Progressive Cavity Pump Disadvantages
What are Progressive Cavity Pumps?
Progressive Cavity Pumps, also known as PC pumps, are a type of positive displacement pump that uses a single helical screw within a shaped stator to transport fluids. They are commonly used in various industries for pumping viscous and shear-sensitive materials, including liquids containing soft solids.
Problems with PC pumps
However, for many applications, there are several disadvantages associated with progressive cavity pumps:
- Maintenance and Repair Complexity: PC pumps have a high number of consumable parts, including the rotor, stator, coupling, drive shaft, and mechanical seal. This complexity makes maintenance and repair more challenging.
- High Cost: Progressive cavity pumps typically have a higher initial cost compared to other pump types. Additionally, replacement parts are expensive, and the fitting time can result in extended periods of plant downtime.
- Inefficiency with Abrasive Fluids: These pumps are not suitable for abrasive fluids as the precision edges and gaps in the rotor and stator wear quickly, leading to reduced performance.
- Low Viscosity Inefficiency: PC pumps may be less efficient with low-viscosity fluids as they tend to slip past the rotor-stator fits.
- Large Footprint: PC pumps have a large footprint due to the significant number of moving parts and the length needed to produce the required pressure and flow.
- Stator Replacement: Stators may need frequent replacement, especially when exposed to abrasive fluids, causing increased maintenance costs.
- Dry Running Damage: Running a PC pump dry can quickly damage the stator and rotor, making it necessary to ensure the fluid reaches the rotor and stator without delays.
- Complex Pump Selection: Selecting the right PC pump for specific applications can be a complex process, compared to peristaltic and centrifugal pumps.
- Limited Production Rates: PC pumps have limitations on production rates and lift capacity, making them less suitable for some high-demand applications.
- Temperature Sensitivity: The stator elastomer can swell or deteriorate when exposed to certain fluids and temperatures, limiting the pump's application range.
- Vibration Issues: Constant pump vibration can lead to shaft seal failures, and high-speed applications may experience vibration problems.
- Lack of System Experience: Due to their complexity, specialist experience with system design, installation, and operation of PC pumps is needed.
- Fluid Film Requirement: PC pumps rely on a fluid film to keep sliding surfaces lubricated, and running them dry – even for less than a minute - is a common cause of failure.
- Limited Flow and Distance: PC pumps have low flow rates and can only pump limited distances. Additional equipment like VFDs and gear reducers may be needed to address this limitation.
- Volumetric Efficiency Concerns: Viscous fluids may not flow quickly enough into the pump, affecting the pump's volumetric efficiency and creating air pockets in the fluid delivery.
- High Startup Torques: PC pumps may require larger motors due to high startup torques, even if running horsepower is lower.
- Compatibility with Replacement Parts: Sourcing replacement parts from alternative suppliers can be challenging due to slight dimensional differences between manufacturers. PC pumps rely on precision fitting between rotor and stator.
In summary, while Progressive Cavity Pumps offer advantages for specific applications, they come with various limitations and challenges, making them less suitable for certain pumping needs. Users need to carefully consider these disadvantages before selecting PC pumps for their operations.
Progressive Cavity Pump Alternatives
If PC pumps don’t suit your application, we suggest looking into alternatives such as the LSM industrial hose pumps which use the peristaltic principle. Centrifugal pumps built specially for handling abrasive slurries can also be a good option.
Our pump system engineers and technical team at Atlantic Pumps can give straightforward advice on your specific pumping needs, they can be contacted by phone, WhatsApp or online.
Phone: 0800 118 2500 WhatsApp: 07537 149 180