Room Pressurization Tests
Room pressurization tests measure and verify the pressure differential between adjacent spaces to ensure controlled airflow. These tests are critical in cleanrooms, hospitals, laboratories, pharmaceutical manufacturing, and biosafety containment areas, where maintaining the correct pressure prevents cross-contamination.

1. Purpose of Room Pressurization Testing
Prevents contamination by controlling airflow direction.
Ensures compliance with industry standards (ISO 14644, ASHRAE, WHO, USP 797/800).
Verifies HVAC system performance in maintaining pressure differentials.
Maintains safety in biosafety labs and hazardous material storage areas.

2. Types of Room Pressurization
a. Positive Pressure Rooms (Higher pressure than adjacent areas)
Used in cleanrooms, operating rooms, pharmaceutical manufacturing.
Prevents contaminants from entering the room.
Air flows out when a door is opened.
b. Negative Pressure Rooms (Lower pressure than adjacent areas)
Used in isolation rooms, biosafety labs, hazardous material storage.
Prevents hazardous particles from escaping.
Air flows in when a door is opened.

3. Room Pressurization Test Methods
a. Differential Pressure Measurement (Most Common)
Uses digital manometers or pressure sensors to measure pressure differences between rooms.
Readings should meet design specifications (e.g., +10 to +15 Pa for positive pressure rooms, -30 Pa for negative pressure rooms).
b. Smoke Visualization Test
Uses smoke wands or fog generators to observe airflow direction.
Confirms if air moves into or out of the controlled space.
Commonly used as a quick validation method.
c. Anemometer-Based Airflow Measurement
Uses hot-wire anemometers to measure air velocity at door gaps or pass-throughs.
Ensures proper airflow direction is maintained.
d. Tracer Gas Testing
Introduces a tracer gas (CO₂, SF₆) in one room and measures its presence in adjacent areas.
Used in critical contamination control environments.

4. Pass/Fail Criteria for Room Pressurization
Room Type
Recommended Differential Pressure
Positive Pressure (Cleanroom, OR)
+10 to +15 Pa (higher than surroundings)
Negative Pressure (Isolation, BSL-3)
-30 to -50 Pa (lower than surroundings)
Biosafety Level 4 (BSL-4)
-100 Pa (or per design specs)
Pharmaceutical Compounding (USP 797/800)
+0.02 to +0.05 in. WC (for sterile areas)
Pass: Pressure differentials meet design criteria.
Fail: Pressure differentials are too low or reversed → requires HVAC adjustments.

5. Corrective Actions for Failed Pressurization Tests
Check HVAC system balance (adjust air supply and exhaust rates).
Seal leaks in doors, walls, or HVAC ducting.
Ensure HEPA filters are properly installed (for cleanrooms).
Reconfigure airlocks or entryways if necessary.

6. Applications of Room Pressurization Testing
Cleanrooms (ISO 14644, GMP, FDA): Ensures contamination control.
Hospitals (Isolation Rooms, ORs, Pharmacies): Prevents infection spread.
Biosafety Labs (BSL-3, BSL-4): Prevents hazardous material escape.
Pharmaceutical & Semiconductor Facilities: Maintains air purity.
Would you like a detailed test procedure or assistance with interpreting results?