How to determine centrifugal pump issues by listening to sounds on-site?

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Overview of Huatianmou TPM Equipment Management Experts: In the actual conditions of chemical production, due to the harsh working environment and high levels of stress, centrifugal pumps experience relatively large vibrations. As a result, various problems and failures can occur; therefore, it is necessary to be aware of the faults that can arise in centrifugal pumps, their causes, as well as some methods for dealing with them. I. Cavitation noise: This is the sound produced when a water pump experiences cavitation, usually manifesting as a popping or cracking sound. II. Loose noise: This is the sound produced by the loosening of rotor components on the shaft. Such sounds are often periodic. If the impeller or shaft sleeve of the circulating water pump is loose on the shaft (with a clearance of even 1–3 millimeters), it will produce a knocking sound. If the pump shaft is bent at this time, the collision noise will be louder, as the impeller and shaft sleeve tend to hang downward on the shaft, resulting in a gap forming below the shaft. But when the convex surface at the bend turns upward, it impacts the impeller, causing it to move upward; before the impeller has finished moving upward, the convex surface of the pump shaft turns downward again, pushing the impeller to move downward. Thereafter, the convex surface of the pump shaft turns upward again, striking the impeller and causing it to move upward, thus producing a periodic sound. It must be pointed out that water pumps operating under such conditions are very dangerous; aside from air leaking into the pump due to the swinging of the rotor components, more serious issues can arise such as cracks in the impeller and fractures in the pump shaft (at the edges of the mating surfaces). In some rolling bearing spacers, due to not being pressed against the bearing, intermittent knocking sounds against the shaft can be heard during operation. Due to the large gap between the spacing sleeve and the shaft, when it is not pressed axially, this gap will appear below the shaft. But accidental factors can also cause the gap to move upward; due to its own weight, the spacing sleeve falls downward, producing a slight knocking sound against the shaft. III. Abnormal noises at low flow rates mainly occur in volute pumps. The noise at low flow rates is similar to cavitation noise, but in some cases it is louder, as if stones were hitting the pump casing. This is mainly a design issue related to the position of the pump tongue. IV. Abnormal noises in rolling bearings 1. In newly installed rolling bearings, excessive radial tension during assembly can make it difficult for the rolling elements to rotate, resulting in a low-level humming sound. At this point, the bearing temperature will rise. 2. If the oil level in the bearing housing is insufficient, the rolling bearings will emit a steady whistling sound during operation. 3. When the gap between the rolling elements and the spacer is too large, a loud swishing sound can be heard during operation. 4. When peeling occurs on the raceway surfaces of the inner and outer rings or on the surface of the rolling elements in a rolling bearing, intermittent shocks and vibrations will occur during operation. 5. If the rolling bearing is damaged (including a broken separator, cracked rolling elements, or cracked inner and outer rings), there will be cracking noises during operation.