What causes the high temperature of the pump body in a shielded pump? ?
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This post was last edited by lovestory on 2011-1-6 22:37. I recently encountered a difficult problem! The temperature of the casing of the horizontal shielded pump reached 71 degrees; the temperature at the pump inlet was 37 degrees, while it was 39 degrees at the pump outlet. The balance pipe was unobstructed and its temperature was also 39 degrees. The vibration level was 1.5 MM/S, and the readings from the bearing monitor TRG were normal as well! Could everyone please help discuss why the pump body temperature is so high? What caused it? :sleepy:
May I ask, for the pump body temperature of 71°C you mentioned, which part of the pump body does this refer to? Has it always been this temperature? Has it increased recently? If the temperature remains constant, I believe it is considered normal. With the temperature of the working medium approaching 40°C, plus the temperature rise due to the motor itself, the temperature of the pump body reaches 71°C. If the temperature has risen recently, it might be because there is some blockage in the circulation within the motor cavity, resulting in less heat being carried away by the circulating fluid and thus an increase in temperature ； Or the valve on the outlet pipe has been opened more widely recently than before, resulting in a higher load and increased heat generation in the motor
Check whether the tail pipe is unobstructed, and check if there is air trapped inside the pump
Does the pump body have a cooling water jacket? Check if the cooling water pipes are unobstructed
Description: This pump has no water jacket； The temperature at the middle part of the pump body is 71 degrees; it has recently risen to this level, as it was previously 65 degrees ； Adjustment: Lower the temperature of the inlet medium and the exhaust gas. Result: The temperature remains at 71 degrees. Question: Why is the temperature difference between the inlet and outlet only about 2 degrees? And what about the high temperature in the middle part of the pump body?
This post was last edited by ygxxgy on 2011-1-7 at 13:05. Based on your description, here is further inference: 1. The temperature in the middle section of the pump used to be 65 degrees, but it has recently risen to 75 degrees. I suspect that the gap designed between the rotor and stator shields might be too small, resulting in insufficient circulation of fluid; this prevents the maximum amount of heat from being removed from the middle section of the pump, hence the higher temperature there； Or perhaps two shielded compartments are partially blocked by debris ； (The temperature of the canned pumps I’ve used is generally around 30-40 degrees.) 2. There’s no issue with the gap in the casing; this phenomenon is caused by excessive heat generation in the stator. If the load is within the design limit, you can ask the electrician. Additionally, does the standby pump have such issues under the same process conditions and load? If so, the possibility of a problem with the pump is higher ； If not, it is necessary to contact the manufacturer’s staff to come and disassemble the pump for a thorough inspection.
The standby pump does not have this problem, as it is a device that was upgraded this year (installed recently) and has good performance! There is no such problem
It’s probably because the tail pipe isn’t very clear. Another issue is that the rotor might bulge.
One thing that needs to be clear from the start is that when transporting ordinary media, it is normal for the temperature of the motor section to be within 60 degrees higher than the temperature of the material at the inlet; however, it is preferable for this difference to be within 30 degrees. When trying to determine the cause of a problem, one should not rely solely on the readings provided by bearing monitoring devices such as TRG meters. Instead, it is necessary to carefully listen using a vibration detector to the vibrations of the front and rear bearings as well as the sound of the material flowing inside, and to check whether there is any gasification occurring. A comprehensive assessment is required. Excessively high motor temperatures are not necessarily caused by problems with the pump itself; partial gasification of the medium or temporary local vacuum conditions can also be responsible. Additionally, if there is a spare pump, after shutting down the pump that is no longer in use, disassemble it and check its bearings; handling the materials plus the inspection will take about an hour
I just read the original poster’s reply; it’s a pump made by Nippon Kikai. It’s just average – its bearings are one tier below those of German-made pumps. Don’t place too much trust in Japanese products!
If it’s not a blockage as the original poster said, it’s likely that the load has increased recently, causing the motor to generate more heat; you can slightly reduce the valve opening on the outlet pipe!