LONDON A new BSI Standard – BS EN ISO 14664-8:2006 – has been released covering cleanrooms and associated controlled environments.
Within this part of BS EN ISO 14644, the presence of airborne molecules is expressed as airborne molecular contamination (AMC). Molecular contamination is a three-step event. The first step is generation due to external sources, process leakage or construction or human material outgassing. The second step is transport as AMC in air. The third step is sorption on the sensitive surface, which can be quantified as a surface molecular contamination (SMC).
Classification is in terms of airborne concentrations of specific chemical substances (individual, group or category). It provides a protocol to include test methods, analysis and time weighted factors within the specification for classification.
BS EN ISO 14644-8:2006 is one of a series of standards concerned with cleanrooms and contamination control. Many factors besides AMC need to be considered in the design, specification, operation and control of cleanrooms and other controlled environments and these are covered in some detail in other parts to the standard.