Feb 01

What is the difference in operation between positive displacement pump and centrifugal pump?

Positive Displacement Pumpswill not p roduce the same flow at a given speed (RPM) no matter the discharge pressure.

positive displacement pump

positive displacement pump

Positive Displacement Pump must not be operated against a closed valve on the discharge side of the pump because it has no shut-off head like Centrifugal Pumps. A Positive Displacement Pump operating against a closed discharge valve, will continue to produce flow until the pressure in the discharge line are increased until the line bursts or the pump is severely damaged – or both.

The positive displacement pump can be applied as

  • rotary lobe pump
  • progressing cavity pump
  • rotary gear pump
  • piston pump
  • diaphragm pump
  • screw pump

When positive displacement pumps serve as a screw pump for feeding drilling fluids decanter centrifuge, when you change the frequency of the main motor through the VFD control panel, the treating capacity of decanter centrifuge will change, so the flow rate need to be lessed.

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Apr 15

When to use a centrifugal or a Positive Displacement pump (“PD Pump”) is not always a clear choice. Usually we use a positive displacement pump to feed for decanter centrifuge, it is called single screw pump.

The major benefit to use a positive displacement pump other than centrifugal pumpis that, it will not break the fine solids to smaller, so the centrifuge can separate the solids easily. Centrifugal force of centrifugal pump will cut the solids to smaller, it is not good for centrifuge’s operation.

positive displacement pump for centrifuge

positive displacement pump for centrifuge

How to operate a screw pump when feeding to decanter centrifuge?

1 Full fill the pump chamber with drilling fluids , if the media is too viscosity, then inject into other liquids; Inject the mud from the pump inlet connection, and rotate the pump by hand along the running direction of the motor to make the mud full fill the suction chamber.

2 Open the screw pump inlet valve and outlet valve (the valve is fully opened to prevent overload or no load suction), start the motor.

3 The pump should be started under the condition of fully opening the Inhale row valve and bypass valve to minimize the start load. Gradually close the bypass valve after the motor reaching the rated revolution.

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written by GN solids Control \\ tags: , , , ,