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05 Nov ISO 5 vs ISO 6 Cleanrooms: Understanding the Differences

Posted at 10:12h in Blog by

Choosing between ISO 5 vs ISO 6 cleanrooms can be difficult, especially if you’re unfamiliar with the technical language used in cleanroom contexts. Of course, understanding the differences between the two can help you decide which one best fits your project. In this article, we’ll discuss ISO 5 vs ISO 6 cleanrooms, covering their particle counts, features, costs, and more.

Comparing ISO 5 vs ISO 6 Cleanrooms

The main difference between ISO 5 vs ISO 6 cleanrooms is, as you might have guessed, in the number and sizes of airborne particles allowed. ISO 5 cleanrooms are much more strict than ISO 6 ones.

Though the difference seems small between ISO 5 and ISO 6 (a mere one number difference), ISO 5 cleanrooms typically require more advanced features than lower-tier spaces.

For example, ISO 5 spaces most often need to use unidirectional airflow, because the level cleanliness and air change rates required. And because of these advanced features, ISO 5 cleanrooms, all else being equal, are significantly more expensive than ISO 6 ones.

Let’s take a look at some of the details to see what makes each cleanroom classification different.

ISO 5 Cleanrooms ISO 6 Cleanrooms
Particle Counts Allows up to 3,520 particles (0.5 micrometers or larger) per cubic meter. Allows up to 35,200 particles (0.5 micrometers or larger) per cubic meter, 10 times more than ISO 5.
Air Change Requirements Requires 240 to 600 air changes per hour. Requires 150 to 240 air changes per hour, generally fewer than ISO 5.
Airflow Often requires unidirectional airflow. Typically does not require unidirectional airflow; turbulent airflow is sufficient.
Relative Costs More expensive due to high ACH, advanced filtration, and unidirectional airflow. Less expensive to build and operate due to lower ACH requirements and more relaxed filtration standards.
Typical Applications Semiconductor manufacturing (photolithography), pharmaceutical filling rooms, aerospace, medical devices. Food processing and packaging, pharmaceutical compounding, optical manufacturing.

Particle Counts in ISO 5 vs ISO 6 Cleanrooms

  • ISO 5 Cleanrooms: These spaces allow a maximum of 3,520 particles of 0.5 micrometers or larger per cubic meter.
  • ISO 6 Cleanrooms: These spaces, on the other hand, permit up to 35,200 particles per cubic meter, 10 times more than ISO 5.

As you may notice from the chart below, both ISO 5 and ISO 6 environments must control particles of the same sizes, but ISO 6 allows a much higher number of particles across all sizes, one order of magnitude more than ISO 5.

Chart showing maximum allowable particle concentrations for ISO cleanroom classes 1 through 9 at various particle sizes.

Air Change Requirements

Air change rates are important in keeping a space as clean as its classification requires. In cleanroom contexts, air changes per hour (ACH) is a metric that indicates how many times the air is fully replaced each hour. The higher the number of ACH, the cleaner the space will be. As you will see below, ISO 5 and ISO 6 cleanrooms vary a lot in terms of air change requirements.

  • ISO 5 Cleanrooms: They typically need between 240 and 600 ACH.
  • ISO 6 Cleanrooms: These spaces usually require 150 to 240 ACH.

Keep in mind that the number of ACH is just an estimate, and the real number required depends on the design of the building and other factors. Still, it’s clear that different cleanroom classifications may have significantly different airflow requirements.

Ceiling of a cleanroom with HEPA filters and lighting panel, alongside an illuminated exit sign.

Relative Costs of ISO 5 vs ISO 6 Cleanrooms

All else being equal, the price of a cleanroom goes up the higher the ISO class. This is because extra features, higher air change rates, and other factors all lead to higher costs, both to construct the cleanroom but also to maintain it. Let’s take a look specifically at the differences between ISO 5 vs ISO 6 costs.

  • ISO 5 Cleanroom Costs: Because of the higher number of air change rates, advanced filtration, and unidirectional airflow requirements, these spaces will cost significantly more to construct and maintain.
  • ISO 6 Cleanroom Costs: ISO 6 cleanrooms, on the other hand, are less expensive to build and operate because of the lower number of air changes required, as well as more relaxed filtration needs. Also, in most cases, ISO 6 cleanrooms do not need to use unidirectional airflow.

Applications of ISO 5 Cleanrooms

ISO 5 cleanrooms are necessary in many industries, especially where the smallest particles can wreak havoc. In some of these fields, even a single particle can damage products:

  • Semiconductor manufacturing (photolithography): Keeps wafer patterns free from contamination.
  • Pharmaceuticals (filling rooms): Makes sure that medications remain uncontaminated during final packaging.
  • Aerospace: Prevents particles from seeping into products during production; contamination in aerospace parts can lead to catastrophic failures.
  • Medical devices: Keeps medical equipment and devices safe for use.

Applications of ISO 6 Cleanrooms

A clean, organized laboratory with workstations, lab equipment, and storage shelves, used for scientific research or testing.

ISO 6 cleanrooms are used in industries where contamination control is important, but slightly higher levels of particles are acceptable. Some common applications of them include:

  • Food processing and packaging: Keeps food production lines clean.
  • Pharmaceutical compounding: Protects the formulation of various medications.
  • Optical manufacturing: Keeps lenses and other optical parts free from dust and imperfections.

The Bottom Line

ISO 5 and ISO 6 cleanrooms, though seemingly close together (only a one number difference), often have very different features. ISO 5 cleanrooms are much stricter in terms of particle limits, while ISO 6 spaces are about one-tenth as strict. Ultimately, choosing the right cleanroom classification depends on the size of the particles that cause issues to whatever processes happen within the space. It’s a balancing act between costs, regulations, and industry requirements.

Still unsure of the differences? Speak with the experts at Allied Modular to clear up any confusion and get a free quote on a new cleanroom.

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