An Overview of Progressive Cavity Pumps

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  An Overview of Progressive Cavity Pumps

  Progressing cavity pumps, also known as cavity pumps or PC pumps, are a type of positive displacement pump that is commonly used for the transfer of thick, viscous liquids in various industrial applications. In this article, we will provide an overview of progressive cavity pumps, their operating principles, common types, applications and advantages over alternative pumping solutions.

  Progressive Cavity Pump Operating Principles

  Progressive cavity pumps operate based on the principles of producing a progressing cavity between a helical rotor (screw) and a matching helical inner stator (housing). As the rotor turns, it creates sealed cavities that progress along the length of the rotor. This causes the fluid to be displaced progressively from the inlet to the outlet of the pump.

  The key components are:

  • Helical rotor - A single helix rotor fitted eccentrically inside the stator. It is normally driven by a shaft connected to an external prime mover such as an electric motor.
  • Helical stator - A matching helical inner surface that forms sealed cavities with the rotor. It is stationary and serves as the pump casing.
  • Inlet - Where the fluid enters the first cavity formed between the rotor and stator.
  • Outlet - Where the fluid exits from the last cavity as it is pumped along the length of the rotor.

   

  As the rotor turns, it progresses the cavities continuously from the inlet to the outlet of the pump. This squeezing action positive displaces the fluid without relying on changes in pressure or velocity. The progressive cavity action is gentle, making it suitable for handling shear-sensitive or abrasive fluids.

  Types of Progressive Cavity Pumps

  There are different categories and sizes of progressive cavity pumps available depending on the specific application requirements:

  Standard PC Pumps

  Standard progressive cavity pumps are general-purpose models commonly used for ground level and below ground transfer applications in industries such as water and wastewater, oil and gas, petrochemical, mining, pulp and paper etc. They come in sizes ranging from 1-4" and are suitable for flow rates up to 250 m3/hr.

  Small Progressive Cavity Pumps

  Small progressive cavity pumps, also known as mini PC pumps, are compact modular models optimized for portable, truck-mounted and special low clearance applications. They typically have a maximum size of 2" and are suitable for flow rates up to 15 m3/hr.

  

  Heavy Duty PC Pumps

  Heavy duty progressive cavity pumps are larger, robust models designed to handle high viscosity fluids at elevated pressures and temperatures. They are commonly used in demanding applications in oil & gas pipelines, refineries, chemical plants etc. Their size ranges from 2-8" with flow rates up to 1000 m3/hr.

  Sanitary PC Pumps

  Sanitary progressive cavity pumps feature smooth surfaces, fewer dead-legs and crevices to facilitate cleaning-in-place (CIP) and sterilization-in-place (SIP). They are optimized for use in hygienic processes in food, dairy, beverage and pharmaceutical industries. Their material options include stainless steel and high alloy materials.

  Common Applications of Progressive Cavity Pumps

  Given their self-priming capability and ability to handle viscous or shear-sensitive fluids, progressive cavity pumps are widely used across many industries for applications such as:

  • Transfer of slurries, sludges, pastes and viscous fluids in mining, mineral processing, water/wastewater treatment, chemical plants etc.
  • Pumping of crude oil, refined products and heavy fuel oils in pipelines, tank farms and shipboard transfer in oil and gas industry.
  • Transfer of viscous emulsions, adhesives, latex, coatings and polymers in chemical, paint and petrochemical plants.
  • Pumping of biosolids, fermentation broths and juices in food and beverage processing.
  • Transfer of pulp stock and recycled fiber slurries in paper and pulp mills.
  • Dosing and transfer of fluids in pharma, cosmetic and personal care product industries.

  Advantages of Progressive Cavity Pumping

  Progressive cavity pumps offer several advantages compared to alternatives like centrifugal, lobe or peristaltic pumps when handling viscous fluids:

  • Shear-free handling - Gently squeezes fluids without damaging shear-sensitive products.
  • Self-priming capability - Can lift fluids many meters vertically without vents or foot valves.
  • Dry running capability - Can run dry for short periods without damage.
  • Robust construction - Handles abrasives and solids without risk of clogging.
  • Wide viscosity range - Pumps fluids from water-like to thick greases and pastes.
  • Sealless external drive - No mechanical seals or stuffing boxes needed.
  • No pulsing discharge - Smooth, continuous non-pulsating flow.
  • Low NPSH requirement - Suitable for high elevation installations.

  In summary, progressive cavity pumping technology is a versatile positive displacement solution well-suited for reliable handling of various thick, shear-sensitive or particulate-laden fluids across many industrial verticals.