Ive got a 300 Gallon hydraulic tank (BP Bartran 32 mineral hydraulic oil), that is having alot of trouble with a black sludge forming on the 10 micron filters. Ive had it tested and its iron oxide possibly caused by a chemical reaction between the additives in the oil and the metallic moving parts, there is also a history of high temperatures. We have tried to remove the temperature (upto 80C) from the reservoir by having 2 cooling systems inline. We are after some ideas to slow the chemical reactions. Some people have said to change to a synthetic oil. Just after some ideas from outside of the square.

Cooling the oil may certainly help, but remember its just the oil in the tank. Are there local hot spots that the oil resides in for long times at high temps?

We design/build/operate railroad grinding equipment, and have low (140F) tank temps, but local hot spots in the grinding areas 200-400F at times, so oil gets up to 200 or so.

k

Stricker,

In the test you made, did you measure viscosity, AN, oxidation, water? what are the results?
Good idea to low the reservoir temperature, but I sugest, as Kevin did, measure temperatures at diferent points in the system and verify your reservoir design.

Viscosity has not changed, 60ppm of water,oxidation at 5.6abs. ISO Cleanliness 22/21/18. No Fe, Sn, Cu, Al, Pb, Cr in elemental analysis. But under microscope there is metal particals. No one is sure of the temperatures. In the next week we will be taking a full range of temperature tests. Pump has 2 outlets 60 L/min goes through a cooling system back to tank and 150 L/min keeping the pressure to the system then bleeds off ove a pressure relief. Willl keep everyone update as to what is going on.

can you elaborate more on this second circuit that bleeds off across a relief valve.
If this circuit is going across rv continuously, that could be your source of heat and oil breakdown. RV is converting mechanical energy to heat in the oil.
k

3 weeks ago we pulled doen the cooling system to find both coolers had been set-up incorrectly. What was found was the cooling water only flowed through the coolers once, the design of the cooler is for the cooling water to pass through 3 times before returning to the cooling water tank. We also replaced the oil and changed the filter to a 5 micron filter.
Since tis maintenance was completed the hotest the tank has become is 51 degree C. We have not found the full route cause but we have eliminated one of the problems.
Kevin J - the RV is the main source of the heat in the system, we are now putting a proposal together to change the arrangement so that not all of the oil goes over the RV, this may mean a new pump.
Will keep you informed
David

Striker,

It does sound as though the sludge is being caused from oxidative stresses on the oil and that you are actively pursuing the root cause of this. Filters and strainers are a favorite place for sludge to accumulate. One additional test that you may want to do is open up your used oil filter and inspect for burn holes. This will rule out the possibility of electrostatic discharge (ESD) occurring from the filters. Is the sludge collecting on the upstream or downstream side of the filters?

Greg

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Originally posted by Striker:
Ive got a 300 Gallon hydraulic tank (BP Bartran 32 mineral hydraulic oil), that is having alot of trouble with a black sludge forming on the 10 micron filters. Ive had it tested and its iron oxide possibly caused by a chemical reaction between the additives in the oil and the metallic moving parts, there is also a history of high temperatures. We have tried to remove the temperature (upto 80C) from the reservoir by having 2 cooling systems inline. We are after some ideas to slow the chemical reactions. Some people have said to change to a synthetic oil. Just after some ideas from outside of the square.

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You can consult oil company technical service staff, in this case it is BP. My understanding is that Bartan grade hydraulic oils are non zinc based alkaline inhibitors imparted oil. So, the inhibitors chemistry may be incompatible to metallic components of the system , Kumar
kumartr2@yahoo.com[/EMAIL]

Striker,

Black color of oil may be due to micro-dieseling
effect.Check for Air leaks in hydraulic system.
Use filter cart with high efficiency 5 micron
filters to improve the oil cleanliness levels.

Regards

Bala.