Cleanroom Classification / Clean Room Classification

When it comes to running a business, there are often high standards to be maintained, especially when it comes to cleanliness and keeping particles and microbial out. Cleanroom Industries, including the pharmaceutical, semiconductor, industrial, electronics, aerospace, and manufacturing all rely on having proper clean rooms. These rooms are environmentally controlled spaces, where airflow, temperature, humidity, and contamination are closely monitored. They limit the amount of air pollutants that enter the space, including vapors, dust, and microbial.

However, different industries have different qualifications and standards. There is a wide range of different classifications, allowing for different levels of control. DesignTek Consulting Group, LLC., can work with your company to establish your needs when it comes to clean room design, and construction.

For many industries, the importance of cleanrooms is crucial to the integrity of their products and maintaining high yields. As such, the construction of a cleanroom should consist of a rigorous protocol, ensuring that the proper precautions are taken. Our professionals will provide consulting and guidelines to determine which classification will best fit your process.

Cleanroom Standards/Clean Room Standards

Cleanrooms are classified by how many particles are in the air, as well as how big those particles are, within one cubic meter of air. The smaller the classification is, then the more sterile the clean room. These standards are used amongst different industries, some requiring a higher level of cleanliness.

ISO 14644-1 addresses the cleanroom classification in regards to cleanliness and particle sizes, ranging from 0.1 µm to 5.0 µm. Prior to introduction of ISO 14644-1 (Nov. 2001), Federal standard 209E (FED STD 209E) was main reference used to classify cleanroom cleanliness. Small numbers refer to ISO 14644-1, which indicates the number of particles 0.1 µm or larger allowed per cubic meter of air.

To comply with ISO standard, each classification requires a different air changes/hour, room velocity and filter coverage, ranging from ISO 3 (class1) having the highest air changes per hour (app.450 air changes/hour) at 100% filter coverage, to ISO 8 (class 100,000) having the lowest air changes per hour (app. 10-12 air changes/hour), at 5-10% filter coverage.

ISO Class 3, (Class1, FED STD 209E)

This is the highest level of air cleanliness out of all the cleanrooms, with the standard set at only 1,000 particles per cubic meter. These particles must be smaller than 0.1 µm, making it an intensely high standard of cleanliness. For slightly larger particles, such as those that are smaller than 0.2 µm, only 237 particles are allowed per cubic meter. These clean rooms have stringent construction requirements, as they require very low contamination (particles).

ISO Class 4, (Class 10, FED STD 209E)

This classification increases to 10,000 particles per cubic meter at 0.1 µm, allowing for slightly more flexibility. It also allows for more variations as particles get larger. For example, particles that are 0.2 µm, up to 2,370 particles can be found in each cubic meter. At 0.3 µm, you can find 1,020 particles, and for 0.5 µm, 352 particles per cubic meter can be allowed.

ISO Class 5, (Class 100, FED STD 209E)

Despite the fact that it’s ISO class 5, many people in the industry call this level Class 100. This is due to the FED STD 209 cleanroom classification of measurement, commonly known throughout cleanroom circles. With these particular clean rooms, particles that are smaller than 0.1 µm start at 100,000, and for less than 0.2 µm, measure at 23,700. These cleanrooms also allow for bigger particles than the previous two classes, allowing 832 particles that are less that 1 µm in size.

This particular class is also used for Grade A production. This grade is for a regular zone for high-risk production and involve a laminar air flow system. They are commonly used for filling zones, aseptic connections, stopper bowls, etc.


Additionally, these clean rooms are also commonly given the clarification of Grade B at Rest. This is the prime background environment in order to classify as a Grade A. Grade B at rest is primarily used when cleanrooms are built for aseptic preparation and filling. At rest, up to 350,000 particles under 0.5 µm can be found in the air. It’s crucial that it meets the Grade criteria to ensure that the product is packaged and sterilized.

ISO Class 6, (Class 1,000 FED STD 209E)

Commonly referred to as Class 1000 by the FED STD 209 standards, this class allows up to 1,000,000 particles that are smaller than 0.1 µm. It’s also similar to class 5., in that it allows for larger particles. In fact, up to 8,320 particles per cubic meter are allowed, as long as they are smaller than 1 µm.

ISO Class 7, (Class 10,000 FED STD 209E)

This particular class is often called class 10,000, and for particles smaller than 0.5 µm, there can be up to 352,000 cubic meters. For larger particles that still fall under 1.0 µm, there can be up to 8,320 particles. In addition, particles in this class can be up to 5 µm but are limited to 2,930 particles per square cubic meter.

In addition, ISO Class 7 is typically classified as Grade C. This means that at rest, 352,000 particles smaller than 0.5 µm can be present at any given time. During operation, this number multiplies to 3,500,000 particles. Most of these are generated due to the use of equipment and movement that occur.

ISO Class 8, (Class 100,000 FED STD 209E)

Also known as Class 100,000, ISO class 8 provides an environment that is slightly different than room air, allowing 3,520,000 particles that are smaller than 0.5 µm. For particles that are less than 5 µm, the room can have upwards of 29,300.

ISO Class 8 is also commonly associated with clean rooms that are Grade D. At rest, they are limited to less than 3,500,000 particles that are smaller than 0.5. During operation, this number isn’t specified, but allows for the largest grade differential.

If your manufacturing, pharmaceutical, semiconductor, or aerospace company is looking to build cleanrooms, the experts at DesignTek Consulting can provide you with the proper guidelines. With more than thirty-five years’ experience in cleanroom design and construction, and with proven records on our past cleanroom projects, we will ensure that your cleanroom specifications and standards are met and exceeds your expectation. For more information about cleanroom classification standards, design and construction, give us a call today, or visit us on the web.

ISO cleanroom classification standards