Industrial Pass Box
An industrial pass box is a specialized piece of equipment used in controlled environments, such as cleanrooms, to transfer materials between areas of different cleanliness levels while minimizing contamination risks. It acts as a barrier to prevent cross-contamination, ensuring the integrity of sterile or controlled environments in industries like pharmaceuticals, biotechnology, electronics, food processing, and healthcare.
Definition
A pass box, also known as a transfer hatch, cleanroom pass-through, or sterile access system (SAS), is a sealed chamber with two interlocked doors (one on each side) that allows materials to be transferred between a cleanroom and a non-cleanroom area or between cleanrooms of different cleanliness levels. The interlocking mechanism ensures that only one door can be opened at a time, preventing direct airflow between the two areas and reducing the risk of airborne contaminants entering the cleaner environment. Pass boxes are typically constructed from stainless steel (e.g., SUS 304) for durability, ease of cleaning, and resistance to corrosion.
Key Features of a Pass Box:
- Interlocked Doors: Equipped with two doors (one on each side) that are mechanically or electronically interlocked, ensuring only one door can be open at a time to prevent cross-contamination.
- Construction: Typically made of stainless steel (e.g., SUS 304) for durability and ease of cleaning.
Types:
Static Pass Box: Used for transfers between areas of similar cleanliness levels (e.g., two cleanrooms). It lacks ventilation and relies on UV light and interlocks for contamination control.
Dynamic Pass Box: Used for transfers between areas of different cleanliness levels (e.g., non-cleanroom to cleanroom). It includes HEPA filters, a motor blower, and sometimes a differential pressure gauge to maintain air quality.
Functions:
- Contamination Control: Prevents airborne contaminants from entering the cleanroom by minimizing door openings and personnel traffic.
- Airflow Stability: Maintains stable air pressure and airflow within the cleanroom.
- Efficiency: Simplifies material transfer, reducing the need for gowning/ungowning procedures.
Applications:
- Pharmaceuticals: Transferring materials between compounding and filling areas.
- Electronics: Moving components between assembly and testing areas.
- Healthcare: Transferring sterile supplies between operating rooms and sterile processing.
- Food Processing: Moving products between preparation and packaging areas.
Working Principle:
- Materials are placed in the pass box through one door.
- The door is closed, and UV light may be activated to sterilize the items.
- In dynamic pass boxes, HEPA-filtered air removes dust particles.
- The opposite door is opened to retrieve the materials, ensuring no direct connection between the two areas.
Benefits:
- Reduces contamination risks.
- Saves time by streamlining material transfer.
- Enhances cleanroom hygiene with features like UV sterilization and HEPA filtration.
Maintenance Considerations
- Static Pass Box: Regular cleaning of surfaces and UV lamp replacement based on usage (tracked via hour meters).
- Dynamic Pass Box: Requires frequent maintenance of HEPA filters (replace every 6–12 months) and coarse filters (replace every 6 months). Monitor differential pressure gauges to detect filter issues.
- General: Ensure interlock systems and door seals are functional to maintain airtight conditions.
