Calculator Inputs
Example Data Table
| Case | Fluid | Flow | Density | Viscosity | Line ID | Allowable ΔP | Suggested Meter |
|---|---|---|---|---|---|---|---|
| Cooling Water Loop | Liquid | 120 m³/h | 998 kg/m³ | 0.001 Pa·s | 100 mm | 12 kPa | Magnetic |
| Compressed Air Header | Gas | 800 m³/h | 7.2 kg/m³ | 0.000018 Pa·s | 80 mm | 8 kPa | Ultrasonic |
| Steam Utility Branch | Steam | 950 kg/h equivalent* | 3.0 kg/m³ | 0.000013 Pa·s | 65 mm | 20 kPa | Vortex |
*For steam, enter the actual volumetric flow at operating conditions when using this calculator.
Formula Used
1) Flow continuity: Q = A × v
Where Q is volumetric flow rate, A is cross-sectional area, and v is average fluid velocity.
2) Pipe or meter area: A = πD² / 4
Where D is the internal diameter of the line or selected meter bore.
3) Required meter diameter: D = √(4Q / πv)
This estimates the bore needed to hit your chosen target velocity.
4) Reynolds number: Re = (ρ × v × D) / μ
Where ρ is density and μ is dynamic viscosity. Reynolds number helps judge flow regime and meter suitability.
5) Screening pressure drop: ΔP ≈ 0.5 × ρ × v² × K
Here K is a simplified meter factor used only for preliminary screening. Final pressure loss should always be confirmed with manufacturer data.
How to Use This Calculator
- Choose the fluid state and meter mode.
- Enter the operating flow rate and pick the correct flow unit.
- Input density, viscosity, and the actual line inside diameter.
- Set allowable pressure drop and your preferred velocity range.
- Add accuracy, turndown, conductivity, and solids information.
- Press the calculate button to see results above the form.
- Review velocity, Reynolds number, bore size, and ranked meter options.
- Download the CSV or PDF report for documentation.
FAQs
1. What does this calculator size?
It estimates a practical flow meter bore, line velocity, Reynolds number, pressure-drop screening value, and likely meter technologies for the entered process conditions.
2. Is the result enough for purchase?
No. It is a preliminary engineering tool. Final procurement should verify material compatibility, operating pressure, temperature limits, installation lengths, standards, and vendor curves.
3. Why is viscosity important?
Viscosity affects Reynolds number, pressure loss, and how well certain technologies perform. High-viscosity service can reduce turbine suitability and change the preferred meter choice.
4. Why can magnetic meters score poorly sometimes?
Magnetic meters need conductive liquids. They are not suitable for gases, steam, or non-conductive fluids, even when line size and velocity look acceptable.
5. What does turndown mean?
Turndown is the ratio between maximum and minimum measurable flow. Higher turndown generally improves flexibility when the process has wide flow variation.
6. Does the tool handle steam mass flow directly?
Not directly. Convert steam demand to volumetric flow at actual operating pressure and temperature before entering the value for better screening results.
7. What velocity should I target?
That depends on service and meter type. Many liquid systems use moderate velocities, while some gas and steam applications need different ranges for stable measurement.
8. Why is vendor pressure-drop data still needed?
Manufacturers use actual geometry, internals, and calibration data. Those details can shift pressure loss and sizing beyond the simplified screening factors used here.