Air Shower: Principles and Functions in Cleanroom Environments

Essential Equipment for Contamination Control

I. Introduction to Air Showers

Air showers are specialized self-contained chambers installed at cleanroom entrances to remove particulate contaminants from personnel or objects before they enter the controlled environment. These contamination control devices play a critical role in pharmaceutical, semiconductor, biotechnology, and other industries requiring stringent cleanliness standards.

II. Working Principle

Air showers operate on a simple but effective principle:

1. High-velocity HEPA or ULPA filtered air jets (typically 20-25 m/s) are directed from multiple nozzles
2. The turbulent airflow creates a scrubbing action that dislodges particles from surfaces
3. Contaminated air is drawn through floor grilles and recirculated through the filtration system
4. The cycle continues for a preset duration (usually 15-30 seconds)

III. Key Components

Modern air showers consist of several essential components:

• Stainless steel or powder-coated steel enclosure
• High-efficiency particulate air (HEPA) filters (99.99% @ 0.3μm)
• High-velocity air nozzles (typically 12-36 nozzles depending on size)
• Interlocking door system (prevents both doors opening simultaneously)
• Control panel with programmable timer
• Emergency stop button and safety features

IV. Primary Functions

Air showers serve multiple critical functions in contamination control:

1. Particle Removal: Effectively removes surface particles from personnel and materials
2. Air Barrier: Creates positive pressure barrier preventing unfiltered air entry
3. Personnel Awareness: Reinforces cleanroom protocol compliance
4. Contamination Reduction: Can remove up to 95% of surface particles

V. Applications

Air showers are essential in various industries including:

• Pharmaceutical manufacturing (GMP compliance)
• Microelectronics and semiconductor fabrication
• Biotechnology research facilities
• Medical device manufacturing
• Aerospace component production
• Hospital operating theaters

VI. Selection Considerations

When specifying an air shower, consider these factors:

1. Required cleanliness class (ISO 14644-1 standards)
2. Anticipated personnel/material traffic
3. Available space and installation requirements
4. Material compatibility (stainless steel for corrosive environments)
5. Additional features like air ionization or static control