Comprehensive Guide to Common Lubricant Issues

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Hydraulic Oil Section 1: What are hydraulic oil and hydraulic transmission fluid? Answer: Hydraulic oil is a working medium that transmits energy or power by means of the pressure energy of the liquid within a sealed volume. Hydraulic transmission fluid is a working medium that transmits energy or power by utilizing the kinetic energy of the liquid contained within a sealed volume. 2. What are the functions of hydraulic oil and hydraulic transmission fluid? Answer: Hydraulic oil and hydraulic transmission fluid serve as a working medium for transmitting, converting, and controlling energy; at the same time, they also provide functions such as lubrication, rust prevention, cooling, and shock absorption. 3. What are the main properties that hydraulic oil should possess? Answer: Appropriate viscosity and good viscosity-temperature properties, excellent lubricating performance (anti-wear properties), good thermal and oxidative stability, hydrolytic stability, and shear stability, good anti-emulsification properties, good rust and corrosion resistance, good antifoaming and air-release properties, good suitability as a sealing material, and good cleanliness and filterability. 4. What are the product standards for mineral oil-based and synthetic hydrocarbon-based hydraulic oils in China? Which varieties are included? Answer: The product standard for mineral-based and synthetic hydrocarbon-based hydraulic oils in our country is GB11118.1－94, which specifies the technical requirements for five grades: HL, HM, HG, HV, and HS. 5. What are the main types of hydraulic oil products? What are the performance features? Answer: L-HL hydraulic oil is an antioxidant and rust-resistant hydraulic oil. L-HM hydraulic oil is an anti-wear hydraulic oil whose anti-wear properties have been improved based on HL. L-HG hydraulic oil, a hydraulic guide rail oil, is formulated by adding anti-friction agents to HM to improve its resistance to stick-slip. L-HV hydraulic oil is a low-temperature hydraulic oil whose low-temperature properties have been improved based on HM. L-HS hydraulic oil is a low-temperature hydraulic oil with a lower pour point than HV. High-pressure anti-wear hydraulic oil features enhanced anti-wear properties over the premium grade of HM hydraulic oil, and has passed high-pressure pump bench tests. Jiangsu Suzhou Kunshan Jieyouwang oil filters, oil-water separators, oil purifiers; purification, dehydration, and impurity removal for lubricants, hydraulic oils, and cutting fluids. 6. What is the difference between first-class and top-quality HM hydraulic oils? Answer: GB11118.1－94 classifies HM oils into first-class and premium grades. The first-class oils possess better wear resistance, oxidation and rust resistance, as well as emulsification resistance, while the premium grade is formulated with reference to the HF-0 standard of the American company Denison; it includes additional tests for hydrolytic stability, thermal stability, filterability, and shear stability, and it also has more stringent requirements in terms of rust resistance and wear resistance. 7. What are the differences between high-pressure anti-wear hydraulic oil and HM hydraulic oil? What criteria need to be met? Answer: The physical and chemical properties of high-pressure anti-wear hydraulic oil are exactly the same as those of premium HM hydraulic oil. On this basis, bench tests have been conducted using Denison high-pressure vane pumps (T5D, 17.5 MPa) and high-pressure piston pumps (P46, 35 MPa); these properties meet the Denison HF-0 specifications in the United States. In China, the standards for such oils are currently set by enterprises, reflecting the highest level of quality for hydraulic oils at present. 8. What are the **representative specifications for anti-wear hydraulic oils in Europe and the United States? Answer: The main international specifications for hydraulic oil are: German DIN51524(II) and DIN51524(III) standards. HF-0 specification from Denison Company in the United States. Cincinnati-Milacron Company, USA, P-68/P-69/P-70 specifications. Vickers Company, USA, M-2950-S/Ⅰ－286－S specifications. 9. What are the main types of anti-wear hydraulic oils? What are its characteristics? Answer: Anti-wear hydraulic oils are mainly classified into zinc-based anti-wear hydraulic oils (gray-type) and ashless anti-wear hydraulic oils, based on the composition of their anti-wear additives. The anti-wear agent contained in zinc-based anti-wear hydraulic oils is primarily zinc dialkyldithiophosphate, while ashless anti-wear hydraulic oils use S- and P-type anti-wear agents. 