Final answer:
Special purpose cleaners containing phosphates or industrial-strength cleaners with quaternary ammonium compounds are used in dye penetrant inspections to ensure surfaces are free of contaminants.
Step-by-step explanation:
When performing a dye penetrant inspection, a special purpose cleaner is typically used to ensure that the surface of the material is free of contaminants that could interfere with the inspection process. These special cleaners often contain detergents with phosphates for breaking down organic compounds and may include industrial-strength cleaners containing quaternary ammonium compounds, which serve as effective disinfectants. It is vital to use the appropriate cleaner to ensure that the dye penetrant provides accurate results by entering into any defects without being impeded by dirt, grime, or grease. For ferrous metals, cleaners with chelating agents such as citric or phosphoric acids and surfactants are used.