NAS 1638

Do you know about Google?

Look here: http://www.practicingoilanalysis.com/article_detail.asp?articleid=409

I didn't know that NAS 1638 went to part 15! It will be pretty dirty fluid and definately not to be used for hydraulics!

Check out this site:-www.contractorsunlimited.co.uk/toolbox/hydraulicfluid.shtml

As you will see, NAS only goes to part 12. As a rough guide, hydraulic oil as supplied in a barrel from the refinery should be at part 9 and, dependent on system, should be cleaned to part 8 for standard system and part 6 if using an axial piston pump or motor. Even claner for servo valves!

NAS 15 is above the scale which runs from 1-12. The table below should help with interpreting these things. I found it at VibroNurse.com I figured since its in the free area I suppose its proabaly okay to post it here!!! VibroNurse also have a handy calculator which tells you what all the cleanliness standards actually mean and how to convert between them (www.vibronurse.com)

ISO 4406 is the European Equivalent of NAS 1638 (I guess they like to make things more complex over there!!!)

Anyway in answer to your question NAS 15 is off the scale!!!

Info. NAS 1638 "Cleanliness Requirements of Parts Used in Hydraulic Systems - Rev.3; Inactive for New Design After May 30,2001". Replaced by SAE AS 4059E