HVAC Design for Clean Rooms - Hospitals & Pharma

 HVAC Design for Clean Rooms - Hospitals & Pharma

1. Clean Room Classifications (ISO & GMP) 

Classification Max. Particles ≥0.5µm / m³ Typical Use

ISO 5/ Class 100 3,520 OT, IV Room ISO 7/ Class 10,000 352,000 Compounding Area

ISO 8/ Class 100,000 3,520,000 Packing Area

2. Air Changes Per Hour (ACH)

Room Type Recommended ACH

Operation Theater (OT) 20-25

ICU/NICU 15-20

Cleanrooms ISO 7 60-90

Cleanrooms ISO 8 15-20

Example:

Room Volume = 5 m x 5 m x 3 m = 75 m³

ACH = 25 Airflow = (25 x 75)/60 = 31.25 CMM ≈ 1100 CFM

3. HEPA Filter Design

HEPA Efficiency: ≥99.97% @ 0.3µm

1 HEPA filter (24"x 24") handles ~500 CFM

OT needing 1000 CFM Use 2 filters

4. Room Pressure Differential

Area Type Pressure Difference

OT vs Corridor +10 to +15 Pa

ICU vs Corridor +5 to +10 Pa

Isolation Room -10 to-15 Pa

5. Laminar Airflow (LAF)

Velocity: 90 ± 20 ft/min (0.45 ± 0.05 m/s)

Area: ~9 ft x 6 ft above OT table

6. Humidity & Temperature Control

Area Temp (°C) RH (%)

OT 21-24 50-60

ICU / Patient Room 23-26 30-60

Pharma Clean room 20-22 45-55

7. Exhaust Systems

Negative pressure rooms require 100% exhaust

Use bag-in bag-out filters for hazardous exhausts

8. Validation Parameters

Air velocity test

Smoke pattern ( laminarity )

Particle count

HEPA integrity test

Example: Small OT Room (ISO 7 / GMP Grade B)

Parameter Value

Room Volume 6 m x 5 m x 3 m = 90 m³

ACH 25 Airflow = 1325 CFM

HEPA Filters 3 (500 CFM each)

Pressure +15 Pa

Temp/RH 22°C / 55%