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Issue 52: 2024/Number Three

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Determining the required air supply rate to maintain airborne cleanliness levels in pharmaceutical cleanrooms using a scientific approach

N D Lenegan and T Eaton

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Abstract

This paper details a scientific approach to determine the air supply rate required to attain specified concentrations of airborne particulate and microbial contamination, in non-unidirectional airflow cleanrooms. It applies the methodology described in published technical papers and compares this with the more traditional approach based on typically utilised air change rates.

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Calculation of concentrations of airborne contamination and required air supply rates in non-UDAF cleanrooms

W.Whyte, University of Glasgow, UK

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Abstract

This article discusses information given in a series of scientific papers written by the author and his co-authors, to assist in the design of non-unidirectional airflow (non-UDAF) cleanrooms. These papers explain how scientific principles can be used to calculate (a) the concentrations of airborne contamination likely to be found in a non-UDAF cleanroom, and (b) the air volume supply rates required for a desired level of airborne cleanliness. Also discussed is the calculation that relates air change rates to the required recovery rate from high concentrations of airborne contamination. Various factors are considered that will influence the accuracy of these calculations, such as the rate of dispersion of airborne contamination in the room, ventilation effectiveness, surface deposition of larger particles and microbe-carrying particles, and the contribution of clean air separative devices. Guidance is also provided on how to obtain the necessary values of the factors used in the calculations.

The papers discussed in this article are listed at the end of this article,and can be freely downloaded and consulted from the Enlighten database at the University of Glasgow.

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Particle losses in sample tubing and how to validate them

Jason Kelly

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Abstract

This paper investigates particle losses in sampling tubing used with particle counters in cleanroom environments, emphasizing the significance of data quality and compliance with ISO/TR 14644-21. It addresses the challenges posed by particle losses in sample tubing, particularly for particles ≥5.0μm. The study explores the impact of tubing diameter, length, and bends on particle loss, with tests revealing significant improvements when using larger diameter tubing. For instance, increasing tubing from 1/4" to 3/8" reduced particle loss for 5.0μm particles from 73% to 30%. The findings highlight the need for optimal tubing configurations, including shorter and straighter paths, to minimize particle losses. The paper underscores the importance of adhering to best practices and standards to ensure accurate and reliable particle count data, crucial for effective contamination control in cleanroom environments.

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Is your HEPA filter working properly?

Philip van Beek

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Abstract

Filtration is an important parameter in the operation of your cleanroom and makes an essential contribution to the quality of the supply air to the cleanroom. How do you know it is working properly? As well as the qualification test in the factory to ISO 29463-1:2024 or EN1822, depending on where you are located in the world, you also need to carry out an in-situ test of the filter system to ISO 14644- 3:2019 after installation. Is it leak-free? Is the in situ leak test performed correctly? This article gives you information on the testing of your cleanroom filtration system to ensure that the cleanroom performs to specification, and on training accredited by the CTCB-I (Cleanroom Testing and Certification Board – International) so your test engineers can be certified to carry out the testing.

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Book review

Advances in Cleanroom Technology, Second Edition by William Whyte

Reviewed by John Neiger

Symposium: ISCC'24

Milan to host landmark 26th International Symposium on Contamination Control

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