The Hydraulic Oil change colour in short time

It is very similar to oil oxidation. May be your hydraulic system has begin to work at higher temperature. Do you measure viscosity and TAN? Other reason - contaminant. What cleanness this oil?

Hungtv,

How long the service hours of the black oil?

Regards,

Nurudin

Hi All,
Thanks for your reply. The maximum Temperature is about 60 degree. TAN=0.25, KV at 40 degree = 46.2 cSt, n-heptane Insolubles = 0.028 %Wt. NAS 10. I think that NAS 10 is too high and It means the Oil has contamination.
But I have the other sample of Batran HV 46 hasn't changed the colour but has NAS 11?
The Oil Service is about 1800 hour.
I dont still understand why?
Thanks and regards

Hungtv,
Do you have the analytical data other sample of Bartran HV 46, that has not change colour? May be you made TAN of fresh Bartran?
In reference to contamination I has the experience with colour of hydraulic oil from press on tobacco plant. There was oil with bright red colouк instead stramineous as it must be for usual hydraulic oil. It was tabacco dust that ingressed in reservoir through canted can instead cap.

Hungtv,

as per my consideration, your oil is still OK
If you said it was black, what is the ASTM color code of this oil (1 - 8)?

Check again the details of NAS
Do you get the details of particles count from 5 - 100 u?
NAS / ISO Cleanliness Code which tested by laser particle count is very sensitive. And frequent creating error result.

for example, I will not believe the result of ISO Cleanliness if the result is showing 16/16 or 17/17.

Regards,

Nurudin

TAN of hydraulic oil new should be always less than 1.
Our DNR Corp HYD oil68 has TAN of 0.00022 means if it gets mixed with metal working fluid than also it will not contaminate MWF.Hence life of MWF will increase drastically. In case of injection machines this oil will outperform because to reach tan of more than 1 it will take around 10000 hrs.

DNR Corp
91 22 9820229229.

Hi Hungtv

Nas 10 is approx an ISO 19/16 or 5000 particles per mL > 5 µm, You should be better than ISO 16/13 or 600 particles per mL > 5 µm,,
Is there difference in the smell of the two oils, is the dark fluid heat damaged and if so it should smell more acrid than the new oil, This could indicate hard particle damage, check the main oil filter media for visible metal, check for dirt entry, hope this helps, regards
Rob S