States of Coexistence Next to particlates contamination,moisture is the second-most-destructive contaminant found in machinery.
Water can exist in oil in the following three states:
Dissolved Contrary to what I was taught, oil and water do blend. The amount of water dissolving into the oil depends upon the oil’s base stock, condition, additives, contaminants amount and temperature. Typically, oxidized, lower grade oil that is heavily additized can hold as much as 2,000 ppm moisture in the dissolved state. In this state, water is not visible in the oil. Conversely, new, high-grade oils with minimal additives will hold little dissolved water.
Emulsified Once the volume of moisture has passed the maximum level for it to stay dissolved, the oil becomes saturated. At this point, the water is suspended in the oil in very tinydroplets known as an emulsion. Emulsified water is often referred because it has a misty appearance.
Free Adding more water to an emulsified oil/water mixture will lead to a separation of the two phases, producing a layer of free water. This water separates from the oil due to inherent insolubility and the specific gravity difference between the two fluids. In most cases, free water is found at the bottom of tanks and sumps.