Right-size airflow for dusty potting and sanding. Compare hood shapes, duct speeds, and pressure drops. Export a clear report for your shop setup decisions.
| Scenario | Hood opening | Capture velocity | Adjusted airflow | Duct diameter | Estimated static pressure |
|---|---|---|---|---|---|
| Potting bench hood | 24 in × 12 in | 200 fpm | ~480 CFM | 4 in | ~3.0 in.wg |
| Tool sanding hood | 18 in × 10 in | 300 fpm | ~563 CFM | 5 in | ~3.8 in.wg |
| Small circular pickup | 10 in diameter | 250 fpm | ~272 CFM | 4 in | ~2.6 in.wg |
Hood face area converts opening dimensions to square feet.
Base airflow (CFM) = Capture Velocity (fpm) × Hood Area (ft²).
Adjusted airflow = Base CFM × (1 + Leakage%) × (1 + Safety%).
Duct velocity = Adjusted CFM ÷ Duct Area (ft²).
Static pressure sums duct friction and component drops.
Fan power ≈ (CFM × Static Pressure) ÷ (6356 × Fan Efficiency).
Good collection starts at the hood. Capture velocity is the air speed at the opening that draws particles into the duct. Potting dust may need less pull than sanding fines, but both need consistent inward flow. Too low and dust escapes; too high and noise and power increase. Use the calculator to test velocities and add leakage and safety margins.
Airflow depends on opening area. A larger opening covers more work, yet it requires more airflow to maintain the same velocity. Rectangular faces suit benches; circular pickups suit small tools. Measure the clear opening, not the frame, and avoid grates that block flow. The calculator converts dimensions to area and multiplies by velocity to get base airflow.
After entry, friction and fittings create resistance. Long runs, many elbows, and flexible hose raise losses and reduce delivered airflow. Choose a duct size that keeps transport velocity high enough to carry dust, without driving pressure too high. Prefer smooth wall duct, gentle bends, and gradual transitions to limit turbulence. The calculator estimates duct speed, equivalent length, and friction loss so you can see where performance is being spent.
Filters and separators improve air quality, but they add pressure drop that grows as media loads. Use realistic drop values from product data and include a “dirty filter” scenario. A pre-separator can cut fine loading and extend service intervals. Regular cleaning and leak checks preserve airflow, often more than swapping to a bigger motor.
Treat adjusted airflow as the required fan delivery at the estimated static pressure. Verify your fan can meet both numbers, then refine the layout before buying upgrades. Save results, label each station, and retest after changing ducts or filters. Stable airflow keeps surfaces cleaner and makes indoor gardening work more comfortable. Pair airflow planning with simple housekeeping to reduce dust resuspension. Small improvements add up across every work session.
Start with 150–250 fpm for light potting dust and 250–400 fpm for sanding or fine powders. Increase if you see visible escape, and reduce if noise and power are excessive.
Real hoods leak at seams, tool openings, and moving workpieces. The allowances help you size airflow for everyday conditions rather than perfect lab sealing.
Many small systems aim around 3500–4500 fpm to keep particles moving. Lower speeds can settle dust in horizontal runs, while higher speeds increase friction and sound.
They increase effective length and turbulence, raising static pressure. Replacing flex with smooth duct and using long-radius bends often delivers more airflow than a larger fan.
Use the manufacturer’s pressure drop at your expected airflow. If possible, run a second check using a higher value to represent a loaded filter so you avoid undersizing.
Yes, for planning capture and transport airflow at dusty stations. It does not replace ventilation design for humidity, temperature, or chemical control, so confirm those needs separately.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.