Cleanroom pressurization, also known as positive pressure control, is a crucial aspect of maintaining a clean and controlled environment in cleanrooms.

Importance of Cleanroom Pressurization

Contamination control

• By maintaining a higher pressure inside the cleanroom compared to adjacent areas, air flows outward from the cleanroom. This prevents the ingress of contaminated air from surrounding environments, reducing the risk of particle and microbial contamination.
• For example, in pharmaceutical manufacturing cleanrooms, pressurization helps ensure that no outside contaminants enter the production area, safeguarding the purity of drugs.

Protection of sensitive processes

Some cleanroom processes are highly sensitive to even trace amounts of contaminants. Pressurized cleanrooms provide a stable and controlled environment that protects these processes from external influences.

In semiconductor fabrication, cleanroom pressurization is essential to prevent dust and airborne particles from damaging delicate electronic components.

Methods of Achieving Cleanroom Pressurization

Supply and exhaust air systems

• A carefully designed air supply and exhaust system is key to maintaining proper pressurization. Clean air is continuously supplied to the cleanroom at a controlled rate, while exhaust air is removed to maintain the desired pressure differential.
• The volume and velocity of the supply and exhaust air can be adjusted to achieve the required pressurization level.

Air filters

High-efficiency particulate air (HEPA) filters and ultra-low penetration air (ULPA) filters are used to remove particles from the supply air. This helps maintain a clean air environment and contributes to pressurization by reducing the amount of contaminants that could enter the cleanroom through leaks.

Dampers and controls

Dampers are installed in the air supply and exhaust ducts to regulate the flow of air and maintain the desired pressure differential. Automated control systems monitor the pressure and adjust the dampers as needed.

Monitoring and Maintenance

Pressure monitoring

• Pressure sensors are installed in the cleanroom and adjacent areas to continuously monitor the pressure differential. Alarms can be set to alert operators if the pressure deviates from the set range.
• Regular calibration and maintenance of pressure sensors are essential to ensure accurate readings.

Leak detection and sealing

Periodic inspections are conducted to detect any leaks in the cleanroom envelope, such as around doors, windows, and duct penetrations. Leaks are sealed to maintain proper pressurization.

Smoke tests or other leak detection methods can be used to identify potential leakage points.