FS 209E

Undoubtedly the best know cleanroom classification levels are the Federal Standard 209E, it was issued in the United States in 1963 for the first time and subsequently revised several times until the final version F209E in 1992. In the absence of an international standard, for many years the FS209E was used internationally.There are thirteen classifications of air cleanliness from class M1 to M7 as shown in the FS209E table below.The standard also indicates the conditions in accordance to which the controls must be carried out:

  • as built: Clean rooms or clean zones ready to start operating but without production equipment and personnel.
  • as rest: Clean rooms or clean zones fitted with the relevant processing machines but without personnel
  • operational: Clean rooms or clean zones in ordinary working activities with personnel and running processing machines.

This standard also determines the characteristics of the air flow, distinguishing between unidirectional (instead of linear) and non unidirectional flow (instead of turbulent).It establishes the conditions for the measurement of particles and the instruments to use.

ISO 14644.1

The need for a new international standard that covered more cleanroom environmental parameters and practices led to the formation of a technical committee of the International Standards Organisation. In 1996 ISO (International Standards Organisation) issued a new standard ISO 14644.1 with the goal of standardisation of equipment, facilities and operational methods for cleanrooms and controlled environments.

Comparison of International Standards

Standard and Date Published

USA
209D
(1988)
USA
209E
(1992)
EEC
CGMP
(1998)
EN
ISO14644-1
(1999)
Germany
VD 12083
(1990)
ISO 1
ISO 2
1 M1.5 ISO 3 1
10 M2.5 ISO 4 2
100 M3.5 A & B ISO 5 3
1,000 M4.5 ISO 6 4
10,000 M5.5 C ISO 7 5
100,000 M6.5 D ISO 8 6

Federal Standard 209E

Fed.Std Max. Number of Particles/ m³ equal or above 
209E 0.1µm 0.2µm 0.3µm 0.5µm 1µm 5µm
M1 350 75.7 30.9 10
M1.5 1,240 265 106 35.3
M2 3,500 757 309 100
M2.5 12,400 2,650 1,609 353
M3 35,000 7,570 3,090 1,000
M3.5 26,500 10,900 3,530
M4 75,700 30,900 10,000
M4.5 35,300 247
M5 100,000 618
M5.5 353,000 2,470
M6 1,000,000 6,180
M6.5 3,530,000 24,700
M7 10,000,000 61,800

Cleanroom Classification according to EN ISO 14644-1

ISO Class Max. Number of Particles/ m³ equal or above  
0.1µm 0.2µm 0.3µm 0.5µm 1µm 5µm
ISO 1 10 2
ISO 2 100 24 10 4
ISO 3 1,000 237 102 35 8
ISO 4 10,000 2,370 1,020 352 83
ISO 5 100,000 23,700 10,200 3,520 832 29
ISO 6 1,000,000 237,000 102,000 35,200 8,320 295
ISO 7 352,000 83,200 2,930
ISO 8 3,520,000 832,000 29,300
ISO 9 35,200,000 8,320,000 293,000

GMP Guidelines – In addition to the ISO standard the Good Manufacturing Practice Guidelines are also applicable for pharmaceutical, food, cosmetic and medical applications.

EUG GMP Class Max. Number of Particles/ m³ equal or above  
GMP At Rest In Operation
Class 0.5µm 5µm 0.5µm 5µm
A 3,520 20 3,520 20
B 3,520 29 352,000 2,900
C 352,000 2,900 3,520,000 29,000
D 3,520,000 29,000
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