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CLEANROOM MANUFACTURING · STANDARDS

What Are Cleanroom Classes?

Cleanroom classes define how many airborne particles a cleanroom may contain. ISO 14644-1 sets nine classes, from ISO 1, the cleanest, to ISO 9, based on the number of particles of a given size per cubic metre of air. ISO 5 to ISO 8 cover most manufacturing, and EU GMP adds Grades A to D for sterile medicines.

01

The Short Answer

A cleanroom is classified by counting the airborne particles in it. ISO 14644-1 is the international standard: each class sets the maximum number of particles at or above a given size in one cubic metre of air, and each step up the scale allows ten times more particles than the one below.

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    ISO 5 Up to 3,520 particles of 0.5 µm or larger per m³. Aseptic filling, semiconductor lithography.
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    ISO 6 Up to 35,200. Semiconductor and optics production.
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    ISO 7 Up to 352,000. Electronics assembly, medical devices, pharmaceutical preparation.
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    ISO 8 Up to 3,520,000. Packaging, gowning rooms and general controlled areas.
02

GMP Grades and Former US Classes

Sterile medicine manufacturing in Europe uses the EU GMP grades: Grade A matches ISO 5, Grade B is ISO 5 at rest and ISO 7 in operation, Grade C is ISO 7 at rest and ISO 8 in operation, and Grade D is ISO 8 at rest. The old US Federal Standard 209E classes, withdrawn in 2001, are still quoted: Class 100 is roughly ISO 5, Class 10,000 is ISO 7 and Class 100,000 is ISO 8.

03

What Cleanroom Classes Mean for Equipment

The tighter the class, the more closely every object in the room is scrutinised as a particle source. Our guide to clean room computers explains how fanless design, sealed surfaces and mounting change from ISO 8 to ISO 5.