Filter Rating for Cleanliness Level of NAS 3

mansilakhani I am not a filtration expert and I am sure there are some out there that will give you a better answer and or correct this one.

This NAS standard 1638 to the best of my knowledge has been superseded by SAE 4059 or the more commonly (I think) used ISO 4406 for fluid power.

As per NAS 3 your are looking to keep particle count of >1 micron below 6520. SAE states 6520 >4 micron, so you need to be sure and understand why you really want to or need to use NAS 3.

Assuming SAE or something like ISO 4406 13/12/9 cleanliness then I would install a 3 micron filter to achieve this sort of standard.

Hi Kaisan

Assuming SAE or something like ISO 4406 13/12/9 cleanliness then I would install a 3 micron filter to achieve this sort of standard.

I think that to achieve NAS 1638 part 3, it would need to be at least 3 micron ABSOLUTE (not nominal) to have a chance but, I haven't looked this up in any filter documentation (that is readily available on the internet). I commonly used a 3 micron filter to attempt a cleanliness level of NAS 1638 part 6 (which is only an average level for Servo systems)!

Also, does the OP know how he/she will be able to quantify the results?

I agree with Kaisan, NAS3 is really a very stringent requirement, do you really need it? what is your application that is demanding this level of cleanliness?

What is present cleanliness level of oil? you should have very good offline filteration to achive NAS 3. upto 1 micron filters are available in the market. select the filter element depends on the present particle count.

Hi

I have considerable experience in cleanliness of hydraulic systems and it is not a straight forward process so you need to get some external advice. I do not know where you are located but Pall Filtration, Parker or MP Filtri all can provide suitable equipment and all three have literature outlining how you can select the correct filter for your application.

Regards

Oliver Dunthorne

To help with reaching the level of cleanliness you are trying to achieve we have installed a magnetic scrubber to our system prior to filter elements. The magnetic filter has trapped contaminates to sub micron levels and extended the life of our filters. Our systems are designed with 316 SS and we are amazed to see the amount captured by the magnetic scrubber.