This part of ISO 16232 defines the vocabulary used in the characterization and measurement of particulate contamination of parts, components, sub-assemblies and assemblies constituting the fluid circuits of internal combustion engines of road vehicles. This applies to all components that may come into contact with a liquid (e.g. oil, fuel, air conditioning refrigerant, coolant), a solid lubricant or a gas (intake air). Unless otherwise specified, this International Standard deals with particulate cleanliness only. It does not therefore cover appearance defects or contamination by liquid or gas materials. It covers the amount and the nature of residual particulate contaminants resulting from the whole manufacturing processes and from the environment.