Analyze cleanroom ventilation, volume, and target turnover. Calculate required airflow, timing, and margin with clarity. Improve airflow planning using practical inputs and visual results.
This chart compares supply, recirculation, effective airflow, and required airflow for the target turnover rate.
| Metric | Formula | Meaning |
|---|---|---|
| Room Volume | Volume = Length × Width × Height | Computes the room size used in airflow turnover calculations. |
| Gross Airflow | Gross Airflow = Supply + Recirculation | Combines the primary supply flow and the recirculated flow. |
| Effective Airflow | Effective = Gross × Utilization × Safety | Adjusts gross flow for practical distribution and design margin. |
| Air Changes per Hour | ACH = Effective Airflow ÷ Room Volume | Shows how many full room air replacements occur hourly. |
| Required Airflow | Required = Target ACH × Room Volume | Shows the minimum flow needed to hit the target. |
| Time per Air Change | Minutes per Change = 60 ÷ ACH | Estimates how long one full air replacement takes. |
| Purge Time | Time = [−ln(1 − removal fraction) ÷ ACH] × 60 | Estimates time for contaminant removal milestones like 99%. |
For engineering review, use this calculator alongside project requirements, room classification goals, pressure strategy, and applicable validation procedures.
| Length | Width | Height | Supply | Recirculation | Exhaust | Target ACH | Calculated ACH | Status |
|---|---|---|---|---|---|---|---|---|
| 8 m | 6 m | 3 m | 5400 m³/h | 2400 m³/h | 5000 m³/h | 50 | 54.03 | Meets target |
| 10 m | 7 m | 3.2 m | 6200 m³/h | 2800 m³/h | 5700 m³/h | 40 | 37.50 | Below target |
| 24 ft | 16 ft | 10 ft | 3500 CFM | 1200 CFM | 3000 CFM | 45 | 124.74 | Exceeds target |
These examples illustrate how room size, total airflow, and target turnover interact. Always verify final cleanroom criteria with your design basis.
Air changes per hour show how many times the room’s total air volume is replaced within one hour. Higher values usually support faster dilution, stronger cleanliness control, and better recovery after contamination events.
ACH is based on airflow divided by room volume. A larger room needs more airflow to achieve the same turnover rate. Small volume changes can noticeably affect the calculated performance result.
Yes, when recirculated air is part of the effective cleanroom air delivery strategy. Including it helps reflect total treated airflow moving through the space, not only outside supply air.
Utilization factor adjusts theoretical airflow to reflect real distribution performance. It helps account for imperfect mixing, layout effects, diffuser arrangement, and other practical limitations inside the room.
A safety factor adds design margin. It can help cover uncertainty, future process demand, airflow losses, or conservative engineering practice during early sizing and planning.
No. This tool supports planning and quick engineering checks. Final compliance should rely on project specifications, classification requirements, measured performance, balancing data, and validation testing.
Purge time estimates how quickly the room can reduce airborne contamination levels under ideal assumptions. It is useful for comparing recovery performance, but actual results depend on flow pattern and contamination sources.
Choose the unit that matches your design data. This calculator accepts m³/h, CFM, and L/s, then converts the value internally so results stay consistent.
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.