Return oil color changed

Check you oil seals they may be letting in air without leaking oil.

You have not indicated the type of equipment for which the circulating oil system is employed. A lot depends on the nature of oil being used also. Synthetic or Hydrocarbon. Also the temperature at which the equipment is running. this may be due to atmospheric condition in the area surrounding the equipment.

If the running speed and temperature of the equipment is high and the hydrocarbon circulating oil may carburise and turn brownish in colour to start with, tending to go dark brown and ultimately blakish. In the case of synthetic oil it will take sometime before this can get discolourised, as it is a stable oil for wide range of operating temperatures compared to the former one.

the other thing being, some other source of discolouration may be existing without your knowledge. here you may have to go through a systematic exercise to find the cause. Rubber seal may not be compatible with the circulating oil if it is synthetic type. but this will also lead to leakage in due time from the seal/s.

the bearing cage material should also be compatible with the circulating oil in case it is synthetic oil. this do attack the cage material if not compatible.

these can be the possibilities in absence of your equipment's working conditions.

I agree with chittaranjan. Also, oils frequently contain synthetic dyes that identify the manufacturer. If the color is just changing in this way, I'd say it is from friction/heat and it's doing its job... Considering that everything is not wearing out and the temperature is in the proper range.

As oil additives "air off" the oil color will change. I bearing temp is ok why be concerned? What else is going on. Noises, increased amp draw ect?

Were I Your millwright, i'd change that bearing right off, shutdown in middle of job.. .....not worth the risk..to guess or wait. if it blows, maybe kiss 50K goodbye..thats just the parts..(question presupposes some one noticed the oil activity, like my empl. had better do..hence expensive production machine}

My est., serious, rapidly escalating small area destruction of bearing surface[s], possible cracks in race.

, but usually a precursor of ball disintergration...leading to seal failure, then air in, then oil out.Then, any time later, or before.Shaft ruined etc/injuries/etc

such as.. if this is a 36" swing Lathe Headstock main bearing...with a 2 ton shaft mounted, running 1000rpm.... being hogged... Scary...ok even worse how about a 2 t pipe 30" dia,20' long using a long[4'] boring bar..I did see one of those jump around like a landed trout..no one was killed but operator was fired..took 6mo to fix lathe...Boss very pissed.. we change bearings around here..on safe schedule..

immanent catastrophic failure of bearing:... change it! this can culminate in a few seconds sometimes...

the tiny but serious locus is enough to alter oil in contact and that very quickly, {some oils have temp warning dye, just for this type situation}... but not enough heat enough area to appreciably raise temp. Very serious symptom..if one cares about the machine, etc..

Early bearing failure most often caused by lack of cleanliness installing, and damage to cage , installing.. warped or leaking seal, instal...any of which mistake would get my empl fired.. all are encouraged to do job over, get new part or whatever..swallow pride..someone's life might depend on it.

we also warm up mach'y before hi stress jobs.. this really saves on rebuilds..

JBo

Dear Mr/Ms,

It sounds that the cause of color change is related to excess air entrance and the flow profile of your oil reservoir is not efficient any more, because of an increase production rate. At the suction side of the lubrication pump the air bubbles will increase rapidly. At the outlet of the pump, the maximum workingpressure of the system, the air bubbles will decrease in size.

A temperatur rise till 1100 Grad Celsius will locally increase the oxidation and carbonization of the oil. This phenomen is called adiabiatic compression.

Solutions are :change the flow profile of your reservoir by using baffles eg. modificate the return line of the pressure relief valve, use a vortex directly behind the pump or behind the safety relieve valve. For more details I need a drawing of the lubrication system. Email adress : cmse@planet.nl

Rene Steffens

Adittional note.. if air has been present long enough to notice, serious damage likely already exists, bearing must be changed. thats covered under proper seal instal.. [a high stress/performance/expensive loc. bearing would have monitoring, and be monitored, such as temp, etc.}

i am so thorough because i see way too many times shortcut taken which isn't really, hell to pay. Hopefully someone read this and save ...? if they should see this type cond. as described

JBo

Along with the change of color, was there a marked increase/decrease in operational fluid level in the reservoir (if equipped)?

From my experience, aeration of oils usually lighten the color of the oil as well as increase the fluid level in the reservoir (micro air bubbles). Oil darkening, coupled with a change in odor, and a decrease in fluid level, is often a sign that something is breaking down the oil, such as excess heat, or excess friction from a worn bearing.

If your operating temps are normal, and you are positive that air is being introduced into your oil supply, you could try bleeding the system of air (if it is a closed system).

Another possible cause of aeration is an over filled system. If you overfill the system, and if the coponents are designed not to operate in an oil bath, rotating components may mix air with your oil (just like using a wire whisk to beat your eggs).

It would be helpful if you could describe the change in color. Also, temperature, smell, feel, etc. More clues please.

If it ever looks like chocolate malted, then you're really hooped! Means water has entered the oil under pressure and the oil has lost all of its lubricating properties. Woof!!! Of course, if this happened, things would definitely not seem normal.