Cleanroom Classification Standards

2024-09-06

Clean rooms maintain specific cleanliness and environmental conditions by controlling particles, pollutants, etc. in the air. They are classified based on the number of particles in the air, mainly referring to US federal standards and ISO standards; Federal Standard 209 classifies particles of 0.5mm or more per cubic foot in the United States; ISO standards are more detailed, covering different levels from 1 to 300000. The smaller the number, the higher the cleanliness and the corresponding increase in cost.

● Ventilation rate and purification time requirements

Different levels of cleanrooms correspond to specific hourly air exchange rates and air purification times, for example, 100000 level cleanrooms require 18-25 air exchanges per hour, with complete purification not exceeding 40 minutes; At a level of 10000, air exchange is required 25-30 times per hour, and the complete purification time is shortened to within 30 minutes.

Require to achieve it within a certain period of time (such as 15 to 20 minutes). For higher standard of class 100 clean room or Class 1000, the air exchange rate can reach hundreds of times per hour, ensuring rapid and effective removal of particles and maintaining extremely high air cleanliness. The purification time is shortened to a few minutes or even less, measured in seconds, reflecting the strict demand for immediate pollution control.

● Air filtration and circulation system

The core of a clean room lies in its efficient air filtration and circulation system. Usually, a multi-stage filtration mechanism is used, including a primary filter to intercept large particles, a medium efficiency filter to further remove smaller particles, and high-efficiency filters (HEPA) and ultra high efficiency filters (ULPA) to capture particles below 0.3 microns, achieving extremely high filtration efficiency. Air circulation follows specific paths, such as laminar flow with top supply and bottom return air, or non unidirectional flow design using turbulence principles to ensure uniform distribution and rapid renewal of indoor air.

● Temperature, humidity, and pressure control

In addition to particle control, clean rooms also need to strictly monitor temperature, humidity, and indoor pressure. The temperature is usually maintained between 18 ° C and 26 ° C, and the humidity is controlled within the range of 45% to 65% to prevent static electricity accumulation and microbial growth. Positive pressure environment design prevents external unpurified air from flowing in, while for areas with higher cleanliness requirements, higher positive pressure differentials are implemented to ensure environmental isolation and protection.

● Personnel and material entry and exit management

Personnel entering and leaving the clean room must follow strict changing procedures, wear dust-free clothing, masks, gloves, and other dust-proof equipment, and remove attached particles through facilities such as air showers. Materials entering also need to undergo purification treatment, and high-risk items may also require sterilization. In addition, the separation of pedestrian and logistics channels reduces the risk of cross contamination and ensures the sustained stability of the internal environment.

● Monitoring and maintenance

The performance of the clean room needs to be regularly tested and verified, including key parameters such as particle concentration, microbial content, temperature and humidity, and pressure difference. Use professional equipment such as light scattering particle counters and temperature and humidity meters for monitoring to ensure that all indicators continuously meet the prescribed standards. At the same time, regular cleaning and replacement of filters, floors, walls, etc. are necessary measures to maintain long-term cleanliness.

In summary, the cleanroom classifications standards are not only related to the precise control of air quality, but also involve a wide range of environmental management strategies. From air treatment to personnel behavior, every link needs to be carefully designed and strictly implemented to ensure that production and scientific research activities can proceed smoothly in a highly controlled environment.