Cleanroom

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Image:Clean room.jpg A cleanroom is a manufacturing environment that has a low level of environmental pollutants such as dust, airborne microbes, aerosol particles and chemical vapors. More accurately, a cleanroom has a controlled level of contamination that is specified by the number of particles per meter-cubed and by maximum particle size.

1 Overview
2 Cleanroom classifications
3 See also
4 External links

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Overview

Cleanrooms can be very large. Entire manufacturing facilities can be contained within a cleanroom with factory floors covering thousands of square meters. They are used extensively in semiconductor manufacturing, biotechnology, the life sciences and other fields that are very sensitive to environmental contamination.

The air entering a cleanroom from outside is filtered to exclude dust, and the air inside is constantly recirculated through high efficiency particulate air (HEPA) and ultra low penetration air (ULPA) filters to remove internally generated contaminants. Staff enter and leave through air locks (sometimes including an air shower stage), and wear protective clothing such as hats, face masks, boots and cover-alls. Equipment inside the cleanroom is designed to generate minimal air contamination. Common materials such as paper, pencils, and fabrics made from natural fibers are often excluded. Low-level cleanrooms are often not sterile (i.e., free of uncontrolled microbes) and more attention is given to airborne particles. Particle levels are usually tested using a particle counter.

Some cleanrooms are kept at a higher air pressure so that if there are any leaks, the air rushes outside. This is similar to the lower pressure used in biological hot zones to keep the microbes inside.

Cleanroom HVAC systems often control the humidity to low levels, such that extra precautions are necessary to prevent electrostatic discharges.

Entering a cleanroom usually requires wearing a cleanroom suit.

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Cleanroom classifications

The following is adapted from Rockwell Automation:

The cleanroom standards tables indicate the maximum number of allowable particles of the indicated size per cubic foot (for US FED) or cubic meter (for ISO) for each class.

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US FED STD 209E cleanroom standards

particle/ft³
Class	0.1 µm	0.2 µm	0.3 µm	0.5 µm	1 µm	5 µm
1	35	7	3	1
10	350	75	30	10	1
100	3500	750	300	100	10	1
1,000				1,000	100	10
10,000				10,000	1,000	100
100,000				100,000	10,000	1,000

NOTE: US FED STD 209E was canceled November 29, 2001. Reference: http://www.iest.org/publctns/fedstd209.htm

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ISO 14644-1 cleanroom standards

particle/m³
Class	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
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	293
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