What is the NAS test and why is it important for special hydraulic oils?
Posted by Hamid Shakouri on 3rd Sep 2024
Within the realm of oil analysis, the NAS (National Aerospace Standard) system serves as a tool for assessing particulate contamination levels in the oil. This metric becomes an indicator of potential wear and damage within machinery. The NAS system assigns a cleanliness code to the oil, considering the quantity and size of particles present per unit volume of fluid.
The NAS code is determined by counting particles in the oil that exceed specified size thresholds, often set at 5, 15, or 25 microns. The combined particle counts within each size range are then used to calculate the NAS code, ranging from 0 to 12. In essence, a higher NAS code indicates greater contamination levels in the oil.
The NAS system finds widespread application in the aviation and aerospace industries, along with other sectors dependent on hydraulic systems and lubricated machinery. Its primary role is to monitor fluid conditions and identify potential issues proactively, helping to address concerns before they escalate into more severe problems.
Understanding the NAS Table
- Particle Size (Microns): The table categorizes particles by their size, measured in microns (µm).
- Maximum Particles per 100 ml: This column indicates the maximum number of particles allowed in a 100 ml sample for each size category.
The NAS code is essential for determining the cleanliness of fluids, as contamination can significantly impact the performance and lifespan of hydraulic systems and other equipment. The lower the NAS code number, the cleaner the fluid.
