average volumetric flow through a hose or tube using bore diameter, pressure drop, length, fluid density, viscosity, roughness, and minor losses.
Can I use it for air?
You can use it for simple training estimates, but compressible gas flow needs extra care. Use calibrated tools for final air system design.
Why does diameter matter so much?
Diameter controls cross-sectional area and friction behavior. Small bore changes can strongly change velocity, Reynolds number, and final flow rate.
What is pressure drop?
Pressure drop is the pressure available across the hose section. It is not always the same as the pump rating or supply pressure.
What is the minor loss coefficient?
It represents extra losses from fittings, bends, valves, filters, entrances, exits, and connectors. Higher values reduce predicted flow.
What does Reynolds number show?
Reynolds number indicates flow regime. Low values suggest laminar flow. High values suggest turbulent flow with stronger mixing and friction.
Why is viscosity needed?
Viscosity measures fluid resistance to motion. Thicker fluids usually flow slower through the same hose under the same pressure drop.
Are the results exact?
No. They are engineering estimates. Real flow can change with temperature, hose shape, fittings, pulsation, leaks, and measurement conditions.