The pump is noisy, with a screeching sound
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This post was last edited by Beijing Kid on 2015-6-2 at 15:43. Single-stage centrifugal pumps with single-face mechanical seals were used in two units under the same operating conditions, running 24 hours a day for about half a month; one of the pumps developed loud noise along with a screeching sound, while the other pump operated normally. That unit made noise, but its vibration levels were normal, as were its flow rate and head; it was ruled out that there was damage to the elastic elements at the coupling end or that the pipelines were blocked. Contact the manufacturer. The analysis indicates that there is a problem with the bearings of the pump or motor. The pump and motor have now been separated, and the motor is being started separately to check if there is any noise; this process is currently in progress. I would like to ask fellow sailors: what causes high noise in pumps?
High noise accompanied by screeching may be due to a bearing problem; also, check whether there is any friction in other parts of the pump. There may also be problems with the inlet and outlet valves; it is necessary to determine the source of the sound on-site.
The screaming sound should be the result of friction between metals; there are two aspects involved: 1. the impeller mouth ring； 2. Bearings.
What kind of sound do you mean by screams? And then, where is it?
This post was last edited by eidl*ang on 2015-6-2 at 18:26. 1. Examine carefully; it should be possible to determine the exact location from where the noise is coming, but one must be cautious when making a judgment. There are many ways to detect and determine it; walking over and touching it with your hand is the most straightforward method. 2. If it’s a mouthpiece issue, the outlet pressure will change ； 3. There are no other accessible parts, so it can be determined that it is a bearing issue. Based on your description, since there is no temperature rise in the bearing and the vibration levels are within normal limits, it indicates that no damage has occurred at the areas where the rolling elements make contact ； It can be preliminarily concluded that there is an issue with the assembly of the inner and outer rings of the bearing.
It might be the sound of friction between the impeller and the pump casing; adjust the distance between the impeller and the fixed pump casing by adding a PTFE ring, or adjust the distance between the impeller and the movable pump casing and also add a PTFE ring.
The bearing might be damaged, or it could be that the impeller is loose
One is the impeller and the mouth ring, and the other is the impeller and the pump casing; they can be disassembled for inspection.
Personally, I think it’s still the noise coming from the bearings. Our factory already had two pumps, and during summer the noise from their bearings was very sharp; after the bearings were replaced, the noise decreased, but it became sharp again after a short while. However, all other parameters were normal, so we didn’t pay much attention to it.
Regarding the sealing issue, several of our pumps developed this problem after having new serial seals from another manufacturer installed. Upon disassembly for inspection, no obvious areas of friction were found; yet the problem persisted even after the seals were reinstalled. The pumps continued to operate until new seals were used, after which the issue disappeared. The root cause was never identified, and when we asked the manufacturer’s after-sales technical staff, they were also unable to figure it out