Why cleanroom units differ
Air handling units for cleanrooms are the core of a contamination-controlled micro-environment and differ greatly from comfort units. They must meet far stricter performance demands driven by the process.
Six defining characteristics
- Large airflow: cleanliness is maintained by recirculating air, with air changes often ten to several hundred times per hour, demanding a strong aluminium or steel frame and thick panels.
- High fan static pressure: three filter stages add roughly 700โ800 Pa of resistance, so backward-curved or plenum fans are used.
- Precise temperature and humidity: cooling, heating, humidifying and dehumidifying sections are controlled by PI or PID loops.
- Strict positive or negative pressure control: positive pressure for general use, negative pressure where toxic or hazardous substances exist.
- A robust filtration train: pre, medium and HEPA filters with airtight sealing to avoid any leakage.
- Widespread use of variable-frequency drives, sized on final filter resistance to cut energy use.
Selection
Choosing the right unit means balancing these traits against process requirements, energy goals and lifetime cost.