ISO and NAS Cleanliness Codes

Internationally recognized standards are used to quantify the number and size of particles in oil. This chart illustrates both standards, the condition of a typical system, and oil cleanliness levels obtained using Oil Recycling Technologies.

ISO	Particles/ml 4406:1999			NAS
	>4 MIC	>6 MIC	>14 MIC	1638(1964)
A 23/21/18	80000	20000	2500	12
22/20/18	40000	10000	2500	–
22/20/17	40000	10000	1300	11
22/20/16	40000	10000	640	–
21/19/16	20000	5000	640	10
20/18/15	10000	2500	320	9
B 19/17/14	5000	1300	160	8
19/16/13	5000	640	80	7
18/15/12	2500	320	40	6
17/14/12	1300	160	40	–
17/14/11	1300	160	20	5
16/14/11	640	160	20	5
C 15/13/10	320	80	10	4
14/12/09	160	40	5	3

Oil operating in this category will shorten the life of hydraulic components & oil, causing premature wear and continuous breakdowns.

Oil operating in this category will extend oil & component life, reducing hydraulic system breakdowns.

Fluid Cleanliness Levels

Hydraulic system manufacturers set ISO cleanliness levels to extend component life. Exceeding these cleanliness targets leads to increased wear, reduced performance, and higher failure rates.

Component	ISO	NAS
Servo control valves	16/14/11	5
Proportional valves	17/14/12	6
Vane and piston pumps/motors	19/16/13	7
Vane and piston pumps/motors	19/16/13	7
Directional and pressure control valves	19/16/13	7
Gear pumps/motors	19/17/14	8
Flow control valves cylinders	20/18/15	9
New unused oil	19/17/14	8