We use magnetic face seals in place of lip seals on a wide variety of applications, usually on pumps but also gearboxes and other equipment. The only factor limiting the speed of operation is the heat generated and this cokes (carbonises)the oil.
I am looking for information on what the coking temperatures would be for a range of proprietry oils. The oil companies do not seems to give this information on their data sheets and a brief trawl of the internet failed to get anything meaningful.
Does anyone have any pointers they could give me so I can find the coking temperatures, or am being too simplistic and getting into a very complicated area?

Hi Peter,
You can most likely figure the "limits " for each oil your self by exposing the samples to the same heat source and observe how long it takes to heat damage each individual sample.
We monitor plants with simular seals and do not find this difficulty so........
Do you think the carbonisation you see is because of frictional heat in the seal or is it from ambient temperature causing the difficulty??

Rob S

I think it is a combintation of the temperature generated by the bearing, gearbox etc and the temperature generated by the running of the seal. It is easy to test the temperature generated by the seal alone and from this we have been able to determine that most lubricating oils coke at about 120-150 C , however I cannot find this figure written down anywhere and obviously it varies from oil to oil. What I would ideally like to do is compile a chart of various grades and types of oils with their coking temperatures so we can ascertain if a seal is suitable for certain application.

I UNDERSTAND FOR SUMP LUBRICATION (NOT FORCED CIRCULATION) OIL BATH TEMPERATURE SHOULD NOT EXCEED 82 DEG C.

SEAL PART CAN POSSIBLY OPEARTE UPTO 120 DEG C, BUT OIL DEGRADATION WILL DEFINITELY OCCUR.

IF THESE SEALS ARE USED IN APPLICATION WITH FORCED LUBRICATION THAN 120 DEG C SHOULD NOT BE A PROBLEM.

Are you trying to determine the MEOT?