ISO classifications are based on international standards that regulate the acceptable cleanliness levels of each level of room. International Organization for Standardization SO 14644-1 provides the guidance for the acceptable air quality levels within the specific clean room ISO classes. Moreover, the cleanroom class is determined by the level of cleanliness the room complies with, according to the quantity and size of particles per volume of air.
At Clean Air Products, we can manufacture clean rooms that comply with various ISO classifications, fs209e and ISO cleanroom standards. Whether you are looking for a less strict class 7 or 8 clean room, or require a class 4 that maintain the strictest cleaning standards, Clean Air Products manufactures clean rooms to your exact specifications.
Contact us for more information regarding clean room ISO classes, standards and the advantages of each type of ISO class of clean room. Or call us at 888-985-7307 and we will be happy to discuss your clean room needs and answer any questions that you may have.
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Table 1 – Maximum number of particles in air by ISO class of cleanroom
Table 1 – Maximum number of particles in air by ISO class of cleanroom

What is an ISO Clean Room? 

A cleanroom is a specially engineered and carefully designed enclosed area within a manufacturing or research facility. These rooms allow for precise control, monitoring, and maintenance of an internal environment. The numerous ISO classifications are specifically designed to regulate: 
  • Temperature
  • Humidity
  • Airflow
  • Filtration
  • Pressure

 Each room requires a different level of cleanliness depending on the industry and application.

Cleanroom ISO Class Code Descriptions

Determining the correct cleanroom standards for a new product or business requires balancing many aspects. These can include process requirements, cost, performance and construction. Clean Air Products staff members work hands-on with you to review the basics of selection, and all applicable clean room industry requirements. Clean Air Products provides cleanrooms by ISO class, as well as additional cleanroom accessories to guarantee superior air quality and particle filtering. The following clean room classifications provide the recommended air changes per hour, per class of cleanroom:
  • ISO Class 1 - The “cleanest” cleanroom is ISO 1, used in industries such as life sciences and electronics that require nanotechnology or ultra-fine particulate processing. The recommended air changes per hour for an ISO class 1 clean room is 500-750, and the ceiling coverage should be 80–100%.
  • ISO Class 2 - 500-750 air changes per hour, with a ceiling coverage of 80-100%.
  • ISO Class 3 - 500-750 air changes per hour, with a ceiling coverage of 60-100%.
  • ISO Class 4 - 400-750 air changes per hour, with a ceiling coverage of 50-90%.
  • ISO Class 5 - 240-600 air changes per hour, with a ceiling coverage of 35-70%.
  • ISO Class 6 - 150-240 air changes per hour, with a ceiling coverage of 25-40%.
  • ISO Class 7 - 60-150 air changes per hour, with a ceiling coverage of 15-25%.
  • ISO Class 8 - 5-60 air changes per hour, with a ceiling coverage of 5-15%.

Cleanroom Industry Requirements & Classifications

Cleanroom requirements and standards are classified according to the number and size of particles permitted per volume of air in a specific amount of time. Clean Air Products engineers can provide guidelines and ISO class code descriptions for the class of cleanroom required for your specific application. Typically, businesses and organizations are aware of their cleanroom performance requirements because of customer, industry or government specifications. For example, government regulation USP 797 outlines specific requirements for pharmaceutical product manufacturing.
Cleanroom industry requirements are classified according to ISO 14644-1 cleanroom standards, which specifies basic requirements for cleanroom operations. Federal Standard 209E is still also used (see Table 1).
Large VHW Mod Cleanroom

ISO cleanroom classifications are rated according to how much of a particulate of a specific size exists per cubic meter, within a given enclosure (see second chart). Clean room classifications are based on an eight class rating system, with an ISO class 1 cleanroom being rated the most particle-free and ISO class 8 allowing the most particles. This cleanroom standard rating system provides the necessary information to make an informed decision based on your product needs. Most clean rooms fall into the class 6,7, or 8 categories.

Softwall cleanroom

ISO Cleanroom Standards & Requirements 

A cleanroom’s performance requirements identify the cleanroom class level required at a given state or condition. There are three levels of condition (states) for testing and characterizing the performance of cleanrooms: as-built, at rest and operational. Specific test methods for these three classifications are outlined in 14644-3:2005.

Clean Room Classifications for As-Built Systems

Most cleanrooms are rated and sold in the as-built category, which is categorized as an empty room with the filter system running, but without workers and production equipment. However, adding workers and equipment will introduce contamination and affect the room rating. A clean room may be rated ISO 6 at rest, but at ISO 7 during operation (see Table 1). To comply with performance requirements, the as-built empty room should be tested and benchmarked, followed by testing and documentation of the at-rest and operational states. If contamination in the at-rest or operational states is not in compliance, corrective steps need to be taken. These steps can range from examining the production process and number of workers in the cleanroom, to testing the room’s air flow performance.
In addition, cleanroom air flow performance can be cost-effectively upgraded by adding fan filter modules (FFM). For example, FFMs cover approximately 5-15% of an ISO class 8 cleanroom requirements for ceilings. Upgrading to an ISO 7 cleanroom requires 15-25% ceiling coverage and covering 25-40% of the ceiling changes the room to an ISO 6 Class (see Table 2).

Recommended Air Changes Per Hour for Cleanrooms

Table 2 – Recommended air changes and ceiling coverage by ISO class of cleanroom

Clean Room ISO Classifications & Industrial Applications 

Clean room design standards are utilized for a wide range of industries and applications. Each industry maintains specific clean room ISO requirements for their application needs. The clean room ISO classes that are utilized for certain industries are described below.


Due to numerous influences including temperature, humidity, EMI and static electricity, electronics production quality can suffer if the production room conditions are not pristine. Depending on the specificities of the electronic hardware that is being manufactured, cleanrooms in the range of ISO class 1-6 are generally recommended. 

Food Manufacturing 

Facilities that manufacture food and beverage products for human consumption are required to maintain certain levels of sanitation. ISO classes for cleanrooms in this industry differ widely due to the varying sensitivity of different food products to contamination. 


The biotechnology industry regularly handles numerous types of sensitive fluids, organic matter,