ISO Class vs. Old Class 100, 10,000 and 100,000: What Cleanroom Buyers Need to Know

If a cleanroom purchasing specification still says Class 100, Class 10,000, or Class 100,000, do not assume that the terminology itself is the full requirement. These are legacy cleanroom classification terms associated with Federal Standard 209E. The standard was canceled by the U.S. General Services Administration in November 2001, and ISO 14644-1 and ISO 14644-2 subsequently became the international framework used for cleanroom air classification. In common industry practice, Class 100 is associated with ISO Class 5, Class 10,000 with ISO Class 7, and Class 100,000 with ISO Class 8.

For buyers, however, knowing this correspondence is only the starting point. The real challenge is understanding what the classification refers to, what the supplier is actually promising, and what evidence should be requested before a product is approved.

Why Are Buyers Still Seeing "Class 100" on Cleanroom RFQs?

Old cleanroom terminology has not disappeared simply because the original standard was withdrawn. Long-running supplier lists, internal specifications, customer drawings, SOPs, and purchasing templates may continue to use terminology that was created decades ago.

That does not automatically make the requirement invalid.

A customer who writes "Class 100 cleanroom" may still have a perfectly clear contamination-control objective. The problem is that the wording can leave too much room for interpretation when it is transferred from one company to another.

For example, a buyer may send an RFQ for a wipe suitable for a Class 100 environment. One supplier may interpret this as a request for a product manufactured in an ISO 5 area. Another may understand it as a low-lint wipe intended for use in ISO 5. A third may simply use "Class 100 compatible" as a marketing description.

All three responses can look similar on paper while representing different things.

That is why old terminology should be translated rather than blindly copied.

How Do Class 100, 10,000 and 100,000 Correspond to ISO Classes?

The commonly used cross-reference is:

FDA documents continue to show these pairings in practical regulatory contexts, including Class 100 (ISO 5), Class 10,000 (ISO 7), and Class 100,000 (ISO 8).

But this should be treated as a cross-reference between classification systems, not as a simple renaming exercise.

ISO 14644-1 classifies cleanroom and clean-zone air according to the concentration of airborne particles at specified particle-size thresholds. The standard considers particle populations with lower threshold sizes from 0.1 µm to 5 µm and uses airborne particle counters to determine particle concentration at designated sampling locations.

So, when a purchasing document changes "Class 100" to "ISO 5," the terminology has been modernized, but the underlying specification still needs to be understood.

The Most Important Question: What Does "ISO 5" Actually Describe?

This is where many purchasing mistakes begin.

ISO 14644-1 is fundamentally a classification of air cleanliness by airborne particle concentration. It does not automatically classify the cleanliness of every item placed inside that room. It also does not define the physical, chemical, radiological, viable, or other nature of airborne particles.

That distinction matters for cleanroom consumables.

Consider a supplier statement such as:

"Suitable for ISO 5 cleanrooms."

That statement does not, by itself, tell you whether the supplier is describing:

the room where the product was manufactured,

the environment where it was packaged,

the intended application of the product,

the particle performance of the product,

or a combination of these factors.

These are different questions.

A product can be manufactured in a controlled environment, yet the buyer may still need product-specific information about particle release, lint, residues, packaging, or other contamination characteristics.

Why "Class 100 = ISO 5" Is Not Enough for Procurement

Suppose a buyer receives three quotations for cleanroom wipes. All three suppliers state "ISO 5" or "Class 100."

It may look like the products are equivalent.

They are not necessarily equivalent.

The buyer should ask what exactly has been tested and what the claim is based on. A useful procurement review may include:

1. The product itself
What material is used? What is the structure? Is it woven, knitted, microfiber, or nonwoven? How does it behave during wiping?

2. Particle and lint performance
Has the product been tested for particle release or other cleanliness characteristics relevant to the application?

3. Manufacturing environment
Where is the product converted, cleaned, packed, and sealed?

4. Packaging
Is it single-bagged, double-bagged, vacuum-packed, or packaged in another controlled format?

5. Documentation
Does the supplier provide test data, batch documentation, or other evidence that relates to the actual product being supplied?

The important point is simple:

"ISO 5" should not become a substitute for the complete product specification.

A Cleanroom Class Describes the Environment, Not Automatically the Product

This distinction becomes especially important when purchasing wiping products.

