Cleanroom Quality and Standards

Table of Contents

Introduction
Airborne Particulate Cleanliness Class Comparison
Airborne Particulate Cleanliness Classes (by Cubic Meter)
Required Testing (ISO 14644-2)
Optional Testing (ISO 14644-2)

Introduction

Many might be aware of the old FS209E standard which consisted of six classes, but this has been replaced internationally by the ISO 14644-1 classification system which incorporates two cleaner standards and one dirtier standard (refer chart below). The "cleanest" cleanroom in FS209E is stated as Class 1; the "dirtiest" cleanroom is a class 100,000.

ISO cleanroom classifications are rated based on how much particulate of specific sizes exist per cubic meter (refer to second chart). The "cleanest" cleanroom is a class 1 and the "dirtiest" a class 9. ISO class 3 is approximately equal to FS209E class 1, while ISO class 8 approximately equals FS209E class 100,000.

Airborne Particulate Cleanliness Class Comparison

ISO 14644-1 Federal Standard 209E
ISO Class English Metric
ISO 1
ISO 2
ISO 3 1 M1.5
ISO 4 10 M2.5
ISO 5 100 M3.5
ISO 6 1,000 M4.5
ISO 7 10,000 M5.5
ISO 8 100,000 M6.5
ISO 9

Airborne Particulate Cleanliness Classes (by Cubic Meter)

Class Number of Particles per Cubic Meter by Micrometer Size
0.1 μm 0.2 μm 0.3 μm 0.5 μm 1 μm 5 μm
ISO1 10 2
ISO2 100 24 10
ISO3 1,000 237 102 35
ISO4 10,000 2,370 1,020 352 83
ISO5 100,000 23,700 10,200 3,520 832
ISO6 1,000,000 237,000 102,000 35,200 8,320 293
ISO7 352,000 83,200 2,930
ISO8 3,520,000 832,000 29,300
ISO9 35,200,000 8,320,000 293,000

In cleanrooms, particulate concentration alters over time — from the creation and installation of equipment to its operational status. ISO delineates three cleanroom classification standards at-rest, as-built, and operational. As instruments and equipment are added and particulates rise, an "as-built" cleanroom transforms into an "at-rest" cleanroom.

When people are added to the matrix, particulate levels rise much more in the "operational" cleanroom. ISO 14644-2 describes the frequency and type of testing needed to conform to definite standards. The following tables specify mandatory and optional tests.

Required Testing (ISO 14644-2)

Test Parameter Class Maximum Time Interval Test Procedure
Particle Count Test ≤ ISO 5 6 Months ISO 14644-1 Annex A
> ISO 5 12 Months
Air Pressure Difference All Classes 12 Months ISO 14644-1 Annex B5
Airflow All Classes 12 Months ISO 14644-1 Annex B4

Optional Testing (ISO 14644-2)

Test Parameter Class Maximum Time Interval Test Procedure
Installed Filter Leakage All Classes 24 Months ISO 14644-1 Annex B6
Containment Leakage All Classes 24 Months ISO 14644-1 Annex B4
Recovery All Classes 24 Months ISO 14644-1 Annex B13
Airflow Visualization All Classes 24 Months ISO 14644-1 Annex B7

This information has been sourced, reviewed and adapted from materials provided by Clean Environments.

For more information on this source, please visit Clean Environments.

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