Guide to Cleanroom Classifications Manufacturers and Suppliers

In this era of technological advancements, there are critical factors related to the production of technical devices. One of the major issues is the control of miniscule elements that may upset the operation of a sensitive device. It is for this reason that Willis Whitfield developed and designed the first cleanroom in 1960. The design and purpose of a cleanroom is to keep outside environmental factors from contaminating any of its processes. A cleanroom classification is the level of cleanliness according to the size and quantity of particles per cubic volume of air. Classifications begin at ISO 1 and go to ISO 9. ISO 1 is the highest classification and is referred to as the cleanest possible environment while ISO 9 is the dirtiest. Most rooms fall into ISO 7 or 8. The main problems associated with keeping a cleanroom at the appropriate standards are the people who use the room and the items that are tested or constructed in it. Special controls are required to eliminate these problematic elements as much as possible.

The tables below give the various particulate density numbers and the Federal Standards 209E classifications. Note the micrometer reading for ISO 1 compared to ISO 9 where ISO 9 is normal room air.

International Organization of Standardization Particulate Standards

Class	maximum particles/m3						FED STD 209E equivalent
	>=0.1 µm	>=0.2 µm	>=0.3 µm	>=0.5 µm	>=1 µm	>=5 µm
ISO 1	10	2
ISO 2	100	24	10	4
ISO 3	1,000	237	102	35	8		Class 1
ISO 4	10,000	2,370	1,020	352	83		Class 10
ISO 5	100,000	23,700	10,200	3,520	832	29	Class 100
ISO 6	1,000,000	237,000	102,000	35,200	8,320	293	Class 1,000
ISO 7				352,000	83,200	2,930	Class 10,000
ISO 8				3,520,000	832,000	29,300	Class 100,000
ISO 9				35,200,000	8,320,000	293,000	Room Air

Federal Standards 209 E - Cleanroom Standards Classifications

	maximum particles/m3
Class	>=0.5 µm	>=1 µm	>=5 µm	>=10 µm	>=25 µm
Class 1	3,000		0	0	0
Class 2	300,000		2,000	30
Class 3		1,000,000	20,000	4,000	300
Class 4			20,000	40,000	4,000

The most obvious need for a contaminate-free environment is the pharmaceutical industry, where vapors or air pollutants could corrupt the manufacture of a medicine. Industries that produce intricate miniature circuits for precise instruments must be assured that the manufacturing and assembly is protected. These are only two of the many industries the use cleanrooms. Others are aerospace, optics, and nanotechnology. As miniaturization and scientific developments progress, cleanrooms are going to be more vital and important to manufacturing and production.

The most significant problem related to maintaining a cleanroom classification is the quality of the air circulating system. Though a cleanroom may have been classified as being in accordance with the specified standards, it can easily lose its classification by having a poor air filtration system, which depends a great deal on the number of filters required and the efficiency of the airflow system.

As with any manufacturing or scientific process, the major factor to be considered is cost, which is the most significant part of maintaining a cleanroom. In the planning of a cleanroom, and the class that is required, several dynamics need to be considered. It begins with the number of filters required to preserve the air quality of the room followed by the air conditioning system.

The design of the room has to be carefully studied so that it meets the requirements for its purpose. In too many cases, companies will ask for a cleanroom that is larger than what they require.