Under what circumstances is it necessary to install a return pipe at the pump outlet?
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Under what circumstances is it necessary to install a return pipe at the pump outlet? What requirements must be met for the installation of the return pipe?
When the pump is over-sized, resulting in excessive flow rate or high outlet pressure, a return pipe is installed; there are no specific requirements, as long as the minimum flow rate required for production and the operation of the pump is met.
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1. It’s difficult to choose pumps that are too small, especially those with a high outlet pressure; as a solution, it is necessary to add a minimum return line. 2. In cases where the actual operating conditions may deviate significantly from the design conditions (i.e., when the load may be much lower than the designed value), it is necessary to consider adding a minimum return line.
For heat exchangers with media at relatively high temperatures, circulation water pumps need to be designed in such a way that when fine adjustments are made at low load levels, not much circulation water is required. However, if no water flows, scaling of the heat exchanger may occur; to prevent this, a return pipeline is installed from the pump outlet to the inlet to increase the flow rate and thus avoid scaling
Add a return pipe due to the frequent changes in actual operating conditions
To ensure stable pressure control at different flow rates for exports, a return pipeline and a control valve assembly are necessary. The problem is that in China, motors and pumps are often selected in a way that results in overpowered systems (especially for shielded pumps operating at low flow rates); this leads to high return flows, which cause the material temperature to rise, and ultimately result in cavitation. Therefore, it is important to choose the right motor and pump; otherwise, even if you install a return pipeline, you won’t achieve good long-term performance.
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Where should the return pipe be connected? Is it in front of the pump’s outlet valve or behind it?
Where are reflux lines usually installed?