Air Shower Pass Box: Structural Features and Working Principle
创建于06.19
1. Structural Features
The air shower pass box consists of several major components, including the cabinet, centrifugal fan, primary & HEPA filters, and control switches.
2. Working Principle
l Ambient air passes through the primary filter and is pressurized into the plenum chamber by the centrifugal fan.
l The air then undergoes HEPA filtration and is discharged from the top diffuser plate as clean airflow.
l The clean air continuously mixes with and dilutes the ambient air, achieving a purification effect.
Detailed Technical Description
I. Structural Features
Cabinet System
l Constructed from 304 stainless steel or powder-coated steel plates, with seamless welding for airtightness.
l Dual-door interlock mechanism (mechanical/electronic) to prevent cross-contamination.
l Built-in tempered glass viewing window, with optional UV sterilization lamp.
l Removable stainless steel dust collection tray at the bottom.
Air Handling System
l Centrifugal fan: Typically a multi-wing type (airflow 1200-2000 m³/h).
l Filtration system:Primary filter (G4 grade): Captures particles ≥5μm, protecting the HEPA filter.
l HEPA filter (H13-H14): 99.97-99.99% filtration efficiency @0.3μm.
l Plenum chamber: Designed for uniform air distribution.
Control System
l Microprocessor-based control panel.
l Adjustable air shower time (10-999 seconds).
l Differential pressure sensor for filter status monitoring.
l Photoelectric sensor for automatic activation.
Additional Configurations
l V-shaped airflow nozzles (wind speed ≥20 m/s).
l Built-in sterilization lamp (UVC or ozone optional).
l Conveyor belt system (for large pass-through units).
II. Working Principle
Air Purification Cycle
l Pre-filtration: Ambient air passes through the primary filter to remove large particles.
l Pressurization: The centrifugal fan forces air into the plenum chamber.
l HEPA filtration: Air is purified to ISO Class 5 (Class 100) cleanliness.
l Turbulent cleaning: The top diffuser plate creates uniform vertical airflow (20-25 m/s).
l Particle removal: High-speed airflow removes ≥99.5% of particles ≥0.5μm from surfaces.
Pressure Differential Maintenance
l Maintains positive pressure (+15Pa or higher) inside the chamber.
l Acts as an airlock to protect cleanroom pressure integrity.
Dynamic Purification Process
l Particle concentration decays exponentially: C = C₀e^(-nt) (where *n* = air change rate).
III. Example Technical Parameters
Parameter | Specification |
Cleanliness | ISO Class 5 (Class 100) |
Airflow Speed | ≥20 m/s |
Noise Level | ≤65 dB |
Power Supply | 380V/50Hz or 220V/50Hz |
Sterilization Rate | ≥99.9% (with UVC) |
IV. Application Features
l Simultaneous material transfer and surface decontamination.
l Reduces particle introduction by 90% compared to standard pass boxes.
l Suitable for Grade B → Grade A cleanroom transitions.
l Complies with GMP dynamic cleanliness requirements.
This equipment utilizes forced convection cleaning to enable real-time purification during material transfer, overcoming the limitations of traditional pass boxes that rely solely on static self-cleaning. It is a standard configuration in modern cleanroom logistics systems.
Frequently Asked Questions (FAQ)
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