Water Contamination in Lubricating Oil

Water source: coolant leakage, seal failure, moisture condensation in the air, external water entering through the breathing cap seal system.

Form of existence: dissolved water, emulsified water, free water.

Dissolved water: Water existing between the oil molecules, the size of which is generally below 0.1 um.

Emulsified water: water highly dispersed in the oil, the size is generally less than 10UM.

Free water: Water that settles in the lower part of the oil fluid, generally under 100UM in size.

Free water -- In mineral oils, it usually settles at the bottom, and in synthetic fluids such as phosphates or chlorinated hydrocarbons, it floats at the top.

Emulsified water -- after water is mixed into lubricating oil, it will have affinity with water and make the oil emulsified into emulsion. The stability of the emulsion depends on the nature and state of the liquid. Generally, the greater the viscosity of lubricating oil is, the more stable the emulsion with water is.

When the oil temperature rises and the pressure rises, the emulsified water and free water will dissolve in the oil, and the dissolved water content will increase.

The harm of water to oil: make the oil viscosity decrease, destroy the oil film, cause serious mechanical wear, produce acid substance, increase the acid value of oil, increase the corrosion of the system, seriously weaken the oil performance, reduce the service life.

Influence of moisture on oil products:

1: emulsified oil (make the friction parts of the machine, hydraulic components internal rust, reduce lubrication performance, so that the wear of parts aggravate the efficiency of the system).

2: the generation of foam (blocking the oil passage, improve the lubricating oil solidification point, weaken the strength of the oil film, reduce the lubrication function, resulting in parts wear). 

3: hydrolytic additives (water will act with some additives in the oil, hydrolysis reaction, precipitation and gum and other pollutants, accelerate the oxidation of oil).

4: embroidery corrosion (more than 300PPM of water in the lubrication system may cause carbon steel or alloy steel rust).

5: promote sludge generation (water and wear metal particles and iron oxide action to produce iron soap, iron soap and lubricating oil in the dust, machine slag and gum and other pollutants mixed into sludge).

6: cause ice particles (in the northern winter, the lubricating oil contains water, easy to condense into tiny ice particles, easy to block the clearance and outlet of the control element in the lubrication system).

7: reduce insulation - (such as transformer oil, invasion of water or impurities, insulation performance deteriorated sharply).