Seeking advice on backflow issues with shielded pumps
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What is the purpose of the pipe that connects the outlet at the tail end of the shielded pump? Is this flow from the tail end to the outlet? If so, how does it flow past with such high outlet pressure?
The flow back to the tail is intended to balance the axial thrust of the impeller and to prevent a disruption in the flow of material, which could lead to poor bearing lubrication. As for how this flow takes place, you can imagine that the pressure is lowest near the center of the impeller; this allows the liquid at the pump outlet to gain head, resulting in the highest pressure there. It’s then obvious that the pressure along the return line gradually decreases. Near the center of the impeller, the pressure drops to its lowest level, creating a pressure difference across the return line, and it is this pressure difference that drives the flow of liquid.
It balances the axial force and also serves a cooling function
Exported to the end section; its main function is to lubricate bearings and cool motors
A cycle is formed by the pressure difference between the outlet and inlet, which cools the shielding sleeve, lubricates the bearings, and increases the pressure in high-temperature areas (to prevent vaporization)