If a check of the existing filters reveals that this level of filtration is not present somewhere in the system, then either the level of filtration must be upgraded or the target cleanliness level must be revised downward. Filter beta ratios and their corresponding efficiency percentages are shown in Table 2. No coding system existed at the time for completed systems, so it was logical that it would be applied in this area. So how do you go about defining and achieving a fluid cleanliness level that optimizes hydraulic component life? Machine Oil Case Study:
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This principle is a feature of many of the classes that have ad since. Hydraulic filters are rated according to the size of the particles they remove and the efficiency with which they remove them.
What Happened to NAS ?
Once the minimum fluid cleanliness level required for acceptable component life in this system is established, the next step is to quantify the current cleanliness level of the fluid. Create your ss user feedback survey. The lack of traceability was a problem in the s as more companies endeavored to achieve ISO type quality systems.
If wear debris 40599 are above alarm limits, this usually indicates that a component in the system has started to fail.
It converts the particle counts at various size ranges into convenient broad-base classes. It was also embarrassing for laboratories involved with contamination testing which often had to explain why there was no traceability and control over the dust.
With contamination load minimized, the fluid flushed, and replacement filters of the appropriate blocking size and efficiency installed in the system, it is now possible to achieve the target cleanliness level.
Table 2 Filters are also commonly classified according to absolute or nominal ratings. If you obtain the latest issue of NAS you will find the following statements: Fact is, some level of particle contamination is always present in hydraulic fluid, even in new fluid. The most significant changes are:. National Aerospace Standard NAS 1 is a particulate contami-nation coding system used in the fluid power industry to simplify the commu- nication of data from particle saf.
As shown in Table 1, there is a correlation between the fluid cleanliness level and the level of filtration in the system. The accuracy, repeatability and speed of analysis allowed it to be used extensively for research into the effects of dirt on components and systems.
What Happened to NAS 1638?
Machine Oil Case Study: Toggle navigation Toggle search. However, users are encouraged to change to AS as soon as possible so that everyone is speaking the same language. Filter beta ratios and their corresponding efficiency percentages are shown in Table 2. Toggle navigation Toggle search. 0459
This concept gives AS much more flexibility than was possible with NAS because it is often the control of the cleanliness level that specifiers require rather than a fixed distribution; for example, they can specify improved control over critical sizes or relax controls over those that are not.
Medium-Sized Gear Machining Company. When to Use Fire-resistant Hydraulic Fluids. It involves a relentless cycle of fluid sampling and remedial action ssae necessary to ensure the appropriate fluid cleanliness level is continuously maintained. This was based upon the size distribution of A.
Keep in mind that particle contamination can be generated internally or ingested from external sources.
Difference between NAS Class and SAE AS | Noria Message Boards
It is widely accepted that particle contamination reduces the service life of hydraulic components. A praiseworthy step because it should give identical results - in theory. Machine Oil Case Study: How to Ensure Hydraulic System Reliability. This subsequently became de facto ISO Beta ratio is the number of particles, at the given size, that enter the filter divided by the number of particles that pass through the filter. It also gave the overseeing-ISO committee the opportunity to obtain traceability for the particle size distribution PSD of the calibration material.
About the Author Brendan Casey. The next step is to change all of the filters ax the system.