10. What are the viscosity grades for hydraulic oil? How many are commonly used? Answer: In our country, the viscosity grades of hydraulic oil are divided into eight categories: 10, 15, 22, 32, 46, 68, 100, and 150. The most commonly used viscosity grades are 32, 46, and 68. High-precision oil filters, coalescing separation, edible oils, coal mill oil, turbine oil, vacuum oil filters, centrifugal oil filters, high-precision oil filters, electrostatic oil filters, oil purifiers, filters, filter elements. 11. What are the various types of specialized hydraulic oils available in China currently? Answer: To meet the needs of special hydraulic machinery and specific applications, China continues to produce certain specialized hydraulic oils that fall outside the standard classification categories. These include aviation hydraulic oil, marine hydraulic oil, silver-resistant hydraulic oil, clean hydraulic oil, CNC hydraulic oil, coal mining oil, and artillery hydraulic oil. The quality and performance of these oils are mostly in the HL-HM range or close to HV. 12. What are the similarities and differences in the performance characteristics of HV and HS hydraulic oils? Answer: Both HV and HS hydraulic oils are referred to as low-temperature anti-wear hydraulic oils; they are hydraulic oils whose low-temperature performance has been improved upon that of HM, and they possess excellent low-temperature performance as well as good viscosity-temperature characteristics. HV oil has a viscosity index of over 130, and its pour point is lower than that of HM oil, making it suitable for cold regions ； HS oil has better viscosity-temperature properties and low-temperature performance compared to HV oil; it has a higher viscosity index and a lower pour point, making it suitable for extremely cold regions. 13. What are the principles for selecting hydraulic oil? Answer: (1) Generally, for indoor fixed equipment, when the hydraulic system pressure is 14.0 MPa, HM or high-pressure anti-wear hydraulic oil should be used. (2) Use HV or HS oil for outdoor cold areas or extremely cold areas. (3) For equipment near high-temperature heat sources, use flame-resistant hydraulic oil. (4) For equipment with high environmental requirements (such as food machinery), choose hydraulic oil that is environmentally acceptable. (5) For hydraulic equipment that requires a long service life and operates in harsh environmental conditions, it is necessary to use top-quality hydraulic oil ； For hydraulic equipment that requires a short service life and mild operating conditions, first-class hydraulic oil should be selected. (6) A single system is shared for hydraulic and guide rail lubrication; hydraulic guide rail oil should be used. (7) For open-loop CNC machines equipped with electro-hydraulic pulse motors, CNC machine hydraulic oil is used, while for closed-loop systems using electro-hydraulic servos, clean hydraulic oil is used. (8) For hydraulic systems with silver-containing components, use silver-resistant hydraulic oil. 14. What should be noted when using hydraulic oil? Answer: Prevent the hydraulic system from being contaminated, prevent water from entering, prevent air from entering, and control the operating temperature of the hydraulic oil. 15. What parameters should be monitored for hydraulic oil during use? What are the criteria for changing hydraulic oil? Answer: When using hydraulic oil, key parameters to monitor include the oil’s appearance, viscosity changes, color changes, acid value changes, moisture content, impurities, pentane-insoluble substances, and corrosion. Regular testing of these parameters allows for early detection of problems, enabling appropriate actions to prevent failures. China has established replacement criteria for HL and HM oils, specified in SH/T 0476–92 and SH/T 0599–94 respectively. In principle, hydraulic oil in use should be replaced with fresh oil once any of these parameters reach the specified replacement levels. Treatment of contaminated and emulsified lubricating oil waste – oil filters, filtration systems, demulsification filtration, and other filtration equipment. For more information on lubricants, please visit the website of Jieyouwang Oil Filter; you can find it by searching for “Jieyouwang” on Baidu. The site provides a wealth of information on the use, maintenance, and recycling of hydraulic oil. In general, this approach allows hydraulic oil to be used for over five years, keeping it in a condition similar to that of new oil. There are also videos on hydraulic oil filtration on the site, which represent valuable resources for maintaining hydraulic equipment and extending the lifespan of hydraulic oil. Useful reference!