A laboratory analysis of a hydraulic fluid sample reveals a high count of particles in the 5 to 15 micron range along with trace amounts of ferrous metal particles. This level of contamination is most significant to a technician because it can lead to:
- AAn increase in the fluid's fire point and flash point
- BErosion and premature wear of close-tolerance components such as servo valves and pump pistons
- CA decrease in the fluid's viscosity index at low temperature
- DDirect evidence that the reservoir standpipe has failed
Show answer & explanationAnswer & explanation
Correct answer: B. Erosion and premature wear of close-tolerance components such as servo valves and pump pistons
Contaminant particles in the 5 to 15 micron range are within the clearance tolerances of critical hydraulic components like servo valves, pumps, and actuators. Over time, these particles cause abrasive erosion and scoring of precision-fitted surfaces, leading to leakage, sticking, or premature failure. Metal particles in particular can indicate active internal wear already occurring within a pump or actuator.
Why the other options are wrong
- A. Particle contamination does not affect the fluid's flash or fire point characteristics.
- C. Viscosity index relates to the fluid's chemical formulation, not particulate contamination.
- D. A standpipe failure would allow air entrainment or fluid starvation, not particulate contamination specifically.
Hydraulic Fluid Contamination Analysis
Laboratory particle counting of hydraulic fluid identifies solid contaminants that can abrade close-tolerance components like servo valves and pump pistons, leading to premature wear and failure.
- Particles in the 5-15 micron range match critical component clearances
- Ferrous metal particles suggest active internal component wear
- Regular fluid sampling supports condition-based maintenance
Memory trick: Tiny grit in tight gaps grinds parts to dust