For example, a buyer sourcing materials for display manufacturing may need products such as LCD Panel Cleaning Wipes, but the fact that the wipes will be used in an ISO 5 area does not, by itself, define every performance requirement of those wipes.

The application may require low particle generation, controlled lint, suitable absorbency, low residue, or compatibility with a particular cleaning process. Those characteristics need to be addressed separately from the room classification.

In other words:

Cleanroom classification answers an environmental question. Product specification answers a product question.

The two are related, but they are not interchangeable.

What Should Buyers Ask When a Supplier Says "ISO 5 Compatible"?

A more useful conversation starts with three questions.

Does "ISO 5" refer to the manufacturing environment or the product?

Ask where the ISO classification applies. A statement about the factory environment is not necessarily a statement about product performance.

What specific cleanliness characteristic has been tested?

Instead of asking only whether the product is "ISO 5 compatible," ask what was measured, by what method, and under what conditions.

Does the tested product match the supplied product?

This is often overlooked. A test report is most useful when the material, construction, size, processing, packaging, and configuration correspond to the product actually being purchased.

This approach helps buyers compare suppliers on evidence rather than terminology.

How Should an Old "Class 100" RFQ Be Rewritten?

An old specification may say:

Cleanroom wipes for Class 100.

A clearer modern specification could identify:

• Application: Use in an ISO Class 5 cleanroom
• Required properties: Low particle and low-lint performance
• Material: Defined according to the cleaning process
• Size: Specified wipe dimensions
• Packaging: Required bagging configuration
• Sterility: Sterile or non-sterile, where applicable
• Testing: Specific cleanliness or residue tests where required
• Documentation: Required test reports or batch records

This does not mean every RFQ needs every parameter. The point is to replace one vague label with the requirements that actually matter for the application.

For a highly controlled application, a buyer may also need sterile cleanroom wipes for ISO 5 with specific sterility, packaging, and documentation requirements. The phrase "ISO 5" alone would not define those requirements.

What If the Customer Still Uses "Class 100"?

There is no need to argue with the customer's terminology.

A practical approach is to keep the original wording and add the current ISO reference:

Class 100 (commonly corresponding to ISO Class 5)

Then confirm the actual acceptance criteria with the customer or engineering team.

This is especially useful when an old customer specification has been used for years. Keeping the historical term as a reference reduces the risk of accidentally changing the customer's intended requirement during an update.

Common Procurement Mistakes

One common mistake is treating the old and new systems as if they were simply two names for the same document. They are related, but the classification frameworks are different.

Another is assuming that a product made inside an ISO 5 facility is automatically equivalent to a product with demonstrated cleanliness performance.

A third is approving products because "ISO 5" appears in the product name.

A fourth is comparing suppliers only by cleanroom class instead of comparing their actual material information, testing, packaging, and documentation.

The safer approach is to use the classification as one part of the purchasing specification rather than the entire specification.

What Should a Cleanroom Buyer Put on the RFQ?

A well-structured RFQ should normally separate the requirement into several layers.

Environmental requirement:
Specify the ISO Class or legacy class used by the customer.

Product requirement:
Specify material, construction, size, absorbency, lint or particle requirements, and intended application.

Contamination requirement:
Add chemical residue, ionic contamination, microbial, or other requirements when relevant to the process.

Packaging requirement:
Define bagging, vacuum packaging, sterile packaging, or other handling requirements where necessary.

Documentation requirement:
State whether test reports, certificates of analysis, lot traceability, or other quality documents are required.

This structure makes quotations easier to compare because suppliers are responding to measurable requirements rather than interpreting one general phrase.

The Better Question Is Not "Class 100 or ISO 5?"

For cleanroom procurement, the more useful question is not simply whether Class 100 equals ISO 5.

The better question is:

What cleanliness level does the process require, and what measurable product characteristics must the supplier demonstrate?

The old terminology is still useful when communicating with customers who have legacy specifications. The ISO terminology is important for modern documentation. But neither one should replace the actual technical requirements of the application.

When buyers move from old terminology → ISO reference → application requirements → product evidence → supplier verification, they gain a much clearer basis for evaluating cleanroom consumables.

That is the real purpose of converting Class 100, Class 10,000, and Class 100,000 into modern ISO terminology: not simply to change the label, but to remove ambiguity from the purchasing process.