This calculator treats gas flow factor as the packed-column and gas-handling F-factor: superficial gas velocity multiplied by the square root of gas density.
You can enter velocity and density directly, or derive them from flow, diameter, pressure, temperature, molecular weight, and compressibility factor.
Calculator Inputs
Example Data Table
| Case | Basis | Superficial Velocity (m/s) | Gas Density (kg/m³) | Gas Flow Factor | Reference Limit | Utilization |
|---|---|---|---|---|---|---|
| 1 | Direct inputs | 1.8000 | 1.4500 | 2.1675 | 2.5000 | 86.70% |
| 2 | Flow and state properties | 1.5915 | 2.8268 | 2.6759 | 2.5000 | 107.04% |
| 3 | Flow and state properties | 1.4260 | 1.6690 | 1.8423 | 2.5000 | 73.69% |
Example 2 assumes 0.45 m³/s, 0.60 m diameter, 250 kPa abs, 35°C, molecular weight 28.97, and Z = 1.00.
Formula Used
Variable definitions
A = flow area, D = diameter, u = superficial gas velocity, Q = actual volumetric flow rate.
ρ = gas density, P = absolute pressure, M = molecular weight, Z = compressibility factor, R = universal gas constant, T = absolute temperature.
F-factor units in SI are m/s·√(kg/m³), numerically equivalent to Pa0.5.
How to Use This Calculator
- Choose whether you want to enter superficial velocity directly or derive it from actual flow rate and diameter.
- Choose whether you want to enter gas density directly or estimate it from pressure, temperature, molecular weight, and compressibility factor.
- Enter a reference F-factor limit when you want a utilization percentage and design margin.
- Click Calculate Gas Flow Factor to show the result above the form.
- Use the export buttons to save the current result as CSV or PDF for design notes or reports.
FAQs
1) What is the gas flow factor?
It is an intensity parameter for gas handling. In packed equipment, it is commonly defined as superficial gas velocity multiplied by the square root of gas density.
2) Why does the calculator use superficial velocity?
Superficial velocity is based on empty cross-sectional area. It gives a consistent comparison basis for columns, ducts, internals, and scale-up studies.
3) When should I use direct density input?
Use direct density when you already know gas density from simulation, plant historian data, gas-property software, or laboratory measurements under operating conditions.
4) Why must pressure be absolute?
Density equations require absolute pressure. Gauge pressure ignores atmospheric pressure and would underpredict density, mass flux, and gas flow factor.
5) What does the compressibility factor do?
It adjusts ideal-gas density for real-gas behavior. A value near 1.0 suits many light-duty estimates, but process-specific data is better for critical design work.
6) Is one F-factor limit valid for every service?
No. Acceptable limits depend on packing style, liquid loading, pressure, foaming tendency, flood margin, efficiency target, and vendor recommendations.
7) What does utilization percentage tell me?
It compares the calculated F-factor with your selected reference limit. Values near or above 100% suggest the operating point deserves closer design review.
8) Can I use this for final equipment sizing?
It is excellent for screening, comparisons, and quick engineering checks. Final sizing should still be validated with detailed hydraulic methods and vendor data.