Clean room

A clean room is a part or a series of parts where the particulate concentration is controlled in order to minimize the introduction, the generation, retention of particles inside. The parameters such as the Temperature, the moisture and the relative pressure are also maintained on a precise level. (definition according to the ISO standard 14644-1)

Utility

The clean rooms are used in the fields sensitive to the environmental contaminations: Manufactoring process of the transistors, the Biotechnology S and other fields of the Biology, the construction of space engines, the construction of optics or micromecanisms, in the hospitals for the Operating room suite S or of Bacteriology.

In these fields, the handled objects have sizes about the Micromètre or nanometer and the particles present in the air not purified can be much larger and be fixed above. In addition, the chemical or bacteriological experiments carried out can be dangerous for the man or the environment. This work is likely to be sensitive to the variations of pressure, temperature, moisture or with the presence of gas or chemical vapors. Lighting can be also controlled for the operations sensitive to the Ultraviolet S like the Photolithographie, to the Infrarouge S or certain frequencies of the luminous Specter for optics…

Operation

The air entering the clean room can be filtered according to various levels of sizes of undesirable elements; dust, until faces of thirty times lower than an human cell. To limit the filling of the filters prematurely (Technical and aeraulic filtering), the return air in low point in the room (aspiration), is filtered again in a Centrale of treatment of air (CTA) then returned in the room (time Taux of mixing), most of the time by the top. This flow of air recycled top to the bottom renews the total volume of air of the room up to 60 times per hour. Lastly, to avoid the concentration of CO₂ (a scientist consumes also oxygen and rejete of CO₂) and to compensate for the openings of doors of the clean room, approximately 30% of new air are added each hour (time Renewal rate), filtered according to a process similar to recycling. Certain zones are into 100% new air…

It is necessary to then differentiate two great types of rooms:

rooms in overpressure compared to the atmospheric pressure to prevent that various pollutants (dust, bacteria…) can enter that one finds mainly in the drug company and electronics

rooms in depression compared to the atmospheric pressure to prevent that various contaminants (Virus, Bacteria, Spore S,…) cannot leave, in this case the foul air extracts, passes through a high efficiency Filter before being evacuated towards outside. (example P4 laboratory in LYON)

The entry and the exit are done via one or several hoppers, sometimes equipped with a shower with air or water, and cloakrooms. Indeed, the human body produces an significant amount of contaminant products like the hairs, the hair, the cells of died skin,… Therefore the operators who evolve/move in the clean room must be vêtus of more or less important equipment according to the degree of contamination and tolerated dust contamination. The equipment can comprise a combination, one covers hair (cap), of the gloves, of the slippers, a mask, specific underclothing, see a complete diving-suit.

The tools used inside are selected to produce less particles possible.

Classification of the clean rooms

The element most important is the quantity of dust per unit of volume and it is the only parameter controlled for certain clean rooms with the more flexible criteria.

One classifies the clean rooms according to the number of particles per unit of volume. The traditional standard US EDF STD 209E used the cubic feet but it is replaced by the standard ISO 14644-1 expressed in cubic meters which corresponds to the European standard.

All these measurements are done using a measuring device: The radiation counter which will count the number of particle in a given volume and thus will determine the class of your clean room.

Standard ISO 14644-1

What it is necessary to retain:

Classify ISO 3 = Classe 1 according to FS 209

Classify ISO 4 = Classe 10 according to FS 209

Classify ISO 5 = Classe 100 according to FS 209

Classify ISO 6 = Classe 1000 according to FS 209

Classify ISO 7 = Classe 10000 according to FS 209

Classify ISO 8 = Classe 100000 according to FS 209

This European standard cancels and replaces standard NFX 44-101

See too

Internal bonds

Manufactoring process of the transistors

External bonds

BPF in hospital/pharmaceutical medium

Organization A3P: http://www.a3p.org/?lg=fr
ASPEC: http://www.aspec.asso.fr/

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