Compressor repair case background

Recently, a customer sent a compressor to start the machine on site and then shut down after fifty minutes, and it needs repair. After disassembly and inspection by our factory's maintenance department, it was found that the thrust bearings on the two rotors at the exhaust end were damaged and the ball was deformed. Judging from the damage to the bearing, it was caused by oil-deficient dry friction, and other bearings also had oil films. It is suspected that lubricating oil has not been injected into each lubricating point. Therefore, the damage to the bearing due to oil-free operation is the fundamental reason for the fault.

Analysis of the cause of failure

After the equipment disintegration, the technical department analyzed the use of oil filtration

1. Regarding the installation method of oil in and out on site.

When disassembling the machine head, it was found that the installation method of the oil filter seat at the oil cooler was reversed from that during the workshop test (the oil pressure joint was facing down during the test machine, and the oil pressure joint was facing up during the on-site operation), and the oil pressure joint was facing upward. The monitoring oil pressure point was the system oil pressure before the oil filter, and there were hidden dangers in the installation method of oil in and out on-site;

On-site installation method: 2# is oil inlet, 1# is oil outlet, and the oil inlet and oil pressure monitoring point are the same system

Normal installation method: 1# is oil inlet, 2# is oil outlet, and the oil outlet and oil pressure monitoring points are the same system pipeline

2. About check valve.

Normally, oil is fed to the small holes around the surroundings, and oil is fed from the main hole in the middle after filtering through the filter element. On-site shutdown inspection found that the inlet and outlet oil pipes were inverted, which was the main hole. Due to the existence of the check valve, the small holes around could not produce oil, so a normal circulation circuit could not be formed, which eventually led to the failure of the system to lubricate normally and oil loss. Therefore, in order to avoid the system from being unable to lubricate normally due to errors in the inlet and outlet oil pipe installation, the measures that can be taken are: First, mark the installation ports of the inlet and outlet oil pipes to prevent installation errors; Second, select oil filters without a check valve, so that even if the inlet and outlet oil pipes are installed incorrectly, the system can be lubricated normally.

So, what exactly does oil filtration have and what is its structure?

The structure of the oil filter generally includes parts such as the filter element, the shell, and the seal. When the compressor is running, the lubricating oil is sucked into the housing of the oil filter and then filtered through the filter element. As the core component of oil filtration, the filter element is mainly used to block solid particles, metal chips, silt and other impurities in the oil and ensure the purity of the oil. The materials for the manufacture of filter elements include fiber materials, metal mesh, ceramics, etc., which have different filtration accuracy and filtration efficiency. To ensure that the oil filtration continues to work effectively, regular replacement is very necessary.

Finally, let’s talk about the recommended replacement cycle of oil filtration

It is usually recommended to replace the lubricant every 4000 hours according to the working conditions. The oil filter must be replaced or cleaned every time the lubricant is replaced. In addition, a belt wrench or similar tool is required for disassembly.

When installing a new oil filter, lubricate the sealing ring with a small amount of lubricating oil and tighten the filter screws by hand. Do not change the oil filter when the lubricant is very hot! Danger of scalds!