| Scenario | Points | Flow/Point (m^3/h) | Diversity | Leak (%) | Vacuum (kPa) | Pipe (m / mm) | Required Airflow (m^3/h) | Power (kW) |
|---|---|---|---|---|---|---|---|---|
| Concrete grinding extraction | 6 | 250 | 0.80 | 12 | 35 | 40 / 100 | ~1,512 | ~1.0–2.5 |
| Vacuum lifting, moderate pad seals | 3 | 180 | 0.90 | 8 | 60 | 25 / 80 | ~530 | ~1.0–3.5 |
| Light pneumatic conveying line | 4 | 300 | 0.70 | 15 | 50 | 55 / 125 | ~1,113 | ~2.0–6.0 |
- Select an application type, then click Apply Preset to load typical starting values.
- Enter the number of suction points and the flow required per point. Use a diversity factor if not all points run together.
- Add leakage and a safety factor to reflect site conditions and future expansion.
- Set vacuum level, pipe length, pipe diameter, and loss assumptions (friction factor and K).
- Click Calculate Vacuum Demand. The results appear above the form for quick review.
- Use Download CSV and Download PDF for reports and submittals.
Vacuum demand drivers on active construction sites
Vacuum systems are typically sized by airflow at each pick-up point, then adjusted for simultaneous use. A crew running grinders, scarifiers, or cleanup wands rarely operates every port at full demand. The diversity factor captures real utilization, preventing oversizing while maintaining capture velocity at tools. Leakage allowance accounts for hose couplers, worn seals, and quick-connect losses.
Using airflow, leakage, and safety margins for capacity
The calculator first determines diversified airflow, then adds leakage and a safety margin to produce a recommended capacity. Safety factor is practical for tool changes, filter loading, and future ports. For example data, six points at 250 m^3/h with 0.80 diversity yields 1,200 m^3/h diversified. With 12% leakage and 10% safety, capacity rises to about 1,478 m^3/h.
Estimating pipe losses for realistic pressure requirements
Airflow alone is not sufficient; the pump must overcome vacuum level plus distribution losses. The calculator uses Darcy friction with an equivalent length and a minor-loss coefficient K to represent bends, tees, and hoods. Larger diameters reduce velocity, lowering dynamic pressure and cutting losses. This improves noise, energy, and filter performance during long runs.
Power, energy, and efficiency assumptions
Pump power is computed from total pressure differential and volumetric flow, divided by efficiency. Efficiency should reflect motor, pump, and drive losses. If a measured value is unavailable, 60–75% is a reasonable planning range for many portable or skid systems. Daily energy helps compare electrical supply options and operating cost impacts.
Interpreting results for procurement and submittals
Use the required airflow and total pressure differential to shortlist equipment curves, then confirm the operating point with manufacturer data. If velocity is high or pipe losses exceed the vacuum setpoint, consider increasing main diameter or reducing fittings. Export the report to document assumptions, justify sizing, and align controls with site constraints.
1) What does “diversity factor” represent?
It represents the fraction of suction points expected to operate together. Use lower values when tools cycle or multiple crews share a system. It prevents oversizing while keeping realistic airflow for actual site usage.
2) How should I choose leakage allowance?
Start with 5–10% for tight, well-maintained hoses and fittings. Use 10–20% for older connections, many quick-couplers, or frequent reconfiguration. Higher leakage protects performance when seals degrade.
3) Is vacuum level the same as absolute pressure?
No. Vacuum level here is the pressure differential below atmospheric pressure. Equipment ratings may list either differential vacuum or absolute pressure. Convert consistently before comparing to pump or blower curves.
4) What is the minor loss coefficient K?
K is a simplified way to represent losses from bends, tees, inlets, and transitions. If your network has many fittings, increase K. If the run is mostly straight, reduce K and verify with field data.
5) Why does diameter affect power so much?
Diameter changes velocity. Higher velocity increases dynamic pressure, which increases friction and fitting losses. Reducing losses lowers required pressure differential, which directly lowers power for the same airflow.
6) How do I validate the power estimate?
Compare calculated airflow and pressure differential to manufacturer performance curves. Then confirm with a pitot traverse or inline flow measurement and a vacuum gauge at the pump inlet during typical operation.
7) When should I increase the safety factor?
Increase it when you expect more ports later, heavy filter loading, uncertain leakage, or variable tools. For stable, well-characterized setups, a smaller margin is acceptable after commissioning confirms performance.