Particle Contamination-
National Aerospace Standards (NAS) , SAE Grade, two versions of one ISO
Standard. A lot of different methods for lube oil cleanliness evaluation
and a lot of confused engineers. Sounds like a job for VibroNurse!!!
The following tables gives some rough guidelines of
common practice for setting targets of cleanliness levels in different systems.
These guidelines are minimum fluid cleanliness
levels required for an acceptable lifetime of equipment and components.
| Equipment | ISO 4406 | NAS 1638 |
| Robotics | 14/12/9 | 4 |
| Ball Bearings | 14/12/9 | 4 |
| Turbine Oils | 14/12/9 | 4 |
| Small and Medium Gearboxes | 14/12/9 | 4 |
| Roller Bearings | 16/14/11 | 5 |
| Hydraulic Servo Systems | 16/14/11 | 5 |
| Transmission Gearboxes | 16/14/11 | 5 |
| Journal Bearings | 17/15/12 | 6 |
| Mobile Equipment | 18/16/13 | 7 |
| Hydraulic Motors and Pumps | 18/16/13 | 7 |
| Diesel Engines | 19/17/14 | 8 |