Gowning Areas

Gowning areas serve as critical transition zones between general environments and cleanrooms, providing space for personnel to don protective garments while preventing contamination transfer. Proper HVAC design ensures these airlocks effectively protect cleanroom integrity.

Gowning Area Functions

Contamination Control

Gowning rooms minimize particle introduction by:

• Providing transition between cleanliness levels
• Allowing personnel to don clean garments
• Establishing pressure barriers
• Capturing contamination before cleanroom entry
• Supporting garment storage

Zone Classification

Gowning areas typically maintain intermediate cleanliness:

Pressure Relationships

Cascade Design

Establish pressure gradient from cleanest to dirtiest:

Cleanroom → Gowning → Corridor/Anteroom → General
(Highest)    (Mid)         (Low)          (Lowest)

Typical Pressure Differentials:

• Cleanroom to gowning: +0.03 to +0.05" w.g.
• Gowning to anteroom: +0.02 to +0.03" w.g.
• Anteroom to corridor: +0.01 to +0.02" w.g.

Airlock Configuration

Single-Stage Gowning:

• One room between corridor and cleanroom
• Suitable for ISO Class 7-8 cleanrooms
• Lower construction cost

Two-Stage Gowning:

• Anteroom + gowning room
• Required for ISO Class 5-6 cleanrooms
• Better contamination control
• Personnel flow management

Door Interlocks

Prevent simultaneous door opening:

• Magnetic locks with indicators
• PLC-controlled interlocking
• Emergency override capability
• Visual status indication

Airflow Design

Air Change Rates

Air Distribution

Ceiling Supply:

• Non-unidirectional for most gowning rooms
• HEPA filtered terminal units
• 2-4 ft/s face velocity at diffusers

Low-Level Return:

• Located near floor level
• Captures particles generated during gowning
• Multiple locations for uniform flow

Special Considerations

Bench Placement:

• Dirty side / clean side separation
• Airflow direction supports separation
• Particle control at seated position

Mirror Locations:

• Full-length for garment inspection
• Lighting for visual verification
• Away from supply air paths

Temperature and Humidity

Comfort Requirements

Gowning involves physical activity and garment insulation:

Temperature: 66-72°F (19-22°C)

• Lower than office due to gowning activity
• Account for garment insulation

Relative Humidity: 30-60%

• Static control (minimum 30%)
• Comfort (maximum 60%)
• Material compatibility

Pharmaceutical Requirements

GMP environments may specify:

• 68°F ± 2°F during gowning operations
• 45% ± 5% RH
• Continuous monitoring and alarming

Filtration Requirements

Supply Air Filtration

Terminal HEPA:

• Required for ISO Class 7 and cleaner
• 99.99% minimum efficiency
• Ceiling-mounted terminal units

Pre-filtration:

• MERV 14-16 at AHU
• Extends HEPA life
• Reduces maintenance frequency

Return Air Considerations

• Filter return air before recirculation
• MERV 8-13 typical
• Prevents cross-contamination

Garment Storage

Clean Garment Storage

HVAC considerations for storage:

• Positive pressure relative to gowning
• HEPA-filtered supply
• Minimize dust accumulation
• Temperature/humidity control

Soiled Garment Collection

• Negative pressure or neutral
• Adequate exhaust
• Sealed containers
• Separate from clean garments

Monitoring and Control

Environmental Monitoring

Continuous Monitoring:

• Differential pressure (all rooms)
• Temperature and humidity
• Airflow verification

Periodic Testing:

• Particle counts (classification)
• HEPA filter integrity
• Air balance verification

Alarm Systems

Critical parameter alarming:

• Pressure differential deviation
• Door position status
• Temperature/humidity excursions
• HEPA filter loading

Design Considerations

Personnel Flow

Design to support logical gowning sequence:

1. Enter anteroom, remove street clothes
2. Cross to gowning room
3. Don cleanroom garments
4. Inspect in mirror
5. Enter cleanroom

Traffic Patterns

• Minimize backtracking
• Separate entry and exit when possible
• Accommodate peak traffic
• Emergency egress provisions

Sizing

Allow adequate space:

• Minimum 50 ft² per gowning station
• Clear floor area for movement
• Storage for garment supplies
• Mirror and inspection area

Properly designed gowning area HVAC systems support personnel transition while maintaining the pressure cascades and air cleanliness essential for cleanroom contamination control.

Sections