There is no doubt that centrifugal pumps are used extensively around the globe. But at the same time, this does not make these pumps immune to wear and tear or some other technical issues. In addition to other issues, one of the common issues that is faced by centrifugal pump is ‘increased amperage’. Let us discuss the reasons behind the issue of elevated amperage –

Change in the amperage owing to its size -

  • Seeing the safety concerns, the pumps was oversized during the sizing of the pump.
  • A pump of bigger size was specified, in the hope of future requirements.
  • The speed of the pump has been surged which has led to a considerable alteration in the needed amperage.
  • The pump was sized in a way that it should offer utmost operating condition. But unfortunately the pump does not even function like the way it has been made.

Change in the amperage owing to the product variation -

  • The liquid’s viscosity surged with the alteration in the temperature. There are viscosities which rise with a reduced temperature and at times with the surged temperature.
  • With agitation, the viscosity of liquid gets increased.
  • Actually, the motor was sized and it was for the low specific gravity. However, the lines gets tested with water.
  • Due to some reason, the specific gravity of the fluid has increased considerably.

There was a friction between two parts and it was due to the displacement of the shaft. Let us discuss the reasons behind this –

  • Thermal growth.
  • Water hammer.
  • Varied forms of vibration which comprise of slipstick, harmonic, induced etc.
  • Pulley driven pumps.
  • The rotating assembly is not being dynamically balanced.
  • When the pump is functioning away from
  • Strain in the pipe.
  • A bent shaft.
  • Cavitation.
  • Misalignment between the driver and the pump.

As and when the shaft displaces, varied parts can come in contact -

  • The impeller may come in contact with the back plate and pump volute. This particular situation can happen because of the thermal growth or when there is an incorrect tuning of the impeller.
  • Some fitting or a gasket is projecting out into the stuffing box that usually comes in contact with the mechanical seal.
  • The stagnant seal face and the revolving shaft.
  • The interior part of the stuffing box and the external diameter of the mechanical seal.
  • As per the experts, the closed impeller wear rings are the key reason behind the emergence of rubbing.

Miscellaneous reasons -

  • The shaft might not be functioning in the right direction.
  • The stuffing box packing has tightened extra hard.
  • It is the mechanical seal, which is unbalanced, used in the high pressure application. The face load is on the higher side.
  • The impeller has been installed wrongly.