What issues should be considered when using shielded pumps for loading and unloading?
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Our company used pipeline pumps for loading and unloading goods. Since some of the raw materials handled contained butane components that are prone to vaporization, the seals of these pipeline pumps failed frequently, resulting in severe leaks, which greatly affected operational efficiency and safety. The company is now considering replacing the pump, intending to use a canned motor pump instead of a pipeline pump for loading and unloading. Since shielded pumps cannot operate under vacuum conditions, it is possible for a vacuum to occur toward the end of the unloading process. So, can such shielded pumps be used for unloading? Loading isn’t a problem; it’s the unloading that’s concerning. Who knows when it will be done? And that anti-rotation device either isn’t very reliable either, right? Do fellow sailors have any ways to solve this, or are there centrifugal pumps that aren’t afraid of being taken out of service?
The bearings of shielded pumps are lubricated by the fluid itself; once the pump is evacuated, the consequences can be severe. Centrifugal pumps can be equipped with double-end seals along with P72+76 to address seal leakage issues
The advantage of a shielded pump is that it has no external seal, preventing the medium from leaking out. However, its structural characteristics require a medium to cool the motor and bearings; once the volume of this medium is reduced, it can lead, in mild cases, to a disruption of axial balance and thus damage to the thrust bearings, while in severe cases it can cause the shaft or motor coils to burn out. Therefore, solutions must be found at the process level – perhaps by utilizing low liquid level alarms or interlocks that shut down the pump when the liquid level drops too low Shut down the pump when current drops suddenly?
1. Inlet filter screen: the fine-mesh screen cannot be removed; graphite bearings are most sensitive to dirt and running out of air. 2. When disassembling and assembling, pay attention to the serial number, the gap of the graphite bushing, and the G value of the impeller.