Dear All,

First of all I would ike to know what is the difference between :

1) Transmission fluid (as used in a clutch, gearbox, etc)

and

2) Lube oil (as in the roller/journal bearing lube oils)

My question is as follows:

In our plant we have an air blower driven by a combination of Steam turbine and Electric motor and the transmission is thru a Clutch. This means, when we want the steam turbine to operate then the electric motor can be stopped and vice versa. The blower is in the centre and on one side we have electric motor and on the other side the steam turbine; either side we have a clutch to transmit the power, as desired.

We are using Shell Automatic Transmission fluid IID for the clutch. On the clutch to the turbine side, we recently saw a change in color of the transmission fluid. In order to explain the color, i visited the website (http://gotomy.com/color.html) where the color codes (in terms of hexadecimal RBG values ) are given.
Based on this color chart, the colors are:
a) THe base color of this oil is a syrupy red (RBG:660033)

b) The color of the current oil is a milky pink(RBG: FFCCFF and FF99FF)

I would like to know what may have caused the color change. What tests can we do to ascertain those causes etc. If you are recommending any tests then I would appreciate if the applicable ASTM test nos are provided.

Also, if possible, please let me know what things can be done to prevent this type of color change in future.

For your information, the clutch on the motor side is still retaining its original color. Normally the electric motor is not running.

I will update this post when i have data on the last lube oil change, history of such color change occurence, etc for members' clearer judgement.

Thanks

Well, the knee-jerk reaction is water contamination, possibly from condensation, or aeration (overfill/underfill, mechanical problem of sometype). Pull a sample and allow to sit for a couple of days and see if the fluid changes back in color. (possibly method of checking for aeration).

Thanks Abus. That eventually seemed to be the cause. I didnt pull out a sample, but it was found that some steam ingress from the lube oil vent line could be a reason and corrective actions were taken.

ANy idea on how to quickly assess the water content in the lube oil, other than the "settlement" test that you proposed.

Hot plate will tell you if water is there. Similar to throwing fish in hot oil. If there is any water it will bubble and make crackling noise when put on a hot plate. Be careful, don't burn yourself.

Sorry that I forgot about this thread...

Well, the settlement test is more for trapped air than water, oil may or may not settle out of lube oils depending on a number of factors.

OilKan's hot plate test is good, though, I prefer to precisely measure a sample of the oil (by wieght works well) then heat it for, say an hour at 95C or so on a hotplate. A decrease in volume pretty much implies water.

Now often having a hotplate in the field, I do the same with a lighter and the bottom 2 inches of a beer can. Fast and simple. If there is water, there is a problem, so I don't often care how much.