Which area terms should stay separate?
Gross opening, free area and effective airflow area are not interchangeable. Record the supplier's product, configuration and test basis.
| Term | Meaning | Use |
|---|---|---|
| Gross area | Overall opening size | Layout |
| Free area | Unobstructed fraction | Preliminary airflow calculation |
| Pressure loss | Resistance at a flow | Ventilation review |
| Effective result | Installed system outcome | Qualified design |
Who approves the ventilation basis?
The responsible mechanical engineer and equipment supplier approve the selected louver, airflow and pressure-loss basis.
Sources: Cummins: Application Manual: Liquid Cooled Generator Sets, ventilation chapter
Common questions
What else should the bid team know?
Does free area define louver performance?
No. Pressure loss, weather protection, noise and installation also matter.
Can free area be guessed from a picture?
No. Use supplier data for the exact louver configuration.
Primary sources
- Application Manual: Liquid Cooled Generator Sets, ventilation chapterCummins
- Ambient Capability of Enclosed Generator SetsCaterpillar
- ISO 8528-10:2022, Measurement of airborne noiseInternational Organization for Standardization
- ISO 3744:2025, Determination of sound power levelsInternational Organization for Standardization