cleanroom

Room pressure differential is an important aspect in order to guarantee sufficient contamination control, but is difficult to control in airtight cleanrooms. This research uses simulation models to get an understanding and to quantify the room pressure controllability of airtight cleanrooms. The most influential parameters on the room pressure controllability are identified using a sensitivity analysis. The effects of the shell airtightness and overflow flowrates are quantified, and the effect of a flow/pressure cascade with three coupled rooms is investigated.

Investigations were carried out into the airflow in a non-unidirectional airflow cleanroom and its affect on the local airborne particle cleanliness. The main influence was the method of air supply. A supply inlet with no diffuser gave a pronounced downward jet flow and low levels of contamination below it, but poorer than average conditions in much of the rest of the room. A 4-way diffuser gave much better air mixing and a more even airborne particle concentration throughout the cleanroom.

The particle-free conditions provided by cleanrooms are vital for much of modern manufacturingindustry. There has been a substantial increase in the working environment of cleanroom. Specialgarments are therefore dressed in all cleanrooms to control particles and microbiological contaminationdispersed from personnel in cleanrooms. However, more tightly-woven fabrics of cleanroom garmentswill result in thermal comfort dissatisfaction. In this study, field tests of a cleanroom have been carriedout in our newly constructed MEMS laboratory.

The main purpose of this paper is to evaluate the main fluid mechanics parameters in the exit region of three different terminal systems commonly used for controlled environments such as clean rooms or operating theatres. Three different types of diffuser were tested i.e. a diffuser grid, a square ceiling diffuser and a swirling radial discharge diffuser. The paper presents results obtained experimentally which were carried out in order to study the flow characteristics of isothermal jets issuing from such devices.

A CFD model that incorporates fan-performance characteristics was applied to investigate and compare the air-recirculation performance of the two general designs of unidirectional-flow cleanrooms. For the simulation, typical flow-resistance models of the various components in the air path were used.

Comments about the project of the new french standard NF S 90-351 "Clean rooms and related controlled environments in medical establishments" and the consequences on the design approach of clean rooms to master airborne contamination are given.

The french standard NF S 90-351 has been modified to include a wider field of application. This standard now takes into account previsional aspects. It is needed to define "areas at risk", and materials and equipment performances.

In this paper, the variations of the airflow induced by a moving operator in a cleanroom installed with a curtain, are studied numerically. The effects of the moving operator and curtain on the airflow patterns are taken into account.

The National Institute of Health has conducted an extensive study on the issue of operating room ventilation system and its effect on protection of the chirurgical site. A CFD code using a finite-volume code was validated with experimental data.

A wall return and a ceiling return air arrangements of turbulent type clean rooms are presented in this paper. The influences of obstacles on the flow fields are compared by a numerical simulation.