How to Maintain the Lubrication System of the Chiller?

How to Maintain the Lubrication System of the Chiller?

In the chiller operation system, more attention is paid to the three parts of the chiller’s refrigerant circulation system, chilled water circulation system and electrical control system, while the lubrication system is often overlooked. As everyone knows, this system is also very important for industrial chillers.

The failure of the lubrication part of the chiller is not a problem of the lubrication system itself, but it will eventually lead to the failure of the system. For example, the selection of the structure of the piston ring at the cylinder, improper processing and assembly can cause a large amount of oil leakage, and abnormal leakage at the shaft seal will significantly reduce the oil level in the crankcase, which will lead to the phenomenon of cavitation in the oil pump. Another example is that the assembly gap between the big and small head bearing bushes of the connecting rod and the front and rear main bearings is too small, the lubricating oil is too dirty, and the lubricating oil has deteriorated after long-term use, etc., will increase the friction and wear of moving parts, or at the same time, high and low pressure gas blowing will occur due to severe wear of the cylinder. All will cause the crankcase to heat up, the oil temperature will rise, and the viscosity of the lubricating oil will decrease, thereby forming a vicious cycle of lubrication conditions and causing the failure of the lubrication system. Therefore, the failure analysis of the lubrication system should be comprehensive, that is, in addition to the problems of the lubrication system itself, it should also be checked, analyzed and judged from the operating conditions of the industrial chiller, such as whether there is abnormal vibration, sound, heat and leakage, etc.

The most common failures of the lubrication system of the chiller are: no pressure of the oil pump, failure of pressure regulation and violent swing of the pointer of the pressure gauge. The main reasons are:

1. The system is seriously leaking.

2. The oil pump works for a long time, the wear of the pump is serious, the internal leakage is too large, and the volumetric effect is obviously reduced.

3. The oil temperature in the crankcase is too low, the viscosity of the refrigerating lubricating oil is too high, the filter screen of the pump inlet oil filter is too dense, the filter element is blocked, and the oil level is too low, the oil pump is difficult to absorb oil, resulting in air suction.

4. The pressure regulating valve core is stuck in the open position or the spring of the pressure regulating valve fails.

From the following aspects, it can be determined whether the lubrication system of the chiller is normal:

1. The oil level in the crankcase should be sufficient and stable for a long time.

2. The oil temperature in the crankcase should be kept between 10-65°C, and the most suitable working temperature is 35-55°C.

3. The filter element of the oil filter should not be blocked, and the fine oil filter with differential pressure signal should have a blockage signal.

4. The specified oil pressure gauge is stable, and the indicated pressure should be 0.05-0.3MPa higher than the suction pressure for the piston or chiller, and 0.2-0.3MPa higher than the condensing pressure for the screw refrigerator.

In the maintenance of the lubrication system of the chiller, the following points should be paid attention to:

1. Pay attention to observe whether the oil level, oil temperature and oil pressure are normal during daily inspection.

2. Regularly check the oil quality according to the oil change index specified by the refrigeration lubricating oil, and replace or supplement the filtered new oil.

3. Pay attention to check and adjust the end face clearance of the oil pump during maintenance, and replace the pump if necessary. The end face clearance of the pump is about 0.03-0.08mm depending on the size and specification. For specific values, please refer to the assembly technical requirements and factory regulations of the pump.

4. Regularly replace or clean the filter element, pipeline and crankcase.

The maintenance technical requirements of the lubrication system of the chiller are relatively strong, mainly related to the performance of the main compressor. It is recommended that professionals perform the maintenance to avoid unnecessary losses.

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