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Cleanroom Classifications

  • 2022-03-02
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CLEANROOM CLASSIFICATIONS

(ISO 8, ISO 7, ISO 6, ISO 5)

 

CLEANROOM CLASSIFICATIONS

Cleanrooms are classified according to the cleanliness level of the air inside the controlled environment. The clean room class is the level of cleanliness the room complies with, according to the quantity and size of particles per cubic meters of air. The primary authority in the US and Canada is the ISO classification system ISO 14644-1.

This ISO standard includes these clean room classes : ISO 1, ISO 2, ISO 3, ISO 4, ISO 5, ISO 6, ISO 7, ISO 8 and ISO 9. ISO 1 is the “cleanest” class and ISO 9 is the “dirtiest” class. Even if it’s classified as the “dirtiest” class, the ISO 9 clean room environment is cleaner than a regular room.

The most common ISO clean room classes are ISO 7 and ISO 8. The Federal Standard 209 ( FS 209E ) equivalent for these ISO classes are Class 10,000 and Class 100 000.

The old Federal Standard 209E ( FS 209E ) includes these clean room classes : Class 100,000; Class 10,000; Class 1,000; Class 100; Class 10; Class 1. This standard was replaced in 1999 by ISO-14644-1. It was withdrawn in 2001, but it is still widely used.

Clean rooms must also follow industry-specific and international standards. For example, EU GMP (A-B-C-D), applies to pharmaceutical products and USP (795, 797 and 800) to compounding pharmacies.

You might also like this article —>How Classification Impacts your Cleanroom Design

Want to learn more about Clean Rooms? —>What is a Clean room?

ISO CLEANROOM STANDARDS AND LAYOUTS

Depending on the class of clean room system you would like to reach, it is important to allow for enough square footage. This is critical not just for the clean zone, but also for the airlocks/gowning room which prevent the migration of particles from outside into the clean space.

The rule of thumb is that you should not skip over more than one class when you move towards a cleaner room (for example, from ISO 7 to ISO 6, not from ISO 8 to ISO 6), as illustrated below. In reality, however, you can reach a cleaner class with fewer airlocks than described below with the appropriate air changes per hour.

This depends on the process taking place inside the cleanroom, the size of the cleanroom, the number of people working inside, the equipment inside, etc. Seek the help of a cleanroom expert who can create the optimal layout for your particular needs.

Already in the design process of your cleanroom? Contact us to give a jump start to your cleanroom project!

ISO 8 CLEANROOM (CLASS 100,000 CLEANROOM)

Let’s assume that an unclassified space (office or lab) is ISO 9. In this case, you can directly enter an ISO 8 cleanroom, without an airlock. Depending on the production process inside the cleanroom, however, you may have to add a gowning room.

ISO 8 zone | 15–25 air changes per hour

Non-unidirectional air flow

ISO 7 CLEANROOM (CLASS 10000 CLEAN ROOM)

This is one of the most common classes of cleanrooms. If you need an ISO 7 cleanroom, you should consider having an ISO 8 airlock/gowning room prior to entering the ISO 7 room. The air changes per hour will vary in both rooms as described below.

ISO 7 zone | 30–60 air changes per hour

ISO 8 zone | 15–25 air changes per hour (ante-room)

Non-unidirectional air flow

ISO 6 CLEANROOM (CLASS 1,000 CLEANROOM)

In theory, for an entire room to reach ISO 6 air cleanliness, you need to enter the cleanroom via an ISO 8 (ante-room), then go through an ISO 7, to finally get into the ISO 6, as shown in the image.

In reality however, you can reach an ISO 6 cleanroom with 1 (recommendation is 2) airlock. Again, it depends of the size of the room, the process taking place inside the cleanroom, the number of people working inside, the equipment inside, etc.

Unidirectional air flow is sometimes recommended to reach ISO 6 classification. For a room of less than 4–6 meters in width (depending on the activities taking place inside the cleanroom), air returns can be positioned on the side of the walls instead of in the floor. Installing air returns in the floor is more expensive.

ISO 6 zone | 90–180 air changes per hour

ISO 7 zone | 30–60 air changes per hour

ISO 8 zone | 15–25 air changes per hour (ante-room)

ISO 5 CLEANROOM (CLASS 100 CLEANROOM)

In theory, for a classified room (not just below a LAFW hood) to reach ISO class 5 air cleanliness, you need to enter the cleanroom via an ISO 8 (ante-room), then go through an ISO 7, followed by an ISO 6 to finally get into the ISO class 5 cleanroom.

