How to determine the lubricant type and required pressure for reciprocating compressors
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Our workshop has 18 reciprocating air compressors; although they vary in size and other aspects, their principle of operation is the same. Of these 18 compressors, some use 46# anti-wear hydraulic oil, while others use 100# ； Some require a pressure of around 0.30 Mpa, while others demand 0.45 Mpa. Could everyone please help explain what determines the lubricant type and the required pressure? Why are there so many differences?
This post was last edited by yanlianzi on 2010-12-18 at 11:27. Reply to 1# bareza: It is determined based on various structural parameters such as pressure, average piston speed, performance, and the medium being compressed. For example, air compressors require lubricants with a certain viscosity, as well as additives to prevent carbonization; high-pressure lubricants must maintain a specific viscosity, otherwise the compression efficiency will be poor. In the case of refrigeration compressors (refrigerators), small units using ammonia as a working fluid employ No. 13 refrigeration oil, while those using Freon use No. 18 and No. 25 refrigeration oil. For air compressors operating at pressures above 35 MPa, as well as petroleum gas compressors where lubricants tend to dissolve easily, synthetic lubricants such as silicone oils are generally used (they do not dissolve in gases or oils, are chemically inert, have low volatility, a high flash point, good flowability at low temperatures, and similar load-bearing capacity and friction coefficients to ordinary oils). The outlet pressure is determined according to the requirements of the process
Based on the oil consumption of your engine set, it can be determined that 46-grade oil is suitable for engines under light load, while 100-grade oil is intended for engines under medium load. However, there are regulations regarding the pressure in the lubricating oil main lines; in practice, ensuring a pressure of at least 0.25 is sufficient. It is usually controlled at 0.3! 0.4 MPa is sufficient; higher values have little effect.
After all, it was determined by the manufacturer during the initial design phase. Different lubricants have different viscosities. The same goes for oil pressure; the manufacturer provides the values. However, it is usually between 0.3MPa and 0.4MPa
It is determined based on various structural parameters such as pressure, rotational speed, the material of the bearing shells, the clearance between the bearing shells and the shaft, the average velocity of the piston, performance requirements, and the medium to be compressed. For example, air compressors require lubricants to have the appropriate viscosity at certain temperatures. 46 Good Oil is designed for lightly loaded units, while 100 is intended for units with moderate loads; in practice, a value of 0.25 or higher is sufficient. It is usually controlled at 0.3! 0.4 MPa is sufficient.
Depending on the operating conditions of the compressor, such as electronic speed, exhaust pressure, and the compressing medium, it is necessary to select an appropriate lubricant. To make this choice, one needs to consider a variety of performance parameters of the lubricant, including its viscosity, viscosity index, pour point, flash point, oxidation stability, resistance to extrusion and foaming, corrosion resistance, pH level, and material compatibility. Problems may arise if the wrong lubricant is chosen, such as abnormal shutdown of the compressor due to high oil temperature or severe shaft vibration. There are many problems such as high noise and unstable exhaust; please share the details with me, and I’ll do my best to help resolve them. QQ: 981007707