What is the particle size of lubricating oil?

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I. The concept of granularity. Particle size refers to the concentration of solid particles of different sizes per unit volume of oil, measured in particles/100 ml, and is determined using a special particle size analyzer. Particle size is an important criterion for determining whether turbine lubricating oil is of Qualified quality. It is generally believed that when the human eye cannot see any particles in the oil, it is assumed that the oil is not contaminated. In reality, particles smaller than 40μm are invisible to the naked eye, yet particles even smaller than 40μm can have catastrophic effects on hydraulic components or bearings; often, these tiny particles play a key role in the wear process. II. Reasons for unqualified particle size in turbine lubricating oil. (1) Contaminants remaining in lubricating oil system components during manufacturing, assembly, and major overhauls. Such as: hair, iron shavings, welding slag, dust, etc. These pollutants were not removed promptly and thoroughly during the unit installation and cleaning process. (2) The main fuel tank has poor sealing performance; pollutants in the air surrounding the tank enter the tank through gaps and end up in the fuel system, contaminating the fuel quality. (3) The opening of the manual valve at the outlet of the exhaust fan in the turbine’s main oil tank is too large; tiny particles pass through the oil baffle and enter various bearing housings, thereby contaminating the lubricating oil. (4) Normal wear of various components in the lubricating oil system, as well as of hydraulic pumps, bearings, and the oil supply system, leads to contaminated oil quality. (5) The main fuel tank was refilled without conducting a mixing test first; as a result, the new fuel did not mix properly with the old fuel, leading to the formation of sludge and contamination of the fuel quality. (6) When new turbine oil arrives at the plant and is not of acceptable quality, it is added to the main oil tank, thereby contaminating the lubricating oil contained in that tank. III. What are the acceptable standards for the particle size of turbine lubricating oil? The standard for the quality of turbine oil in our country is the NAS 1638 standard set by the National Aerospace and Aviation Industries Association, requiring that the oil quality meet grade 8. Therefore, when the particle size of the lubricating oil is greater than grade 8, it is considered unqualified. IV. How to handle cases where the particle size of the turbine lubricating oil is not up to standard? 1. When the particle size of the turbine lubricating oil increases, the oil purification unit should be activated immediately to filter the oil on an ongoing basis; furthermore, samples should be taken regularly to analyze the quality of the oil, with continuous monitoring of particle size changes. 2. Immediately investigate the reasons for the unacceptable particle size; in most cases, an unacceptable particle size during operation is due to contaminated oil quality. Take targeted actions based on the identified causes to eliminate the sources of oil contamination. 3. If a leak in the cold oil cooler is suspected, switch the cold oil cooler by activating the backup unit and switching off the one that is in use ； 4. During this period, the oil filter should operate continuously 24 hours a day. In addition to the oil purification system that is in use for filtering the oil, a plate-type oil filter should also be employed to further control changes in particle size.