Which of the following is not considered a component of hydraulic fluid contamination?

Hydraulic fluid contamination can significantly affect the performance and reliability of hydraulic systems. While many substances can contribute to contamination, airborne particles are not classified as components of hydraulic fluid contamination in the same way as the other options.

Water, for instance, is a common contaminant in hydraulic systems which can lead to corrosion, reduced lubrication effectiveness, and the formation of sludge or other harmful substances. Nonmetallic debris can include items like rubber particles or plastic fragments, which may come from seals and other components, negatively impacting the system's operation. Metallic debris, on the other hand, often arises from wear and tear of components within the hydraulic system, pointing to mechanical issues and leading to more rapid degradation of the fluid and system components.

Airborne particles, while they can settle into hydraulic systems, do not mix with the hydraulic fluid in the same way as the other contaminants. Their presence doesn’t result in the same chemical or physical effects on the hydraulic fluid itself, thus differentiating them from water, nonmetallic debris, and metallic debris that directly affect the fluid's properties and system performance.