The service star

The progressive cavity pumps of the CC series from Vogelsang. Easier, quicker, more efficient

Following its successful implementation in the agricultural sector, it was the many positive characteristics and advantages of the rotary lobe pump that caused the “Vogelsang pump” to be discovered by new users in other areas, such as wastewater technology, industry and biogas technology. 

Developments in the German biogas sector resulted in ever-more viscous and therefore challenging and problematic suspensions in the digesters. Due to the addition of high dry matter content and fibrous solid matter, such as dung or grass silage, some pump types were increasingly reaching their limits – particularly as the suspensions also contain high levels of abrasive components and foreign matter. For this reason, other pumps seemed like a possible solution under certain circumstances, especially the progressive cavity pump, given that the conveying elements boast long running times in other areas. However, when they visited customers on-site, our biogas experts realized that there were no progressive cavity pumps available that were specifically adapted to the precise requirements and needs of biogas plants. Even if the conveying elements could guarantee a satisfactory operational time, users were frequently unsatisfied with the overall performance in everyday operations. So our biogas experts started thinking about developing our own progressive cavity pump. The final decision was not taken lightly. A Vogelsang progressive cavity pump would have to meet both the company’s own quality standards and the specific requirements of applications in biogas plants. The experts soon began to doubt whether a costeffective solution could be found for such a familiar and long-established concept as the progressive cavity pump. After all, since the patent was first registered in 1931, numerous companies had specialized in precisely these pumps. On the other hand, Vogelsang itself had played a major role in further developing and improving the rotary lobe pump concept with the IQ series, adding many useful details and making service and maintenance work and handling considerably easier.

So the experts began the necessary analyses as to exactly which characteristics of the progressive cavity pump convince customers to choose this pump, and which characteristics specifically put them off? Which improvements are users looking for, especially in the biogas sector? In conversations, customers would time and again draw attention to the complexity of changing parts. This took up a lot of space and time and very little had changed over the years when it came to ease of maintenance. Even newly launched product concepts inspired little enthusiasm among biogas plant operators, who saw no progress in the situation. In the autumn of 2014, these circumstances led progressive cavity pump experts to demand in print: “Progressive cavity pumps have to become easier to maintain!” Users also frequently complained about clogging in the suction housing and insufficiently sturdy cardan shafts or coupling rods for transferring the motor’s drive power to the rotor.

It didn’t take long for the specialists in the development department to realize that replacing parts would be even easier and, above all, quicker if the connection between the drive and rotor could be detached from the stator output. Thanks to the innovative construction, this connection is now easily accessible once the rotor/stator unit is swung out. In addition to standard mechanical engineering solutions, such as a multi-tooth or feather key connection, it soon occurred to the engineers to look into a friction-locked cone joint. They were familiar with the concept from other projects, where it had proven useful. The key advantage is that the drive shaft and the rotor do not need to be positioned precisely to one another. In addition, the connection is self-centering, thanks to the taper. It can simply be tensioned or released using a threaded rod via the through bore in the rotor. With this connection, there is no need for laborious removal of small pins in a tight suction housing or other complicated tasks.

The developers’ painstaking work and perseverance with the development was amply rewarded. The new pump proved itself superlatively in tests on its dedicated test bench and in the field. In May 2014, the patent was registered. That same year, the new design from Vogelsang won over the jury of an innovation competition. As part of EnergyDecentral 2014, the unique concept of the CC series was awarded the silver medal. 

The market had a far more important reward in store: The new concept inspired strong interest from customers, especially in the biogas sector, for which it had been developed. Established competitors on the market soon followed with similar concepts. However, thanks to its patent protection, the original from Vogelsang remains unsurpassed. And to ensure that it stays that way, the CC series is being constantly developed further, as you would expect from Vogelsang. Today, Vogelsang offers single-stage and two-stage geometries in four series with volume flows of up to 300 m³/h.