Caterpillar recommends maintaining cleanliness ratings for various fluids in order to get maximum life from the components they lubricate. Operating cleanliness of ISO 18/15 tolerates only 2,500 particles of contaminant 6 microns and larger per milliliter of hydraulic fluid, and no more than 320 particles 14 microns and larger. You get there by starting maintenance with a regular hydraulic-oil sampling program to monitor contaminant levels and respond as necessary to control run-away conditions.
Each ISO number increase represents a doubling of the amount of contaminant in the oil.
Take the example of a hydraulic system with a 32-gallon-per-minute pump. In 200 days, working eight hours per day, that pump will pass 79 pounds of dirt if the oil has a consistent ISO 18/15 cleanliness rating. If the ISO rating jumps to 21/18, the pump moves 630 pounds of dirt.
Use a kidney-loop or off-machine filtration cart to clean oil and reservoirs regularly.
Also, observe good shop keeping:
- keep floors clean
- clean up spills using absorbent mats (granular oil dry and kitty litter create a lot of dust)
- protect packaged parts and oil from contamination before they are installed
- prevent contamination of hoses while in storage by capping their ends
- use dedicated, clean containers to transport oil to a machine.
Install highly efficient, desiccant breather filters on reservoirs and bulk storage tanks to remove particles and moisture.
Filter fill oil coming out of storage tanks and while pumping it into machine reservoirs, if possible.
|Fluid Contamination ISO Targets|
|Operating cleanliness of ISO 18/15 tolerates only 2,500 particles of contaminant 6 microns and larger per milliliter of hydraulic fluid, and no more than 320 particles 14 microns and larger.|
|Fill Oil||ISO 16/13|
|Fuel (recommended)||ISO 18/16/13|
|Hydraulic Systems||ISO 18/15|
|Transmissions (electrically controlled)||ISO 18/15|
|Transmissions (mechanically controlled)||ISO 21/17|
|Filtered Differentials & Wheel Groups||ISO 18/15|
|New & Rebuilt Engine||ISO 18/15|
|Component Rebuilds||ISO 16/13|