Image analysis methods are compared for detecting particulates

By Monique Dallaire, Clemex Technologies inc.

The quantitative determination of particulate contamination is of prime importance for assessment of cleanliness in various environments from air in cleanrooms to hydraulic fluids in mechanical components.

Manufacturers and quality control labs are finding it increasingly essential to guarantee the purity and uncontaminated state of components and fluids. Diverse industries depend on particle analysis measurements that are both reliable and reproducible. Information this critical must be delivered through proper documentation that is customized to the specific requirements of the internal audience and to industry standards; in this application the ISO 4407 standard was used.

The analysis process of paper filter residue is simple: Fluids, such as oils or solvents, are filtered through a circular membrane. The collected residue is caught by the filter. One method commonly utilized to observe particulate contamination is counting and measuring particulates collected on filters using optical microscopy. In quality control laboratories, automated image analysis allows the user to save time and money as well as eliminate subjectivity due to fatigue. The challenge of automated image analysis is detecting particles of different reflectivity and fibers whose length exceeds the field of view, within a reasonable amount of time.

Once the particles and fibers are detected accurately, the particulate contaminants are separated from the fibers and are classified by size and/or color.

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