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Particle Contamination – ISO And NAS Cleanliness Codes

Oil cleanliness is critical to the reliability of your machinery. As technology advances, the demands placed on a lubricant are ever-increasing: pressures and temperatures are higher, reservoir sizes are smaller and component tolerances are tighter.

Code ISO 4406 Number of Particles/100ml NAS 1638
>4μm >6μm >14μm
23/21/18
22/20/18
22/20/17		 8,000,000
4,000,000
4,000,000		 2,000,000
1,000,000
1,000,000		 250,000
250,000
130,000		 12
-
11		 Very Contaminated - Breakdowns Inescapable
22/20/16
21/19/16
20/18/15		 4,000,000
2,000,000
1,000,000		 1,000,000
500,000
250,000		 64,000
64,000
32,000		 -
10
9
19/17/14
18/16/13		 500,000
250,000		 130,000
64,000		 16,000
8,000		 8
7		 Minimum required cleanliness class for high pressure -
servo valve hydraulic systems, new/fresh oil DIN51524
17/15/12
16/14/12		 130,000
64,000		 32,000
16,000		 4,000
4,000		 6
-
16/14/11
15/13/10
14/12/9
13/11/8		 64,000
32,000
16,000
8,000		 6,000
8,000
4,000
2,000		 2,000
1,000
500
250		 5
4
3
2		 (ACHIEVEABLE) Results After CARDEV Microfiltration
12/10/8
12/10/7
12/10/6		 4,000
4,000
4,000		 1,000
1,000
1,000		 250
130
64		 -
1
-

100-times magnified, 1 scale mark = 10μm

NAS Class 3

NAS Class 8

NAS Class 12