You may think that new hydraulic oil is automatically clean, but that’s not really the case. New hydraulic oil straight from the drum has a typical cleanliness level of ISO 4406 23/21/18.
Now that number may not mean a lot to you, but it’s four cleanliness code levels below that considered
ideal for a high pressure, high performance hydraulic system.
Looking at it another way, a 25 GPM pump operating continuously in hydraulic oil at 23/21/18 will
circulate 3,500 pounds of dirt to the hydraulic system’s components each year.
To add hydraulic oil, and not the dirt, always filter new oil prior to use in a hydraulic system.
This can be accomplished by pumping the oil into the hydraulic reservoir through the system’s return filter. The easiest way to do this is to install a tee in the return line and attach a quick-connector to the
branch of this tee.
Attach the other half of the quick-connector to the discharge hose of a drum pump.
When hydraulic oil needs to be added to the reservoir, the drum pump is coupled to the return line and the oil is pumped into the reservoir through the return filter.
As well as filtering the oil, spills are avoided and the ingress of external contamination is prevented.