Pass Box
A Pass Box (also called a transfer hatch or material airlock) is a small enclosed chamber installed in a cleanroom wall that allows materials to move between areas of different cleanliness without people passing through. Its interlocked doors ensure only one side opens at a time, limiting direct air exchange and cross-contamination.
How Pass Box works
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Place the item inside through the “dirty” or lower-cleanliness side.
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Close and lock that door.
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Open the opposite door from the controlled area and remove the item.
Because the two doors cannot open simultaneously, the pass box acts as a barrier between the rooms.
Main Types
| Type | Features | Typical use |
|---|---|---|
| Static pass box | Interlocked doors only; may include UV lamp; no forced airflow | Transfer between areas of similar cleanliness |
| Dynamic pass box | HEPA/ULPA-filtered air, blower, sometimes pressure controls and UV sterilization | Transfer into higher-grade cleanrooms or between different cleanliness classes |
| Semi-active pass box | Mild HEPA-filtered airflow, but less elaborate than dynamic units | Moderate contamination-control needs |
Where Pass Boxis used
Pass boxes are common in pharmaceutical plants, hospitals and modular operating theatres, laboratories, semiconductor/electronics facilities, and food-processing cleanrooms. They reduce personnel traffic, preserve pressure and airflow conditions, and help maintain the cleanroom’s ISO classification.