What are the causes of air bubbles in lubricating oil?
There are mainly three kinds of air mixed in lubricating oil: air dissolved in oil (invisible to the naked eye), suspended, trapped in oil, bubbles that cannot be released inside, and foam on the oil surface. Among them, the most harmful to the machine and lubricating oil is the air bubble suspended in the oil.
Foam will gather and float on the oil surface, and the volume is relatively large. If there is a bubble, it is usually necessary to guard against the formation of bubbles inside the oil. Bubbles are suspended in the oil, which are small in volume, but do great harm. Bubbles will cause the oil to be turbid. If the oil is turbid, take some oil samples. If stratification occurs, the turbid oil is caused by water or other liquid pollution. If the oil sample is clear after a period of time, bubbles are mixed in the oil.
Causes of air bubbles in lubricating oil:
1. many reasons can cause bubbles and bubbles to increase in lubricating oil. The most common one is water in lubricating oil. When the oil is mixed with water, the surface tension of the oil will be reduced. Instead of forming a large bubble to float to the liquid surface, it will break into small bubbles and float in the oil.
2. The lubricating oil is polluted: the oil is mixed with other liquids, cleaners, solvents and other substances.
3. oxidation of lubricating oil: the oxidation of oil causes the antifoaming property of the oil to decrease. Some oil will increase after the use of the oil for a long time. The most common reason is the oxidation of oil.
4. Additive depletion: the loss of antifoaming agent will also cause the increase of bubbles. It should be noted that more antifoaming agent will also cause bubbles. Some users see bubbles increase or anti foaming agents are consumed, will add anti foaming agent, more anti foaming agent will also cause bubble problem.
5. Leakage: air leaks from oil pipes, seals and other parts.
6. Poor design of oil tank: the oil tank is too small, there is no filter screen and baffle for filtering bubbles, the distance between oil return pipe and oil suction pipe is too close, and the oil flow rate is too fast to release bubbles.
7. The viscosity of lubricating oil is not properly selected.
There are bubbles and bubbles in lubricating oil.
Bubbles and foam are harmful to lubricating oil and machinery. Bubbles will accelerate the oxidation deterioration rate of lubricating oil, accelerate consumption of additives, affect heat dissipation, and can not form a complete lubricant film, causing wear and tear to equipment. Bubbles in the high-pressure system will also cause local high temperature, so that the oil quickly deterioration.
Hazards to equipment:
Air is easy to compress, there is gas in the lubricating oil, the thickness of the oil film will become thinner or even the oil film will break, and the mechanical parts will be directly rubbed, resulting in wear.
Cause cavitation: the bubble is broken under pressure, forming cavitation damage to the metal surface.
Affect mechanical operation: air bubbles will affect the stable operation of mechanical system, such as unstable operation, out of control action, jam of paint film on valve core, corrosion and other problems of hydraulic system.
How to prevent air bubbles in lubricating oil?
What should we do when the foam in the tank increases?
1. Use a clean and dry sampling bottle to take some oil samples from the oil discharge port, and observe whether there is water in the flowing oil - free water or the oil is turbid, stratified, emulsified and white. If there is water, the foam may be caused by water in the lubricating oil.
2. If it is not caused by moisture, check the air leakage point and oil level. If everything is normal, oil sampling shall be carried out for oil detection to check whether it is polluted by other chemicals or oil, or additives consumption and oil deterioration.
3. If the oil tank is poorly designed, it can be considered to increase the volume of the oil tank, and install baffles and strainers in the oil return area and oil suction area.