Clean Room Pressure Difference Influencing Factors And control Methods
A professional clean room must control the pressure difference to ensure that air flows from clean areas to non clean areas and from high cleanliness areas to low cleanliness areas during normal use, thereby maintaining clean air in the clean room at all times.
Essentially, pressure difference is: fresh air volume=exhaust air volume+pressure difference air volume. The fresh air volume refers to the volume of air entering the cleanroom per hour from outside the cleanroom. The exhaust volume refers to the volume of polluted air discharged from a clean room per hour. Only when the balance between fresh air volume, supply air volume, and pressure difference air volume is reached can a pressure difference be established.
In the process of establishing pressure difference, many influencing factors will be encountered. Below are some of the most common influencing factors and corresponding measures.
Changes in filter resistance in HVAC systems can cause variations in air supply volume and affect fluctuations in indoor pressure differentials. This can be manually controlled, and the control method is relatively simple. When using constant air volume valve to control the pressure difference, it can automatically maintain a constant air supply volume. Alternatively, a variable speed air supply fan can be used to control the fan speed based on the filter pressure difference or the difference between the actual air supply volume and the set air supply volume, in order to maintain a constant air volume.
The changes in wind direction and speed outside the cleanroom can cause changes in indoor pressure difference. This factor is also relatively easy to control. When building clean room, choose door, window, and sandwich wall panel structures with good air tightness. The pressure difference between each room in the cleanroom should be controlled above 5Pa, and the pressure difference between the cleanroom interior and the cleanroom exterior should be controlled above 10Pa. Establish a stable cleanroom interior pressure difference rule to cope with changes in wind direction and speed outside the cleanroom.
The entry and exit doors of personnel and goods cause changes in the pressure difference of the clean room. When the door of the cleanroom is opened, the pressure difference between different room in cleanroom, as well as between different cleanroom, all will be affected, and the internal and external air will flow. Studies have shown that the larger the temperature difference between the two sides of the cleanroom door, the greater the air exchange capacity. To prevent reverse flow, it is recommended to use an airflow velocity of 0.25m/s to 0.5m/s.
Suzhou Pharma Machinery Co.,Ltd.
2025/05/12
Icey
