Cleanroom Classification: Understanding the Differences Between ISO Classes

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ISO Classes

Cleanrooms are essential environments for industries such as pharmaceuticals, electronics, and healthcare that require highly controlled, low-particulate environments for their manufacturing processes.

To ensure consistency and uniformity, cleanrooms are classified according to the International Organization for Standardization (ISO) standards. Understanding the different ISO classes can help businesses and organizations select the appropriate cleanroom for their needs and maintain proper standards for their industry.

In this article, we will examine the different ISO classes and their requirements, as well as other important factors to consider when operating a cleanroom.

ISO Classification Standards

ISO classification is based on the number of particles per cubic meter of air in the facility. This system of classification of cleanrooms ranges from ISO Class 1 (fewest particles) to ISO Class 9 (highest number of particles). Each class has specific requirements for particle size and quantity, and these requirements increase in stringency as the class number decreases.

ISO Class 1 Cleanrooms

The strictest cleanrooms, with the fewest particles, are ISO Class 1 cleanrooms. Less than 10 particles larger than 0.1 micrometres per cubic metre of air are allowed in class 1 cleanrooms. These cleanrooms are typically employed in industries that need a high standard of cleanliness, like semiconductor fabrication and nanotechnology.

To achieve this level of cleanliness, Class 1 cleanrooms need ultra-high efficiency particulate air (HEPA) filters and positive-pressure ventilation systems. Additionally, only qualified personnel are allowed to enter these cleanrooms with full body suits, gloves, masks, and hoods.

ISO Class 2 Cleanrooms

ISO Class 2 cleanrooms must have fewer than one hundred particles larger than 0.1 micrometers in size per cubic meter of air. These cleanrooms are used in applications that require high cleanliness, such as pharmaceutical manufacturing, medical device assembly, and microelectronics.

Class 2 cleanrooms also require HEPA filters and positive-pressure ventilation systems, but they may allow for the use of a reduced suit compared to Class 1 cleanrooms.

ISO Class 3 Cleanrooms

ISO Class 3 cleanrooms must have fewer than one thousand particles larger than 0.1 micrometers in size per cubic meter of air. These cleanrooms are used in industries such as optics, electronics, and aerospace. Class 3 cleanrooms also require HEPA filters and positive-pressure ventilation systems. However, they may allow for a reduced suit compared to Class 2 cleanrooms.

ISO Class 4 Cleanrooms

ISO Class 4 cleanrooms must have fewer than ten thousand particles larger than 0.1 micrometers in size per cubic meter of air. These cleanrooms are used in applications such as hard disk drive manufacturing, medical device assembly, and aerospace. Class 4 cleanrooms also require HEPA filters and positive-pressure ventilation systems, but they may allow for a lower air exchange rate than Class 3 cleanrooms.

ISO Class 5-9 Cleanrooms

ISO Class 5-9 cleanrooms are used in industries such as automotive manufacturing, food processing, and packaging.

These cleanrooms are less stringent than the previous four classes, with ISO Class 5 requiring fewer than one hundred thousand particles larger than 0.1 micrometers in size per cubic meter of air and ISO Class 9 requiring fewer than thirty-five thousand two hundred particles larger than 0.5 micrometers in size per cubic meter of air.

These cleanrooms typically use high-efficiency filters and positive-pressure ventilation systems.

Cleanroom Design Compliance

The design of a cleanroom is critical to maintaining compliance with ISO standards. Engineers must consider factors such as air pressure, temperature, humidity, and filtration systems to meet the requirements of each ISO class.

The design must also consider other aspects, such as the layout of the cleanroom, the flow of personnel, and equipment, to minimize the risk of contamination. Additionally, cleanroom design must consider the type of operations performed within the cleanroom and the types of materials and products that will be processed.

Companies are changing their cleanroom designs to keep pace with industry demands. Aerotech, a global expert in precision motion control and automation, recently announced that it plans to more than double its cleanroom space to accommodate future growth, according to a February 2023 article published on cleanroomtechnology.com.

Maintenance and Cleaning of Cleanrooms

Regular maintenance and cleaning of cleanrooms is essential to ensure compliance with ISO standards. Maintenance tasks such as filter replacement, HVAC system cleaning, and regular inspections are critical to ensure that the cleanroom continues to meet the required ISO classification.

According to a 2023 article published in Facility Executive Magazine, precise control of relative humidity levels is critical for accurate test results inside cleanroom environments. Even minor fluctuations in humidity caused by HVAC system start-up or seasonal changes, can impact the efficacy of sensitive testing. In unregulated environments, the longevity of expensive equipment, including spectrometers and electron microscopes, may also be significantly reduced.

The cleaning process must be performed with specific procedures and cleaning agents to prevent contamination, and the frequency of cleaning must be determined by the cleanroom’s usage and classification. Furthermore, the personnel responsible for cleaning the cleanroom must be trained in the proper cleaning procedures and must use appropriate protective equipment to prevent contamination.

Testing and Certification of Cleanrooms

Testing and certification of cleanrooms are essential to ensure that the facility meets the requirements of the appropriate ISO class. Testing can include particle counting, airflow testing, and air exchange rate measurements.

Cleanrooms must be certified regularly by qualified third-party certification bodies to ensure ongoing compliance with ISO standards. Certification ensures that the cleanroom remains in compliance with ISO standards and can provide confidence to the users that the cleanroom meets the required cleanliness standards.

In November 2022, Cintas Corporation conducted a grand-opening ceremony to inaugurate its latest cleanroom facility in the Syracuse region of New York. As per the report published on Business Wire, the state-of-the-art facility located in Marcy, N.Y., bolsters Cintas’ cleanroom infrastructure across the United States, enhancing the company’s ability to meet the increasing demand for its services.

Conclusion

Cleanrooms are essential in many industries, and their design and maintenance are critical to ensure their effectiveness. The ISO classification system provides a framework to define cleanroom cleanliness levels and requirements. Each ISO class has specific requirements for particle size and quantity, and these requirements increase in stringency as the class number decreases.

Cleanroom design, maintenance, and testing must be performed following strict procedures to ensure compliance with ISO standards. These measures will help prevent contamination, improve product quality, and enhance worker safety in cleanroom environments.