How to design the inlet and outlet pipelines of centrifugal water pumps

1.Piping requirements for suction and discharge pipes of centrifugal water pumps

1) All pipelines connected to the pump (pipe burst test) shall have independent and firm supports to reduce the vibration of the pipeline and prevent the weight of the pipeline from being pressed on the pump.
2) Adjustable brackets should be provided at the pump inlet and outlet pipes. Vibration-reducing pipes should be provided with damping brackets to properly adjust the position of the pipes to reduce the additional force on the pump nozzle due to installation errors.
3) When the pipeline connecting the pump and the equipment is short and the two are not on the same foundation, the connecting pipeline should be flexible, or metal hoses should be added to compensate for uneven settlement of the foundation.
4) The diameter of the suction and discharge lines should not be smaller than the diameter of the inlet and outlet of the pump.
5) The suction pipe of the pump should meet the net positive suction head (NPSH) required by the pump, and the pipe should be as short as possible with few turns. When the pipe length exceeds the distance between the equipment and the pump, the process system should be checked.
6) In order to prevent cavitation of the pump, the elevation of the inlet nozzle pipe from the equipment to the pump should be gradually lowered, and there should be no U-shape in the middle! When it is unavoidable, add a vent valve at a high point and a drain valve at a low point.
7) The length of the straight pipe section before the inlet of the centrifugal pump should not be less than 3D of the inlet diameter.
8) For dual suction pumps, to avoid cavitation of the centrifugal pump caused by uneven bidirectional suction, the double suction pipes should be arranged symmetrically to ensure uniform flow distribution on both sides.
9) The piping arrangement of the pump end and drive end of the reciprocating pump should not hinder the disassembly and maintenance of the piston and tie rod.


2.Auxiliary pipeline setting of centrifugal water pump

1) Warm pump pipeline: When the temperature of the centrifugal pump conveying material exceeds 200 ℃, a warm pump pipeline needs to be set up, so that a small amount of material is led from the discharge pipe of the operating pump to the backup pump outlet, and then flows through the backup pump and back to the pump inlet to make the backup The pump is in a hot standby state for easy startup.
2) Anti-condensation pipeline: For pumps with condensable medium at room temperature, anti-freezing pipes of DN20 25 should be provided, and the setting method is the same as that of warm pump pipelines.
3) Balanced pipeline: When the medium is likely to vaporize at the pump inlet, a balance tube that can return to the gas phase space of the upstream equipment on the suction side can be set between the pump inlet nozzle and the pump inlet shutoff valve to return the generated gas. To avoid cavitation of the pump, a shut-off valve should be provided on the balance pipe.
4) Minimum return pipe: In order to prevent the centrifugal pump from operating below the minimum flow rate of the pump, a minimum return pipe of the pump should be set up to return a part of the fluid from the pump discharge port to the container at the pump suction end to ensure the pump flow rate.


Because of the special characteristics of the centrifugal pump, the pump performance and the process materials running in the pump need to be fully understood, and the inlet and outlet pipelines must be reasonably configured to ensure its safe and stable operation.

2020-04-01T15:18:22+08:00April 1st, 2020|