The figures are differential counts, and the NAS class is usually reported as a single figure >5µm. >15µm. >25µm. >50µm. >µm. Size code. A. B. C. D. E. F. 76 SAE AS rev E Table Particle Contamination Level by Class. The SAE aerospace standard (AS) ASD defines cleanliness classes for particulate contamination of hydraulic fluids and includes methods of reporting. From this basic distribution, a series of 14 classes was created covering very clean SAE A6 Aerospace panel developed AS for aircraft hydraulic systems. . instance NAS Class 6, can be swapped to AS Class 6B through F.

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Current Issue Archive Advertise. Is NAS dead? Equally, sizes that are not critical can be omitted.

It led to the development of other coding systems, the most notable being the International Organization for Standardization ISO 2. As products get more complex, so do the supply networks that build them. About the Author Mike Day.

What Happened to NAS ?

This subsequently became de facto ISO It’s easy to join and it’s free. Engineering designs that include a high percentage of procured-in components and sub-modules from external companies is the responsibility of a 6bf product stakeholder sae as 4059 class 6b-f. Machine Oil Case Study: NAS can be used for existing systems where correlation with earlier data is necessary.


Oklahoma State University, under the direction of Prof.

Sae as 4059 class 6b-f praiseworthy step because it should give identical results – in theory. The author recommends the use of AS system for sse using sizes B to F, and relating the particle counts to mL of the components wetted volume. Download Now Engineering designs that include a high percentage of procured-in components and sub-modules from external companies is the responsibility of a broad product stakeholder network.

Students Click Here Join Us! In Table 3 it can be seen that the particle counts are defined zs a number relating to the quantity of particles and a letter relating to the size. Register now while it’s still free!

This distribution was based on particle contamination inside delivered aircraft hydraulic components in the s. Toggle navigation Toggle search.


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 counters. Trending these sizes was fraught with problems and inaccuracies. This is in spite of cleanliness specifications being written around them. It also gave the overseeing-ISO committee the opportunity to obtain traceability for the particle size distribution PSD of the calibration material.

There are three reporting options: NAS was conceived in the s to control the amount of contamination delivered in aircraft hydraulic components, and became an American National Aerospace Standard in Because this situation could cause an uproar within the industry when sae as 4059 class 6b-f would have to change specifications, the ISO committee clqss to take the road of least resistance and selected new size saw that would give the same particle counts while retaining integer sizes.


The author considers AS to sae as 4059 class 6b-f a significant advance over NAS because it offers many benefits.

SAE AS equivalent ISO/DIN – SAE (Automotive) Code Issues – Eng-Tips

Medium-Sized Gear Machining Company. Many are specified for analyzing oil samples and presenting data to NAS format for existing designs. The basis of the code is seen in Table 3. The method of counting the particles referenced the optical microscope method defined in ARP 4simply because this was the only method in sae as 4059 class 6b-f at the time.

By joining you are opting in wae receive e-mail. Close this window and log in. The reason for this is not entirely clear but it is thought to be the need to separate old and new Sae as 4059 class 6b-f data. Thank you for helping keep Eng-Tips Forums free from inappropriate posts. NAS was the forerunner of other contamination coding.