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Issue 32: October 2017

Main feature

Methods to keep a product clean

Koos Agricola

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Abstract

Contamination control concerns methods to keep a product clean. For this reason the cleanliness of the surface of a product is expressed in terms of particles and also chemicals. Products can be contaminated by deposition or contact transfer. Deposition depends on the concentration of particles in the air and their deposition velocity. Large particles have a high deposition velocity and their concentration depends on the way the cleanroom is used. Smaller particles have a low deposition velocity and their concentration depends on the airflow. Another contamination mechanism is by contact with dirty surfaces, these having been previously contaminated by deposition. Chemical substances can condense or adsorb onto surfaces or they can be transferred by contact. Contamination control solutions include the provision of a controlled environment that is kept clean by flushing with filtered air and by regular cleaning of all surfaces. The most commonly used ventilation system is dilution with non-unidirectional airflow. Higher grade cleanrooms operate by displacement with unidirectional airflow. Classification of cleanrooms in accordance with ISO 14644-1:2015 is briefly described including the treatment of macroparticles with a threshold size between 5 μm and 20 μm. Surface contamination by particles that can be even larger is covered by ISO 14644-9:2012 and chemical contamination by ISO 14644-10:2013. A section on risk assessment with respect to particles introduces the concepts of particle deposition rate (PDR) and latitude. Latitude is the process window between the initial surface concentration and the final acceptable surface concentration. These concepts are illustrated by a worked example. PDR measurement methods are described, then how to establish control, how to treat process equipment and how to demonstrate control.

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Standards

Understanding ISO 21501-4

Daniele Pandolfi, Steve Kochevar

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Abstract

In order to ensure accuracy in air monitoring data, optical particle counters must be regularly calibrated according to ISO 21501-4 requirements. Flow rate, counting efficiency, resolution, false count rate, and particle size error are key parameters of calibration, in addition to coincidence loss, maximum particle concentration, sampling time and response rate. Verifying that these parameters are within specified limits is essential for maximizing the potential of an optical particle counter in a cleanroom environment.

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Regulatory reflections

Revisions made to European Pharmacopoeia sterilisation chapters

Tim Sandle

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Abstract

Methods of sterilisation and the assessment of sterilisation using biological indicators represent important areas of regulatory concern. The two applicable guidance chapters in the European Pharmacopeia have undergone revisions. This article assesses the main changes. Notably these include reference to the production of sterile products through aseptic processing for the first time; and changes to the assessment of the suitability of biological indicators, including a new recommendation for supplier auditing.

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Conference report

Cleanroom Technology Conference 2017 – a review

Susan Birks

News

The future is bright at Crowthorne Hi-Tec Services with new offices and new product offerings

Particle Measuring Systems releases new LiQuilaz® II Particle Counter

Nitritex explains the changing face of EN374 and cleanroom gloves

Cherwell delivers bespoke environmental monitoring solutions

Multiple new records created at Cleanroom Guangzhou 2017

CRC completes multimillion-pound cleanroom suite

Events and Training courses

Life-lines