Number of views: 3 Author: AERTERANS Published on: 2024-09-07 Source: AERTERANS
1. Compressor maintenance case analysis
Recently, a customer in the factory sent a screw compressor for repair. The customer reported that the machine had a low oil pressure shutdown, and the equipment was subsequently stuck. After disassembly inspection by the maintenance department, it was found that the radial and axial bearings of the exhaust end of the male rotor were damaged due to oil deficiency, and the oil holes of the oil injection plate were also blocked. It was analyzed that the direct cause of bearing damage was that the customer did not replace the old oil filter in time during use, causing the residual impurities inside the oil filter to enter the oil circuit system as the equipment operates. Since the injection plate is located at the end of the oil circuit system and the diameter of the injection hole is small, these impurities can easily clog the injection hole, causing a series of failures.
Problem analysis:
After the equipment disintegration, the technical department analyzed the oil filtration problem.
1. Regarding the filtration accuracy of oil filtration. From the user's perspective, we learned that the oil filtration filtration accuracy purchased by the user is 25μm, which is far exceeding the original design requirements of the equipment 7-8μm (maximum 10μm). Due to the low filtration accuracy, impurities can enter the oil circuit system, thereby blocking the oil holes of the oil injection pan, eventually causing oil deficiency damage to the bearings at the exhaust end of the male rotor and equipment to get stuck.
Design requirements:
(1) The filter must be changed every time the oil is changed
(2) The filter accuracy level is 10μm
(3) Under clean conditions, the pressure loss is 0.2bar, and the maximum pressure loss cannot exceed 2bar
(4) When the oil pressure is 1.8 bar, the machine stops the machine, and when the inverter is driven, the oil pressure is 0.5 bar, and the oil pressure switch is transferred to another protective hydraulic switch set to 0.5 bar to stop the machine.
(5) Use belt disassembly device to disassemble when disassembly
(6) Apply some grease on the sealing ring before installing the new filter, and then screw it on
2. Filter material. The user originally used ordinary fiberglass paper, but this material may be at risk of damage during later use. To improve this problem, the design puts forward new requirements: the use of a material combination of high-precision fiberglass paper combined with metal mesh. High-precision fiberglass paper can ensure the accuracy of filtration, while the function of the metal mesh is to prevent the fiber paper structure from being damaged, thereby improving the durability and stability of the overall material.
Customer independent procurement:
Design requirements:
3. Overflow valve. The user purchased an oil filter with an overflow valve. The pressure setting of the oil filter is small, resulting in a bypass operation at a lower pressure. The opening of the relief valve increases the risk of impurities entering the oil circuit system, which may adversely affect the stability and safety of the equipment. Therefore, the design selection requires that the oil filter does not have an overflow valve to avoid potential risks.
2. Analyze the use of overflow bypass valve in oil filtration through product testing
According to the above operating conditions, will the overflow valve be opened or is there a risk when the equipment is just opened?
1. If the filter element is clean + the lubricant meets the requirements + the filter element resistance is less than 2.5bar, the overflow valve is not opened → there is no risk in the equipment operation;
