Views: 215 Author: Site Editor Publish Time: 2025-05-19 Origin: Site
Maintaining contamination-free environments is vital in pharmaceutical, biotechnology, semiconductor, and electronics manufacturing. One of the unsung heroes in ensuring cleanliness in critical areas is the Pass Box. These devices allow materials to be transferred between cleanrooms of different classifications without risking contamination. This article will take a deep dive into the various types of pass boxes, their functions, features, and use cases, ensuring you fully understand their role in sterile and particulate-controlled environments.
A Pass Box is a critical component of cleanroom infrastructure designed to facilitate the transfer of materials without permitting air exchange between different classified areas. Its primary purpose is to minimize cross-contamination and maintain pressure differential integrity. Installed on partition walls between two areas, pass boxes are equipped with interlocking doors to ensure that only one door can be opened at a time, thereby limiting exposure.
They are frequently used in pharmaceutical labs, semiconductor facilities, hospitals, and food processing plants—anywhere cleanroom operations are essential. By acting as a buffer zone, pass boxes significantly reduce the frequency with which cleanroom personnel need to enter or exit, reducing foot traffic and contamination risk.
A Static Pass Box is the most basic type of pass box system. It is designed for transferring non-sensitive, non-biological materials between areas of equal cleanliness. There is no built-in air handling or HEPA/ULPA filtration in this model. The key feature lies in its simplicity—solid stainless steel construction, smooth surfaces, and a mechanical or electromagnetic interlocking system.
Static pass boxes are ideal for industries where the risk of particle contamination is low but control over material movement is still crucial. For example, they are commonly found in packaging or dry processing areas. Despite being unpowered, they are highly efficient in limiting human movement and preserving the cleanroom hierarchy.
Their advantages include:
Cost-effectiveness
Ease of installation
No need for electrical supply
Low maintenance requirements
However, due to the lack of filtration, they are not recommended for bio-sensitive environments.
The Dynamic Pass Box is a more advanced model designed for transferring materials between areas with differing cleanliness levels. This unit is equipped with HEPA or ULPA filters, a blower, and pre-filters, allowing it to deliver filtered air during the transfer process. These features make it ideal for high-risk environments like pharmaceuticals, microelectronics, or biotech labs.
HEPA Filtration: Capable of removing 99.97% of particles ≥0.3 microns.
UV Lamps (Optional): For biological decontamination.
Interlocking Doors: Electromagnetically controlled to prevent both doors from opening simultaneously.
SS304/SS316 Construction: Corrosion-resistant and easy to clean.
Dynamic pass boxes are widely used in Grade A/B cleanrooms, where product integrity is critical. These systems offer controlled airflows that create positive pressure inside the chamber, ensuring no contaminated air enters during material transfer. They are particularly beneficial in environments where aseptic conditions are a regulatory requirement.
A VHP Pass Box takes sterilization to another level by integrating Vaporized Hydrogen Peroxide (VHP) sterilization. These systems are often used in life sciences and biopharmaceutical applications where sterile transfer is mandatory. VHP technology kills bacteria, viruses, and fungi without leaving toxic residues.
The VHP system introduces vaporized hydrogen peroxide into the chamber, achieving high-level sterilization of surfaces and materials. After the cycle is complete, the system ensures the VHP is evacuated safely, maintaining safe oxygen levels before allowing door access.
| Feature | Description |
|---|---|
| Sterilant Used | Vaporized Hydrogen Peroxide (H₂O₂) |
| Filtration | HEPA/ULPA + VHP neutralization systems |
| Applications | Biotech, vaccine development, critical care |
| Compliance | GMP, FDA, ISO cleanroom standards |
Complete surface decontamination
Reduced downtime in material transfer
Compatible with highly regulated environments
This type of pass box is highly specialized and typically custom-designed to meet stringent compliance needs.
One of the critical components of any pass box is the door interlocking mechanism. The mechanism ensures that only one door can be opened at a time to maintain cleanroom integrity.
Mechanical interlocks are reliable and simple. They operate using internal gears or levers that physically prevent the second door from opening when one is already in use. This system is ideal for areas with stable environmental conditions and low risk of system failures.
Electromagnetic systems use powered magnets and control logic to lock and unlock doors. These can be integrated with access control systems, buzzer alarms, and sensors for added functionality and monitoring.
Both options serve their purpose well, and the selection typically depends on budget, operational complexity, and regulatory requirements.
Choosing the right pass box type isn’t a one-size-fits-all decision. Several factors must be considered, including:
Cleanroom Class Differences
Use dynamic pass boxes when transferring materials from a lower-grade to a higher-grade cleanroom.
Nature of Materials
For sterile goods or biological specimens, opt for a VHP pass box.
Budget Constraints
Static pass boxes offer economic advantages but limited functionality.
Compliance Requirements
Some industries require equipment to be GMP-compliant, influencing the choice.
| Pass Box Type | Best For | Filtration | Cost Level |
|---|---|---|---|
| Static | Dry material transfer, equal-grade rooms | None | Low |
| Dynamic | Pharmaceuticals, electronics | HEPA/ULPA | Medium |
| VHP | Sterile drug transfer, high containment | HEPA + VHP | High |
Always consult your cleanroom engineering team or validation experts before finalizing the selection.
Q1: Can pass boxes be customized?
Yes, most manufacturers offer customization in terms of size, materials, access control, filtration system, and UV sterilization features.
Q2: Are pass boxes GMP-compliant?
Dynamic and VHP pass boxes are typically designed to comply with GMP and FDA guidelines, while static models may not inherently meet those standards.
Q3: How often should a pass box be validated?
Validation frequency depends on your industry and usage intensity. Generally, HEPA filter integrity and airflow velocity should be tested every 6–12 months.
Q4: Can pass boxes be retrofitted into existing cleanrooms?
Yes, with proper wall cut-outs and air handling system adjustments, pass boxes can be integrated into existing setups.