What is class 100000 cleanroom?
An Expert Guide to Class 100,000 CleanroomsBy Jason Peng, Cleanroom Design Exper

Author:Jason Peng
Cleanroom Engineering Technology Manager of Deiiang Company.
Product R&D Manager of GDC Inc. Cleanroom Equipment Manufacturing Company.
Executive Director of Guangdong Cleanroom Industry Association of China.
Engaged in R&D of related products for 15 years, with rich relevant technical experience
In the world of precision manufacturing and scientific research, controlling environmental contamination is not just a preference—it's an absolute necessity. A class 100,000 cleanroom represents a critical level of controlled environment, bridging the gap between general manufacturing spaces and ultra-stringent cleanroom classes. This article provides a comprehensive, authoritative breakdown of its standards, operational principles, and industrial applications, serving as an essential resource for engineers and facility managers.
A Class 100,000 cleanroom is defined by its maximum allowable concentration of airborne particles. The classification number itself reveals the key metric: it signifies that no more than 100,000 particles (≥0.5 microns in size) are permitted per cubic foot of air. This is the foundational benchmark against which the room's performance is continuously measured and validated.
While this particle count is significantly higher than that of more stringent classes (like Class 100 or ISO 5), it provides a substantial barrier against environmental contaminants compared to a typical office space, which may contain millions of particles per cubic foot. This controlled environment is sufficient to ensure product quality and process integrity in numerous industries where absolute sterility or ultra-fine particulate control is not the primary concern.
The now-defunct U.S. Federal Standard 209E, "Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones," was the pioneering document for cleanroom classification. First established in 1963 and iteratively updated (with the 'E' version being the last in 1992), it provided the global framework for defining cleanroom cleanliness by measuring particles per cubic foot. Its user-friendly class names (Class 100, Class 10,000, Class 100,000) became industry shorthand worldwide.
The standard defined six major classes: M1, M1.5, M2, M3, M4, M5, M6, and M7, but the common nomenclature used the rounded metric equivalents. The table below outlines the particle count limits for the relevant classes.
| FED-STD-209E Class | Equivalent ISO Class | Max Particles per ft³ (≥0.5 µm) | Max Particles per m³ (≥0.5 µm) |
|---|---|---|---|
| Class 100,000 | iso 8 | 100,000 | 3,520,000 |
| Class 10,000 | ISO 7 | 10,000 | 352,000 |
| Class 100 | ISO 5 | 100 | 3,520 |
FED-STD-209E was officially canceled in 2001 by the U.S. General Services Administration and superseded by the international standard ISO 14644-1. The relationship between the two is direct:
Class 100,000 and ISO 8 are two names for the exact same level of cleanroom cleanliness. The term "Class 100,000" originates from the retired U.S. FED-STD-209E, which measured particles per cubic foot. "ISO 8" is the official designation from the current international standard, ISO 14644-1, which uses particles per cubic meter as its benchmark. For clarity and professionalism, using the term ISO 8 is recommended in all new projects and technical documentation.
While the classification is identical, achieving and maintaining it requires adherence to the testing and monitoring protocols outlined in ISO 14644-2 and other parts of the standard. This ensures that the cleanroom not only meets the particle count at a single point in time but operates consistently within its specified parameters through rigorous periodic testing.

The cornerstone of any cleanroom is its filtration system. For an ISO 8 (Class 100,000) environment, this typically involves a three-stage process:

Cleanroom filtration system with HEPA filters
The filtration system does not operate in isolation; it is fully integrated into a specialized Heating, Ventilation, and Air Conditioning (HVAC) system. This system is responsible for controlling not only cleanliness but also temperature, humidity, and pressurization. A positive pressure is maintained inside the iso 8 cleanroom relative to adjacent, less-clean areas to prevent unfiltered air from infiltrating.
For many ISO 8 applications, a highly efficient and flexible solution is the use of Fan Filter Units (FFUs). An FFU is a self-contained module that incorporates a HEPA filter and a blower fan. A ceiling grid of FFUs, like those designed and supplied by Deiiang™, creates a clean, downward laminar airflow pattern. This method is often more energy-efficient and easier to install or modify than a traditional centralized HVAC system with extensive ductwork, making it ideal for large-area Class 100,000 environments.
Maintaining an ISO 8 cleanroom requires strict adherence to protocols beyond just the air handling system. Key requirements include:
Class 100,000 (ISO 8) cleanrooms are employed in a wide range of industries where contamination control is important but ultra-sterile conditions are not critical.

The Class 100,000, or ISO 8, cleanroom remains a vital and cost-effective solution for many manufacturing and processing industries. Its design, centered on robust three-stage HEPA filtration—often implemented efficiently via FFU systems—and strict operational protocols, provides a controlled environment that effectively mitigates particulate contamination. Understanding its standards, principles, and requirements, as outlined by experts like Deiiang™'s Jason Peng, is essential for any organization looking to implement or manage a facility that meets this globally recognized classification, ensuring product quality, safety, and regulatory compliance.
A: No, it was officially canceled in 2001. However, its class names (like Class 100,000) are still widely used as informal industry shorthand for the equivalent ISO classes.
A: According to ISO 14644-2, particle count tests should be conducted every 6 months. Other tests, like pressure differential and airflow velocity, should be performed at an even higher frequency (e.g., every 3 months).
A: Yes, in fact, most systems recirculate a large portion of the internal air (often over 80%) through the HEPA filters to maintain cleanliness, while a smaller percentage of fresh air is introduced for climate control and pressurization.
A: While it varies based on design and activity, a typical ISO 8 cleanroom requires between 15 to 30 air changes per hour (ACH) to maintain its classification.
A: Seamless, non-shedding materials like epoxy resin, vinyl sheet flooring, or raised access floors with sealed joints are standard to allow for easy cleaning and prevent particle generation.
A: Yes, a single airlock is typically the minimum requirement to serve as a transition zone for personnel and materials, helping to maintain the positive pressure and prevent contamination ingress.