Introduction to Centrifugal Pumps

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Following drawing shows an electric motor-driven horizontal pump that is familiar to plant layout designers.

  1. The two primary piping connections are the suction and discharge nozzles (i.e., liquid inlet and outlet).
  2. The impeller within the pump case draws the liquid into the pump and sends it out at a high velocity.
  3. The impeller shaft is sealed with a stuffing box where the shaft exits the case to prevent the pump fluid from leaking.
  4. Drips from wearing seals are picked up in the stuffing box drain.
  5. The pump shaft is connected to the drive shaft by at coupling, which is enclosed within protective housing.
  6. Both pump and driver are mounted on a common base plate.
  7. Miscellaneous pump leaks that collect within the baseplate during operation are drained through a connection at the front of the pump.

Pump size and configuration vary for the following reasons:

  1. The commodity being pumped.
  2. The viscosity of the liquid.
  3. Capacity.
  4. Pressure.
  5. Temperature.
  6. Available head requirements.
  7. Physical limitations.

Initial pump piping layouts are done with preliminary information. The equipment engineer supplies the plant layout designer with a catalog cut of the pump that most closely represents the one to be purchased.

In many cases, this data does not change significantly if the engineer has made the correct selection. Piping layouts are started early in the study phase; when the certified vendor drawings become available later in the project, minor adjustments are made as
required.

Dimensions of nozzle locations or base-plate sizes may change slightly, but revisions to physical nozzle locations (i.e., from top to side or side to front) do not usually occur when the data is finalized.

Working closely with the equipment and system engineers acquaints the principal parties with the exact design conditions and minimizes rework.

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