5 Reasons to Switch from a Progressive Cavity Pump to a Rotary Lobe Pump

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5 Reasons to Switch from a Progressive Cavity Pump to a Rotary Lobe Pump

In wastewater applications, operators and engineers often have different reasons for using certain types of pump technology as it applies to various applications. One example of this is treatment plant personnel switching from a progressive cavity pump to a rotary lobe pump. Both pumps are in the positive displacement family, and while progressive cavity pumps make sense in certain application, a rotary lobe pump can be a better solution in many cases.

Reasons to switch

1. Too much downtime and difficulty repairing existing pumps. Progressive cavity pump maintenance can be a nightmare. It typically takes a mechanic four to six hours to rebuild a 20 hp PC pump. It usually must be taken offline, repaired and reinstalled. Lobe pumps are maintained inline in one to two hours. In terms of labor rates at $45 per hour, comparing PC to a lobe pump maintenance, lobe pump users on average save over $10,000 annually. Even newer progressive cavity pumps that claim to be designed for inline service are cumbersome to work on and still require significantly more time to service.

2. Parts are expensive and difficult to obtain. PC pumps typically require a stator and rotor specific to each application. In contrast, lobe pumps typically use common parts for their wet end. It’s possible to stack the lobes along the shaft while keeping the L/D ratios well within the allowable range. This drastically reduces spare parts cost and inventory requirements. Lobe pumps also deliver a wide range of flows and multiple configuration options. Using this common component philosophy, Vogelsang can provide pumps for more applications in a plant.

3. Problems with leaking. PC pumps have frequent problems with leaking at the stuffing box. The soap expands the stuffing and eventually it fails. The Vogelsang cartridge mechanical seal eliminates this problem since leaks never reach the seal.

4. Run dry is a concern or it has damaged pumps. A PC pump cannot run dry without damaging the pump. This is because a stator lies on a rotor and creates friction. The longer the friction occurs, the faster the pump is destroyed. A lobe pump runs in a totally different way. There is not a tight relationship between the lobes and the housing. This allows for the pump to run dry for up to 30 minutes without damage.

5. The current pump is taking up too much space. A lobe pump provides a much smaller footprint than a PC pump. When designing a facility using a lobe pump, it is possible to build a smaller building, smaller air handling, smaller crane systems, and no seal water or drain systems. These reduced requirements typically add up to tens, if not hundreds, of thousands of dollars saved on the overall project. Typical building cost savings could pay for the lobe pumps for the project.

Have more questions about choosing a pump technology? Vogelsang can help you sort out questions of efficiency, flows, solids handling and other factors that go into your decision.

Read more about Progressing Cavity Pumps vs. Rotary Lobe Pumps on Vogelsang’s website or contact sales@vogelsangusa.com.

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