Clean Rooms - Federal Standard 209

Clean rooms virtually free of contaminants like dust or bacteria.

Clean room maintained virtually free of contaminants like dust or bacteria are required for types of laboratory work and in the production of electronic and aerospace equipment precision parts.

Particle Sizes

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

Clean Rooms - Maximum Number of Particles in Air - Federal Standard 209
Class	Maximum Number of Particles in Air (particles per cubic foot air)
	Particle Size
	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
1000				1000	7
10000				10000	70
100000				100000	700

clean room classes and number size particles diagram

In a clean room rated as "Class 10000" there may not exists more than 10000 particles larger than 0.5 microns in a cubic foot of air.

Classes and their Typical Uses

Class 1 & 10 - production laboratories for electronic integrated circuits ..
Class 100 - production areas for photo labs, medical implants ..
Class 10000 - production locales for TV tubes, hospital operating theaters ...
Class 100000 - production of ball bearings

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

For full table - rotate the screen!

Clean Rooms - Maximum Number of Particles in Air Federal Standard 209E
Class		Maximum Number of Particles in Air (particles per volume unit)
		Particle Size
		0.1 μm		0.2 μm		0.3 μm		0.5 μm		5 μm
SI	English	(m³)	(ft³)	(m³)	(ft³)	(m³)	(ft³)	(m³)	(ft³)	(m³)	(ft³)
M 1		350	9.91	75.7	2.14	30.9	0.875	10.0	0.283
M 1.5	1	1240	35.0	265	7.50	106	3.00	35.3	1.00
M 2		3500	99.1	757	21.4	309	8.75	100	2.83
M 2.5	10	12400	350	2650	75.0	1060	30.0	353	10.0
M 3		35000	991	7570	214	3090	87.5	1000	28.3
M 3.5	100			26500	750	10600	300	3530	100
M 4				75700	2140	30900	875	10000	283
M 4.5	1000							35300	1000	247	7.00
M 5								100000	2830	618	17.5
M 5.5	10000							353000	10000	2470	70.0
M 6								1000000	28300	6180	175
M 6.5	100000							3350000	100000	24700	700
M 7								10000000	283000	61800	1750

clean room classes and number size particles SI diagram

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 Federal Standard 209E is canceled and superseded by International Organization for Standardization (ISO) Standards - International Standards for Clean Rooms and associated controlled environments, ISO 14644.