Causes of abnormal noises in piston compressors

　Piston compressors have components that are subject to alternating loads, as well as many components that slide under high pressure. Moreover, gases generate compression heat, mechanical vibrations, and gas pressure fluctuations; therefore, for compressors to operate efficiently, safe operation and proper maintenance are essential. Since compressors often experience various faults during operation, and the reasons for these faults are complex, it is necessary to conduct careful observation and research, carry out numerous tests, and rely on extensive practical experience in order to determine the true cause of the fault. 　　The main abnormal phenomena that occur during compressor operation are as follows: 1. Abnormal vibration of the compressor ； 　　2、Abnormal compressor noise ； 　　3. Abnormal overheating of the compressor ； 　　4. Abnormal suction and discharge pressures of the compressor ； 　　5. The compressor’s exhaust volume does not meet the design requirements ； 　　6. Abnormal oil supply in the compressor oil circuit ； 　　7. Abnormal water supply in the compressor’s water circuit ； 　　8. The service life of the compressor’s vulnerable components is short ； 　　9. Breakage and fracture of the compressor ； 　　10. Fire and explosion in the compressor ； 　　11. Faults indicated on the gauge chart. 　　The table below lists some of the abnormal phenomena that occur during compressor operation, along with their causes and general solutions. Some causes of abnormal phenomena in compressors and solutions (I): Causes of abnormal phenomena and solutions. Abnormal vibration in the compressor cylinders: 1. During installation, the gaps between the cylinder supports and the base were not properly adjusted, resulting in inadequate support. Recheck the gaps around the cylinder supports as well as the tension on the bolts to ensure proper support. 2. The piping connecting the various water and air pipes in the compressor was not installed correctly; this led to looseness or excessive stress, causing the pipes to vibrate and thus inducing vibration in the compressor cylinders. Thoroughly inspect the fitting and connection of all pipes in the compressor to eliminate such vibrations. 3. If the clearance within the compressor cylinders is too small, the piston may collide with the inner walls of the cylinders at the top and bottom dead centers, resulting in severe impacts and vibrations. The compressor should be inspected, and an appropriate amount of clearance should be maintained as specified. 4. If the tightening nuts on the compressor piston are loose, this can cause knocking and vibration. The compressor should be stopped immediately for inspection, and the nuts should be tightened securely to prevent further problems. 5. During the installation or maintenance of the compressor, if things fall into the cylinder due to improper operation and are not properly removed, this can result in knocking sounds and vibrations. It is necessary to disassemble the compressor’s cylinder to conduct a thorough inspection and cleaning in order to remove any foreign objects. 6. Vibration in the cylinder may occur due to improper balancing of the compressor’s crankshaft or poor dynamic balance of the flywheel. In such cases, it is necessary to replace the balance weights and adjust the dynamic balance of the flywheel. Abnormal noises from the motor: 1. Abnormal noises caused by overload on the compressor. 2. Abnormal noises resulting from contact between the rotating parts of the compressor. It is necessary to check the compressor’s load level and carry out maintenance as needed. Abnormal exhaust volume caused by faults in the piston rings: 1. Poor quality lubricant or insufficient amount of lubricant can lead to high temperatures inside the cylinder, causing the piston rings to stick together, which reduces the exhaust volume and may also cause pressure to be redistributed across various stages. The piston should be removed to inspect the piston rings, and the grooves on the piston should be cleaned. Piston rings that pass the inspection can be reused, while those that are severely damaged need to be replaced. Check the oil injector and oil pipelines to ensure that there is sufficient lubricating oil in the cylinder. 2. The gap between the piston rings and the grooves on the piston is too large (including radial and axial gaps); proper matching should be ensured during assembly. 3. The clearance at the opening where the piston rings are inserted into the cylinder is too small, resulting in jamming due to thermal expansion. When installing piston rings in a compressor, the clearance at this opening must be checked in accordance with technical specifications. 4. If the compressor’s piston rings have been in use for a long time, they may be severely worn out, and it is necessary to replace them with new ones

Check whether the first-stage piston is abutting against the cylinder; this can be seen by removing the first-stage cylinder head. The noises coming from the crankcase originate from the cylinders.

Abnormal noises from moving parts can be caused by the following: broken valve plates or springs, cracked or loose valve body sleeves, too small a clearance volume in the cylinder, liquid accumulation inside the cylinder, foreign objects in the cylinder, loose or broken cylinder liners, severe wear of the piston or piston rings, loose piston mounting nuts or broken piston rods, loose or broken connecting rod bolts, bearing caps bolts, and crosshead nuts, excessive clearance in the main bearings, connecting rod end bearings, and crosshead slides, loose or broken bolts for the crosshead slides, broken crosshead slides, insufficient or no tension in the bearings, and a loose fit between the crankshaft and the coupling

If everything checks out as per what the original poster checked, and there is still noise when turning the crankshaft, check whether the cylinder liner is moving

Isn’t the first dead center also the second dead center? Is the first stage vertical or horizontal? First, identify the source of the sound, then check them one by one. Your voice doesn’t seem to be coming from the crankcase. It should be inside the cylinder block; check the clearance between the cylinder and the piston ring and support ring.

Even after removing the first and second pistons along with their piston rods, there is still abnormal noise; it’s not caused by this reason. We will continue to disassemble further.

Even after removing the first and second linkage rods, there is still a ‘dada’ noise. Now I have to remove the crankshaft as well to see if there are any abnormalities; it’s really difficult to spot them just by looking at it!

The next step is to remove the crosshead; take it off along with the connecting rod. If it makes noise again after turning the shaft once more, it’s due to the main shaft

We have just encountered this issue: there is carbon deposition on the upper part of the first cylinder. Our solution is to remove the cylinder head, clean it, and readjust the clearance between the top and bottom dead centers to meet the requirements. This post was last edited by GUANGWEI8.26 on 2009-4-17 at 17:19.]

Check other places, such as the pulleys, etc.

The technician is truly skilled; upon inspection, it was indeed a loose pulley belt that caused the problem. For such an apparent issue, we disassembled everything again, learning from the experience and gaining valuable insights. Thank you thank you thank you

Uh, pulley? The belt on the cooling fan? Where is there a belt for the crankshaft of a reciprocating compressor? . . . . . . . . . . . . . . . . .

Is that a reciprocating compressor? If so, it shouldn’t be driven by a belt, right?

This old-style L-type reciprocating compressor is driven by belts; it usually has 6 belts