Cleanroom ISO Classification

Understanding Cleanroom ISO Classifications

ISO classifications are a vital component of modular cleanroom design and construction. These classifications, also known as cleanroom classifications, measure the number of particles present within one cubic meter of a given space. The standards for cleanrooms are internationally recognized by the Cleanrooms and Associates Controlled Environments and are ranked based on their function. Our specialty lies in ISO class 5 through 8 cleanrooms. These classifications are essential for the design, installation, and construction of modular cleanrooms and are used across industries that require extreme cleanliness to optimize production. 

In order to ensure optimal results, the cleanliness level of a cleanroom facility must correspond with its intended application. For instance, semiconductor cleanrooms are enclosed environments within a manufacturing facility that must meet specific ISO requirements to maintain absolute control over air quality, particle count, airflow, humidity, and temperature. This is because even a single airborne particle can cause damage to an entire chip or device. Without the proper ISO classification, semiconductor manufacturers run the risk of contamination or producing defective units.

Modulus Cleanrooms Modular Hardwall Biotech Cleanroom ISO 5 and 7 Freemont 1
Modulus Cleanrooms Modular Hardwall Electronic Cleanroom ISO 6 Livermore

How ISO Classifications Relate to Hardwall and Softwall Cleanrooms

Cleanrooms can be designed using either hardwall or softwall construction methods, depending on the specific requirements and applications. When designing a modular cleanroom for a specific application, we guide you through what needs to be considered for a specific application, such as the ISO classification, airflow and air change per hour requirements, filtration, particle control, and gowning. Compared to conventional cleanroom construction, a modular cleanroom is easier to modify or disassemble and move to an alternate site and can be upgraded to a higher classifications.

Hardwall Cleanroom

Structure: Hardwall cleanrooms have rigid walls and ceilings constructed from durable materials such as stainless steel, aluminum, and panels.

Containment: Hardwall cleanrooms offer a high level of containment and airtightness due to the nature of the walls and ceilings. They provide physical barriers against external contamination sources. 

Customization: Hardwall cleanrooms allow for more customization options in terms of size, layout, and integration of equipment. They can accommodate all ISO requirements. 

Softwall Cleanrooms

Structure: Softwall cleanrooms feature flexible walls made from materials like vinyl or PVC curtains, which are suspended from an overhead support structure. 


Containment: Softwall cleanrooms offer a lower level of containment compared to hardwall cleanrooms. The flexible walls are less resistant to air leakage. Softwall cleanrooms can be easily adjusted, reconfigured, or replaced as needed.


Customization: Hardwall cleanrooms allow for more customization options in terms of size, layout, and integration of equipment. They can accommodate ISO class range ISO 7-8 requirements. 

Cleanroom Classifications Explained

Cleanrooms are classified by the number and size of particles found in a cubic meter of air. They are classified under 

ISO 14644-5:2004 and Federal Standard 209E. For example, a cubic meter of urban air has around 35,200,000 particles that are 0.5 microns or larger. By comparison, an ISO 5 cleanroom allows only 3,520 particles of that size in the same volume of air. 


Design Guide for Cleanrooms

ISO 14644-1 FED STD 209E

*This table relates to cleanliness class to both the average air velocity in the cleanroom and rate of air changes per hour. The range of values listed is a consensus of existing practice and is not intended to indicate design. It is up to the designer and end user to arrive at a value either inside or outside the range that is consistent with project needs. Generally the approach is to the higher values in cleanrooms housing a relatively dirty process or where the cleanroom garment program or discipline is relaxed. The lower end of the range is more appropriate for cleaner processes and a more disciplined cleanroom gowning procedure.


* Ideal differential pressurization range: (“w.g.”) 0.02-0.08


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