Maintenance Chemical Pump Maintenance

Author / Editor: Xavier Rasotto / Wolfgang Ernhofer

Transfer pumps form a key part of any chemical plant. These pumps must operate reliably, often around the clock and handling a variety of corrosive or otherwise difficult materials. This article explains how to plan and carry out routine maintenance of centrifugal chemical pumps so as to avoid pump downtime and consequent lost production.

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The oil level must be at the halfway point in the sight glass. (Picture: Griswold)
The oil level must be at the halfway point in the sight glass. (Picture: Griswold)

For decades, the commonest form of pump used in chemical-processing facilities has been the centrifugal pump. These versatile machines use a rotating impeller, propeller or rotor to impart kinetic energy to the fluid being pumped. As the fluid leaving the impeller is slowed by the stationary parts of the pump, this kinetic energy is then converted into pressure energy [1].

Centrifugal pumps are versatile, with the ability to handle a variety of challenges and potential problems, including:

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  • changes in ambient temperature and humidity
  • line shock from piping that is not properly anchored
  • piping with sharp bends instead of the preferred gentle curves
  • changes in the viscosity and other characteristics of the liquid being pumped
  • large and periodic changes in hydraulic operating point

The two most common styles of centrifugal pumps are:

  • End-Suction: Ideal for thin liquids and the top choice for most water-pumping applications.
  • Self-Priming: This type has the ability to lift fluid, which gives it an advantage when the source is below the centerline of the pump.

Both of these pump types, and others, are available in ANSI format, which describes centrifugal pumps meeting the manufacturing criteria established by the American National Standards Institute in 1977 [2].

Robust as they are, centrifugal pumps will only perform at their best if operators provide the right kind of preventive and protective maintenance. This article will demonstrate how a strict maintenance routine can keep centrifugal pumps running reliably and economically in the harsh environment of a chemical plant.