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We are currently using a Lithium Complex EP1 grease using an air operated grease pump in our Pellet Mill. We are regulating the filtered air at 30-35 pounds per square inch gauge. The oil seems to be separating from the grease. We are being told it could be from too much vibration.
I noticed that the grease tech data sheets don't list the oil separation specs. Any suggestions or comments would be helpful.
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Auto lube systems are a particularly specialized field for greases as they pressurize the product on a regular basis. While most suppliers simply provide an NLGI 0/1 and expect it to work in this application. A couple of areas to look for are mechanical stability which indicates it will hold up under continued working and not harden or soften. Secondly oxidation resistance is important as a lot of products oxidize quickly and harden in lines. Try to stay away from solid additives as they will collect at bends and junctions in lines. We have found that aluminium complex is the best base to manufacture greases for autolube systems.
I have observed over the years that grease separation in automated system lines can occur when the line size of the main header is sized to large. During the cycle of pressurizing and venting to operate the metering injectors, over time this action can start to squeeze out the oil from the carrying agent. This usually happen with greases of lesser quality or the occational bad batch.

If you have it happening at 30-35 psi on your pump, and assuming it is a 50:1 unit, you are only seeing approximately 1500 psi on your grease system. This usually happens at pressures over 2500 psi and at high cycle rates of say more than 4-6 cycles a minute for extended run times of hours on end. You also have the issue of trying to pump the left over thickener through the lines and metering units which just isn't going to happen at those low pressures.

If it was vibration it would also show up in the drum, in any case I would follow Bruce's suggestion and change grease.
Perhaps the amount of oil separated would not harden so much the grease for not being able to be pumped.

An NLGI 1 grease may harden to an NLGI 2 and still being pumpable. You can calculate how much grease you are pumping, and think that a 2-3% of oil can separate from a Lithium Complex grease according ASTM D 1742. In a drum, 2% is almost a gallon!!!!!
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