Cleanrooms 101

What is a Cleanroom?

A cleanroom is a special environment that is supplied with HEPA (high efficiency particulate absorption) or ULPA (ultra-low particulate air) filtered air. It is designed to meet the cleanliness class requirements of the manufacturing or testing process. The cleanroom can be designed as a single ball room or it can be divided into as many individual rooms as required. Cleanroom construction varies from hardwall, rigid clear wall or soft wall construction (reference cleanroom types, this web site). A cleanroom is not “a cleaning machine”; operating protocols, cleaning and maintenance are required for the cleanroom to function as designed. Cleanroom surfaces and surfaces of equipment used in the cleanroom should be as smooth as possible for effective cleaning. Medical and pharmaceutical cleanrooms have additional requirements where all seams will be sealed to prevent harboring of pathogens. The rooms are designed and environmentally controlled to minimize airborne contamination from contacting critical sites. These facilities shall also provide a comfortable and well-lighted working environment, which typically includes a temperature of 68° F to 72° F to maintain a comfortable working environment for personnel.

Access to the cleanroom should be limited to personnel trained and authorized to work in and maintain the area. To minimize process and product contamination the cleanroom should be setup as follows:

ISO Example

Gowning Area / Ante Room: This is where the personnel will put on the specified cleanroom garment that will range from a smock, bouffant, face mask, gloves and shoe covers to a full bunny suit, hood and booties. The extent of gowning will be determined by the process requirements.

When entering the Gowning Room / Ante Room the cleanroom air will hit you in the face due to the increased pressurization of the room in relation to the non-cleanroom outside area. The cleanliness level of this area will generally be less than the other cleanroom areas.

The Manufacturing / Process area: This is where the product is built or where testing is performed. This area is generally built at a higher level of contamination control than the gowning room and is at a higher pressure level than the gowning room. This means that when you open the door from the Gowning Room to the process area the cleanroom air hit you in the face. Levels of protocol are higher in this area that will include frequency of cleaning, restrictions on allowable equipment and tools and controlled product transfer in and out.

Critical process area: If a part of the cleanroom process required a higher level of contamination control an additional room can be added or a vertical or horizontal flow bench (reference flow benches, this document) can be incorporated. Again this area will be of a higher pressure than the adjoining areas.

Negative Flow Rooms: Negative air pressure is used in cleanrooms where the goal is to keep any possible contamination from escaping the cleanroom. Windows and doors have to be completely sealed, and internal air is exhausted to “ambient” or outside of the Facility through filters or scrubbers. In general air outside the cleanroom is likely to flow into the negative pressure room rather than out of it.

The physical characteristics of construction: walls, floors, fixtures and ceilings should be smooth, impervious and free of cracks, crevices and be non-shedding. Surfaces should also be resistant to damage from cleaning and sanitizing agents. For certain industries, wall to wall and wall to ceiling junctures should be coved and / or caulked and ceiling panels, light troffers and filter units should be caulked in place to eliminate any seam. Walls may be panels locked together and sealed, reference CZT I Hardwall, floors can be Epoxy or similar material coating or overlaid with sheet vinyl flooring with heat-sealed seams. Both floor covering systems should incorporate floor to sidewall coving to a minimum of 4”.

We also offer the CZT IV Cleanroom built with clear Polycarbonate or Acrylic wall panels. The CZT IV cleanroom design allows it to be used as a totally free standing room, or in a combination with your existing walls. The CZT IV is specifically designed to meet requirements of a wide range of industries including the medical, pharmaceutical, parts cleaning, electronic, disk drive. The CZT IV can be set-up to meet ISO Class 5 (Class 100) through ISO Class 8 (Class 100,000) and can be divided into as many individual rooms as required. The cleanroom can be equipped with single or double doors, strip curtains and standard or custom sized Pass-Thru Boxes. Each Aluminum CZT IV is completely factory prefabricated to minimize on-site installation time. All components are furnished. All you have to do is supply electricity and A/C. The CZT IV is demountable and can be easily relocated in another section of your site or another part of the country. Average installation time is 2 to 3 days from start to certification (depends on overall size).

If cleanliness is the only concern please look into our CZT III Modular Softwall Cleanroom that is our most economical room design. The CZT III is designed to meet requirements of a wide range of industries including the parts cleaning, electronic, clean packaging to name a few. It is our experience that the CZT III will be moved from one product line to another as required. The softwall cleanroom is totally freestanding or it can be used in combination with your existing walls and ceiling. The room comes in varying heights to 16’ and can be equipped with an internal or external Gowning Room. The modularity of the cleanroom is also enhanced with the addition of locking caster.

ISO Classification of Particulate Matter in Room Air

Limits are in particles of 0.5 µm and larger per cubic meter [current ISO] and cubic feet [former Federal Standard No. 209E].

Class Name Partical Count
ISO Class US FS 209E ISO, m³ FS 209E ft³
3 Class 1 35.2 1
4 Class 10 352 10
5 Class 100 3,520 100
6 Class 1,000 35,200 1,000
7 Class 10,000 352,000 10,000
8 Class 100,000 3,520,000 100,000

Adapted from former Federal Standard No. 209E, General Services Administration, Washington, DC, 20407 (September 11, 1992) and ISO 14644-1 : 1999, Cleanrooms and associated controlled environments— Part1: Classification of air cleanliness. For example,3,520 particles of 0.5 µm per m3 or larger (ISO Class 5) is equivalent to 100 particles per ft3lent to 100 particles per ft3 (Class 100) (1 m3 = 35.2 ft3)


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