[Mechanical Equipment Technology Edition] Daily Question 201801022: Common Faults in Refrigeration Systems (8)

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This post was last edited by YORK Industrial Refrigeration on 2018-1-24 at 10:53. Starting from now, in order to enhance communication among users, a \"Question of the Day\" activity has been launched on the Mechanical Equipment Technology forum. We hope everyone will participate actively to progress and improve together! ! ! Rewards: 3 wealth points for active participation, 10-15 wealth points for correct answers. This question is valid for two days; no score will be assigned after that period. What are the reasons for the frequent need to replace refrigerant oil, as well as its rapid contamination? Possible main reasons: (1) contamination by impurities, (2) presence of moisture, (3) oxidation, (4) mixing of different types of oils, (5) mechanical wear. Considering these factors as a whole, they can be classified into external contamination and internal contamination. So-called external contamination includes the inclusion of impurities such as moisture during oil transportation, storage, and addition, as well as the mixing of different brands. Since this entire process is largely under control, problems may occur occasionally, but they generally do not happen frequently; therefore, it is unlikely that such factors cause regular contamination. Internal contamination includes things such as air infiltration due to system leaks and oil oxidation; these can cause the oil to deteriorate, generate residues and even carbon deposits, as well as lead to corrosion of metal components. This often results in frequent oil replacements and rapid contamination. The detailed analysis is as follows: 1. Contamination by impurities – Impurities that get mixed into the refrigerant oil during storage, transportation, or refilling can cause an increase in equipment pressure, an increase in current flow, overheating of the compressor (which may lead to damage), and a reduction in the heating (or cooling) capacity. 2. Moisture gets mixed in due to air entering the refrigeration system, and since the desiccant is already saturated, the moisture in the air enters the refrigeration oil. This not only causes problems such as ice blockages in the expansion valve and corrosion of metal components, but it also reduces the viscosity of the refrigeration oil. 3. Oxidation. When the compressor’s exhaust temperature is too high, it can cause the refrigeration oil to oxidize and deteriorate, resulting in residues and even carbon deposition, which undermines the lubrication in areas such as bearings. The inclusion of organic substances, mechanical impurities, etc. in the refrigeration oil can also cause the oil to age or oxidize. 4. Mixing frozen oils of different grades for use. This not only reduces the viscosity of the oil, but can even disrupt the formation of the oil film, accelerating wear on the moving parts of the compressor (especially the bearings). The situation becomes even worse if different types of refrigerant oils are used together (for example, a mixture of mineral oil and synthetic oil). 5. Mechanical wear: Once wear occurs in the compressor, it indicates that the position of the screws has shifted, and there is a significant amount of movement in both the axial and radial directions. Such movement will continue to worsen over time, and in severe cases, it can lead to the compressor seizing up. ============================== Premium promotions: Mobile equipment – Maintenance procedures for York screw compressors https://bbs.hcbbs.com/thread-1806833-1-1.html Mobile equipment – Upgrading York Quinton control centers https://bbs.hcbbs.com/thread-1804837-1-1.html Mobile equipment – Major repairs for GEA Grasso screw compressors https://bbs.hcbbs.com/thread-1800467-1-1.html Mobile equipment – Disassembly and maintenance of British HOWDEN screw compressors https://bbs.hcbbs.com/thread-1832529-1-1.html Mobile equipment – Disassembly and maintenance of Japanese MYCOM screw compressors https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=