Pump outlet return line
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I would like to ask fellow sailors: which pumps require the installation of an outlet return pipeline? Which ones are unnecessary?
According to specification HG20559: In front of the outlet isolation valve of each positive-displacement pump and vortex pump, a return pipe leading back to the pump inlet or suction vessel should be installed, along with a globe valve for regulating flow and testing the pump after maintenance. However, to achieve accurate flow regulation, the globe valve should be replaced with a control valve. This pipeline may not be required for metering pumps with low flow rates. Among them, diaphragm pumps belong to positive displacement pumps, while chemical pumps need to be distinguished as either positive displacement pumps or vortex pumps.
If production requires adjusting the flow rate in response to changes in operating conditions, an outlet return line must be added at the pump outlet, which is known as \"bypass control\". If a centrifugal pump might operate at a flow rate below its allowable minimum, a return line should be provided to allow a portion of the fluid to flow back from the pump’s discharge port to the container at the pump’s inlet.
That’s right; pumps that are afraid of pressure buildup all need a return line.
Positive displacement pumps require a bypass to regulate flow.