In reality, however, you can reach an ISO 5 cleanroom with 2 or 3 airlocks. The optimal layout depends on the process taking place inside the cleanroom, the size of the room, the number of people working inside, the equipment inside, etc.

In addition, an ISO 5 or class 100 clean room needs to use unidirectional air flow. Unidirectional air flow cleanrooms use much more air than non-directional air flow cleanrooms. High efficiency filters are installed across the entire ceiling.

The filtered air sweeps down the room in a unidirectional way, at a velocity generally between 0.3 m/s and 0.5 m/s, and exits through the floor, removing the airborne contamination from the room. Cleanrooms using unidirectional air flow are more expensive than non-unidirectional ones, but can comply with more stringent classifications, such as ISO 5 or lower.

ISO 5 zone | 240–360 air changes per hour

ISO 6 zone | 90–180 air changes per hour

ISO 7 zone | 30–60 air changes per hour

ISO 8 zone | 15–25 air changes per hour (ante-room)

COMPARISON BETWEEN SELECTED EQUIVALENT OF FS 209E ( FED STD-209E ) AND ISO 14644-1

ISO 14644-1FS 209E
ISO 3Class 1
ISO 4Class 10
ISO 5Class 100
ISO 6Class 1,000
ISO 7Class 10,000
ISO 8Class 100,000


CLEAN ROOM CLASSIFICATION PARTICLE CONCENTRATION

The basis of clean room standards is the micrometer, or micron for short (µm), which is the size of the particles to be filtered. As stated before, clean rooms are classified by how clean the air is, according to the number of particles and size of particles per volume of air. The clean room classification table below shows the maximum concentration limits (particles/m3 of air) for particles equal to and larger than the considered sizes shown.

Some classifications do not require certain particle sizes to be tested because the respective concentrations are too low or too high to be tested, but they should not be zero.

ISO CLEAN ROOM STANDARDS AND THE FS 209E EQUIVALENT

ISO 

Class

Class Maximum Particles/m³Particles/ft³FS 209E Equivalent
≥0.1µm≥0.2µm≥0.3µm≥0.5µm≥1µm≥5µm≥0.5µm
ISO 110 






ISO 21002410




ISO 31,00023710235

1Class 1
ISO 410,0002,3701,02035283
10Class 10
ISO 5100,00023,700102,003,52083229100Class 100
ISO 61,000,000237,000102,00035,2008,3202931,000Class 1,000
ISO 7


352,00083,2002,93010,000Class 10,000
ISO 8


3,520,000832,00029,300100,000Class 100,000
ISO 9


35,200,0008,320,000293,000

** Old FS 209E classes were calculated in particles per cubic foot, whereas ISO classes are in cubic meter of air.

Design Requirements for Cleanroom Classifications

CriteriaClass 10 ISO4Class 100 ISO5Class 1000 ISO6Class 10,000 ISO7Class 100,000 ISO8
Air Changes Per HR/Min500-600 / 8 to 10300 to 480 / 5 to 8180 / 360 /120 /0.33
Filter Coverage %90 – 10060 – 7020 – 307 – 154  – 5
CFM Per Square foot85 – 9036 – 6518 – 329 – 164 – 8
Filter Efficiency99.9997% ULPAs99.997% ULPAs99.997% ULPAs99.997% ULPAs99.97% ULPAs
Ceiling TypeAluminum T-bar gridAluminum T-bar gridAluminum T-bar gridConventional T-bar gridConventional T-bar grid
Light Fixture TypeTear drop or Flow thruTear drop or 2'x4' cleanroom fixture2'x4' cleanroom fixture2'x4' cleanroom fixture2'x4' standard fixture
Ceiling PanelFRP, Vinyl rock or MylarFRP, Vinyl rock or MylarVinyl rock or MylarVinyl rock or MylarVinyl rock or Mylar
Wall SystemModular or standard builtModular or standard builtModular or standard builtModular or drywallModular or drywall
Flooring CoverWelded sheet vinyl or EpoxyWelded sheet vinyl or EpoxyWelded sheet vinyl or EpoxySheet vinyl or VCTSheet vinyl or VCT
Flooring Base2” to 6” coveCove or Aluminum base channelCove or Aluminum base channelCove or Aluminum base channelCove or Aluminum base channel
Air ReturnsRaised floor or center returnsLow wall on long axisLow wall at perimeterLow wallLow wall or ceiling


To learn more about Cleanroom Classifications, check out this article《FAQs About Cleanroom Classifications

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