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OPIA (Operaciones e Ingeniería de Avanzada de Centroamérica S.A.) deliver specialised engineering services in cleanroom testing, validation and onsite automated air quality monitoring systems. The end customer was a large medical device company based in Costa Rica.
For medical companies to ensure their products meet quality standards, air quality is paramount. Recently, a large medical company experienced a number of air quality events associated with excursions in viable particle counts within a cleanroom. As a result, the company suffered costly lost production, downtime and cleaning expenses. They required detailed information to identify the root cause of the events and provide feedback on potential remedial solutions.
The Cleanroom must consistently comply with the established requirements in the current edition of the ISO-14644-1 standard for the class ISO-8 for non-viable particle count and the established limits for viable particle counts as per customer requirements. In addition to the regular verifications conducted as per customer requirements (such as Air Changes/Hour, Differential Pressures, HEPA Filters Leak testing, Temperature, Relative Humidity and Airflow Visualization in Return Intakes), OPIA required supplementary and more detailed analyses:
- Spatial distribution verification of the non-viable particle counts in several particle sizes as a leading indicator of potential focus areas on the viable particle counts.
- Detailed computational fluid dynamics (CFD) analysis to deepen the understanding of residence times, airflow streams and performing a cross-analysis with the viable particle counts focus areas, in an effort to identify key contributors to the excursions.
OPIA chose Matrix to build a CFD model of the cleanroom. Matrix has the specialised experience required to conduct cleanroom simulations. Utilising the world’s most comprehensive CFD solution, STAR CCM+, Matrix can not only perform advanced analysis but presents solutions to prevent recurrence of air quality events.
OPIA performed flow tests on all the air supplies and returns, which confirmed that the model was simulating actual flow conditions in the room. The CFD model was used to calculate velocities and pressures within the room and most importantly the air residence time. This led to the identification of the location of critical dead zones within the room where non-viable particles are likely to settle. A particle tracking multiphase simulation was also performed to help OPIA engineers understand how particles of different sizes would be transported throughout the cleanroom so that accurate decisions could be made to re-design the layout and flow rates of air supplies.
The CFD model developed by Matrix was able to identify the critical region within the cleanroom. Strong agreement was observed between the location of high residence time areas and non-viable particle counts as measured by OPIA. Matrix provided practicable recommendations to improve air-flow within the cleanroom. As a result, the medical company has eliminated air quality events, preventing losses estimated in the range of hundreds of thousands of US $ per year in production under quarantine, extraordinary cleaning processes of the cleanroom and the associated impact on the regular operation of manufacturing operations.
Residence time prediction by Matrix
Spatial (2 dimensions) Non-viable particle count map in cleanroom (measured by Opia) at 0.5 µm and above/m3.