Contact us  |  CALL + 44 (0)1565 722609

Portable and permanent cleanroom solutions from Moorfield

Cleanroom standards

Cleanroom standards

Many might be familiar with the old FS209E standard which contained six classes, this has been replaced internationally by the ISO 14644-1 classification system which adds two cleaner standards and one dirtier standard (see chart below). The "cleanest" cleanroom in FS209E is referred to as Class 1; the "dirtiest" cleanroom is a class 100,000.

ISO cleanroom classifications are rated according to how much particulate of specific sizes exist per cubic meter (see 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
0.1μm 0.2μm 0.3μm 0.5μm 1μm 5μm
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 changes over time — from the construction and installation of equipment to its operational status. ISO delineates three cleanroom classification standards: as-built, at-rest and operational. As instruments and equipment are introduced and particulates rise, an "as-built" cleanroom becomes an "at-rest" cleanroom. When people are added to the matrix, particulate levels rise still further in the "operational" cleanroom.

ISO 14644-2 describes the type and frequency of testing required to conform to certain standards. The following tables indicate mandatory and optional tests.

Required Testing (ISO 14644-2)

Schedule of Tests to Demonstrate Continuing Compliance

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)

Schedule of Additional Optional Tests

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