SMB Validation

What are the clean room class limits according Federal Standard 209?

Note! Federal Standard 209E is canceled and superseded by International Organization for Standardization (ISO) Standards - International Standards for Cleanrooms and associated controlled environments, ISO 14644.

Clean room maintained virtually free of contaminants, such as dust or bacteria, are used in laboratory work and in the production of precision parts for electronic or aerospace equipment.

The air quality of a clean rooms are described in Federal Standard 209 "Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones" (A through D) where the classes are named after the maximum number of particles of 0.5 micrometers or more in diameter which is acceptable in air.



Maximum Number of Particles in Air
(particles per cubic foot air)
Class
0.1 µm
0.2 µm
0.3 µm
0.5 µm
5.0 µm
1
35
7.5
3
1
10
350
75
30
10
100
750
300
100
1,000
1,000
7
10,000
10,000
70
100,000
100,000
700


In a clean room rated as "Class 10,000" there may not exists more than 10,000 particles larger than 0.5 microns in a cubic foot of air.

Classes and their Typical Uses

Federal Standard 209 E uses metric units and the classes are defined as:



Maximum Number of Particles in Air
(particles per volume unit)
Class
0.1 µm
0.2 µm
0.3 µm
0.5 µm
5 µm
SI
English
ft³
ft³
ft³
ft³
ft³
M 1
350
9.91
75.7
2.14
30.9
0.875
10.0
0.283
M 1.5
1
1,240
35.0
265
7.50
106
3.00
35.3
1.00
M 2
3,500
99.1
757
21.4
309
8.75
100
2.83
M 2.5
10
12,400
350
2,650
75.0
1,060
30.0
353
10.0
M 3
35,000
991
7,570
214
3,090
87.5
1,000
28.3
M 3.5
100
26,500
750
10,600
300
3,530
100
M 4
75,700
2,140
30,900
875
10,000
283
M 4.5
1,000
35,300
1,000
247
7.00
M 5
100,000
2,830
618
17.5
M 5.5
10,000
353,000
10,000
2,470
70.0
M 6
1,000,000
28,300
6,180
175
M 6.5
100,000
3,350,000
100,000
24,700
700
M 7
10,000,000
283,000
61,800
1,750