What Is a Progressive Cavity Pump? How It Works and Where It Is Used

A progressive cavity pump moves fluid with a single helical metal screw, called the rotor, turning inside a rubber or elastomer-lined housing, called the stator. It is one of the most useful pumps for thick, abrasive or solids-laden liquids, and it is widely used in wastewater, chemical and process plants.

How a progressive cavity pump works

The rotor is shaped like a corkscrew and the stator has one more lobe than the rotor. As the rotor turns, sealed cavities form between the two and move steadily from the suction side to the discharge side. The fluid is carried along inside these cavities, which is where the name comes from.

Because every cavity holds the same volume, the flow is almost proportional to the pump speed. The flow is smooth, with very little pulsation, and the fluid is handled gently with low shear.

Where progressive cavity pumps are used

• Sludge and thickened wastewater at treatment plants.
• Polymer and chemical feed, including viscous chemicals.
• Slurries, pastes and fluids with fibres or soft solids.
• Process fluids in chemical, petrochemical and food plants.
• Loading and unloading of viscous products.

Advantages

• Handles a very wide range of viscosities, from thin liquids to pastes.
• Steady, low-pulsation flow that is easy to control with a variable speed drive.
• Gentle on shear-sensitive fluids.
• Self-priming, and able to handle fluids with solids.
• Reversible, so it can be used for loading and unloading.

Limitations to plan for

• No dry running. Without fluid the stator overheats and can be damaged within seconds, so fit dry-run protection.
• Wear parts. The rotor and stator wear over time, faster with abrasive fluids.
• Temperature and chemical limits. The stator elastomer must suit the fluid and temperature.
• Size. The pump is long compared with some other designs.

What to check before you choose one

1. Fluid, viscosity, solids content and how abrasive it is.
2. Temperature, and the right stator elastomer such as NBR, EPDM or FKM.
3. Required flow and discharge pressure. Higher pressure needs more stages.
4. Shaft sealing: packing or mechanical seal.
5. Dry-run protection and a plan for spare rotors and stators.

See also our comparison of progressive cavity and AODD pumps and our progressive cavity pumps page.

Power Energy Gulf supplies progressive cavity pumps for industrial plants in Saudi Arabia and the GCC. Contact us with your fluid, flow and pressure details and we will recommend a suitable pump.